Method and apparatus for providing always-on attribute of PDU session and for providing interworking aspect with respect to always-on PDU session

Abstract

To provide a method, an apparatus and a computer program product for enabling network determination of whether a PDU session will be an always-on PDU session.SOLUTION: A method may include: receiving, from UE, a PDU session establishment request message, the PDU session establishment request message comprising an always-on PDU session requested IE set to a value indicative of a request to establish a new-always on PDU session (e.g., "Always-on PDU session requested"); and, upon a determination that the requested PDU session shall be established as an always-on PDU session, transmitting a PDU session establishment accept message, the PDU session establishment accept message comprising an always-on PDU session indication IE that is set to a value indicative of always-on PDU session required ("Always-on PDU session required").SELECTED DRAWING: Figure 1B

Description

Technical Field

[0001] Exemplary embodiments generally relate to methods and apparatuses for providing an always-on connection as an attribute of a protocol data unit (PDU) session and for providing aspects of interworking with respect to an always-on connection PDU session, and more particularly, to methods and apparatuses for providing a function that enables a network to determine whether a PDU session can be made an always-on connection PDU session.

Background Art

[0002] In the fifth generation wireless system (5G), a user equipment (UE) cannot initiate a service request procedure while another service request procedure is in progress. That is, a new service request procedure can only be initiated when an old service request procedure has been completed. Due to this limitation, there may be a delay in services that use a PDU session requested to be reactivated in a new service request procedure.

[0003] Such a delay can be a problem for services that are sensitive to delay, and thus, an "always-on connection PDU session" has been introduced. An always-on connection PDU session is a PDU session that requires activation of user plane resources during the transition from the 5GMM-IDLE mode to the 5GMM-CONNECTED mode. Such a PDU session may be established based on an instruction from an upper layer. However, the current specification (i.e., 3GPP TS24.501) does not provide any instruction on how the upper layer of the UE can be configured to provide an instruction.

[0004] Therefore, network control is missing from the always-on PDU session. Specifically, the network does not recognize whether the PDU session is an always-on PDU session, and the network cannot configure the PDU session as an always-on PDU session or an on-demand PDU session. Since an always-on PDU session may consume more network resources than an on-demand PDU session, this application proposes a solution to introduce network control for the always-on PDU session.

Summary of the Invention

[0005] In the current specification, the "always-on" property is not considered an attribute of the PDU session. Examples of existing PDU session attributes are SSC mode, PDU session type, DNN, and S-NSSAI. It is necessary to maximize the commonality among these attributes. More specifically, since the UE can minimize the number of user subscription checks for determining the always-on property, it must be able to indicate to the network whether to request to make the PDU session always-on via the PDU session establishment request message. That is, when the always-on property is not required and the DNN is the Internet, the SMF can be configured to determine the PDU session as an on-demand PDU session without checking the user's subscription. However, it should not be misunderstood that the network can determine to make the PDU session always-on. The determination of always-on may only be made when requested by the UE. However, whether the PDU session can be made an always-on PDU session is determined by the network. In an always-on PDU session, it may be necessary to maintain session continuity during system interworking, so it is necessary to specify the aspect of interworking. These aspects of interworking are missing from the current specification.

[0006] To provide and / or utilize an always-on connection as an attribute of a protocol data unit (PDU) session, and to provide an interworking aspect with respect to an always-on connection PDU session, a method, an apparatus, and a computer program product are provided according to an exemplary embodiment. Further, a method, an apparatus, and a computer program product are provided for providing a function that enables a network to determine whether a PDU session can be made an always-on connection PDU session.

[0007] In some embodiments, a method for performing a service request procedure may be provided, the method comprising receiving, from a user equipment (UE), a protocol data unit (PDU) session establishment request message, the PDU session establishment request message being configured to indicate a request to establish a new PDU session, the PDU session establishment request message comprising an always-on connection PDU session requested information element (IE), the always-on connection PDU session requested IE being set to a value indicating a request to establish a new always-on connection PDU session, or the PDU session establishment request message not comprising an always-on connection PDU session requested IE, and determining, based on the local policy or configuration and the always-on connection PDU session requested IE in an available instance, whether the requested PDU session is to be established as an always-on connection PDU session.

[0008] In some embodiments, the method may further comprise causing the transmission of a PDU session establishment approval message if it is determined that the requested PDU session is to be established as an always-on connection PDU session, the PDU session establishment approval message comprising an always-on connection PDU session indication IE, the always-on connection PDU session indication IE being set to a value indicating that an always-on connection PDU session is requested.

[0009] In some embodiments, the method may further comprise causing transmission of a PDU session establishment approval message if it is determined that the requested PDU session is not established as an always-on PDU session. The PDU session establishment approval message comprises an always-on PDU session indication IE. If the UE includes the IE for the always-on PDU session request in the PDU session establishment request message, the always-on PDU session indication IE is set to a value indicating that "always-on PDU session is not permitted", or if the UE does not include the IE for the always-on PDU session request in the PDU session establishment request message, the always-on PDU session indication IE is not included.

[0010] In some embodiments, in an instance where the always-on PDU session indication IE is included in the PDU session establishment approval message and the always-on PDU session indication IE is set to a value indicating that "always-on PDU session is requested", the method further comprises causing the UE to consider the established PDU session as an always-on PDU session.

[0011] In some embodiments, in an instance where the always-on PDU session indication IE is not included in the PDU session establishment approval message, or the always-on PDU session indication IE is included in the PDU session establishment approval message and the always-on PDU session indication IE is set to a value indicating that "always-on PDU session is not permitted", the method further comprises causing the UE not to consider the established PDU session as an always-on PDU session.

[0012] In some embodiments, the method may further comprise maintaining the always-on PDU session indication at the UE and the SMF during an inter-system change from the N1 mode to the S1 mode.

[0013] In some embodiments, the method may further comprise determining, based on an always-on PDU session indication, whether a PDU session transferred from an evolved packet system (EPS) is an always-on PDU session when changing between systems from the S1 mode to the N1 mode.

[0014] In some embodiments, an apparatus for performing a service request procedure may be provided, the apparatus comprising at least one processor and at least one memory including computer program code, the at least one memory and the computer program code being configured, with the processor, to receive, from a user equipment (UE), a protocol data unit (PDU) session establishment request message, the PDU session establishment request message being configured to indicate a request to establish a new PDU session, the PDU session establishment request message comprising an always-on PDU session requested information element (IE), the always-on PDU session requested IE being set to a value indicating a request to establish a new always-on PDU session, or the PDU session establishment request message not comprising an always-on PDU session requested IE, and to determine, based on the local policy or configuration and the always-on PDU session requested IE in an available instance, whether to establish the requested PDU session as an always-on PDU session.

[0015] In some embodiments, the at least one memory and the computer program code are further configured, with the processor, to cause the apparatus to transmit a PDU session establishment approval message when it is determined that the requested PDU session is to be established as an always-on PDU session, the PDU session establishment approval message comprising an always-on PDU session indication IE, the always-on PDU session indication IE being set to a value indicating that an always-on PDU session is requested.

[0016] In some embodiments, at least one memory and computer program code, together with a processor, are further configured to cause the apparatus to transmit a PDU session establishment approval message if it is determined that the requested PDU session is not established as an always-on PDU session, the PDU session establishment approval message comprising an always-on PDU session indication IE, the always-on PDU session indication IE being set to a value indicating that an always-on PDU session is not permitted if the UE included an IE for an always-on PDU session request in the PDU session establishment request message, or the always-on PDU session indication IE being absent if the UE did not include an IE for an always-on PDU session request in the PDU session establishment request message.

[0017] In some embodiments, in an instance where the always-on PDU session indication IE is included in the PDU session establishment approval message and the always-on PDU session indication IE is set to a value indicating that an always-on PDU session is requested, at least one memory and computer program code, together with a processor, are further configured to cause the apparatus to consider the established PDU session as an always-on PDU session for the UE.

[0018] In some embodiments, in an instance where the always-on PDU session indication IE is not included in the PDU session establishment approval message, or the always-on PDU session indication IE is included in the PDU session establishment approval message and the always-on PDU session indication IE is set to a value indicating that an always-on PDU session is not permitted, at least one memory and computer program code, together with a processor, are further configured to cause the apparatus to not consider the established PDU session as an always-on PDU session for the UE.

[0019] In some embodiments, at least one memory and computer program code, in combination with a processor, are further configured to cause the apparatus to cause the UE and the SMF to maintain a always-on PDU session indication when changing the system from the N1 mode to the S1 mode.

[0020] In some embodiments, at least one memory and computer program code, in combination with a processor, are further configured to cause the apparatus to determine whether a PDU session transferred from an evolved packet system (EPS) is an always-on PDU session based on the always-on PDU session indication when changing the system from the S1 mode to the N1 mode.

[0021] In some embodiments, a computer program product for performing a service request procedure may be provided, the computer program product comprising at least one non-transitory computer-readable storage medium storing computer-executable program code instructions, the computer-executable program code instructions comprising receiving, from a user equipment (UE), a protocol data unit (PDU) session establishment request message, the PDU session establishment request message being configured to indicate a request to establish a new PDU session, the PDU session establishment request message comprising an information element (IE) requested for an always-on PDU session, the IE requested for the always-on PDU session being set to a value indicating a request to establish a new always-on PDU session, or the PDU session establishment request message not comprising the IE requested for the always-on PDU session; and determining, based on the local policy and configuration and the IE requested for the always-on PDU session in an available instance, whether to establish the requested PDU session as an always-on PDU session.

[0022] In some embodiments, when the computer-executable program code instructions determine that if the requested PDU session is to be established as an always-on PDU session, the computer-executable program code instructions further include program code instructions that cause the transmission of a PDU session establishment approval message. The PDU session establishment approval message includes an always-on PDU session indication IE, and the always-on PDU session indication IE is set to a value indicating that an always-on PDU session is requested.

[0023] In some embodiments, when the computer-executable program code instructions determine that if the requested PDU session is not to be established as an always-on PDU session, the computer-executable program code instructions further include program code instructions that cause the transmission of a PDU session establishment approval message. The PDU session establishment approval message includes an always-on PDU session indication IE. When the UE includes the IE requesting an always-on PDU session in the PDU session establishment request message, the always-on PDU session indication IE is set to a value indicating that an always-on PDU session is not permitted. Or, when the UE does not include the IE requesting an always-on PDU session in the PDU session establishment request message, the always-on PDU session indication IE is not included.

[0024] In some embodiments, in an instance where the always-on PDU session indication IE is included in the PDU session establishment approval message and the always-on PDU session indication IE is set to a value indicating that an always-on PDU session is requested, the computer-executable program code instructions further include program code instructions for causing the UE to regard the established PDU session as an always-on PDU session.

[0025] In some embodiments, when the always-on PDU session indication IE is not included in the PDU session establishment approval message, or when the always-on PDU session indication IE is included in the PDU session establishment approval message and the always-on PDU session indication IE is set to a value indicating that "always-on PDU session is not permitted", the computer-executable program code instructions further comprise program code instructions for causing the UE not to regard the established PDU session as an always-on PDU session.

[0026] In some embodiments, the computer-executable program code instructions further comprise program code instructions for maintaining the always-on PDU session indication at the UE and the SMF when changing the system between the N1 mode and the S1 mode.

[0027] In some embodiments, the computer-executable program code instructions further comprise program code instructions for determining, based on the always-on PDU session indication, whether a PDU session transferred from the evolved packet system (EPS) is an always-on PDU session when changing the system from the S1 mode to the N1 mode.

[0028] In some embodiments, an apparatus for performing a service request procedure may be provided. The apparatus includes means for receiving, from a user equipment (UE), a protocol data unit (PDU) session establishment request message, the PDU session establishment request message being configured to indicate a request to establish a new PDU session, the PDU session establishment request message including an always-on PDU session requested information element (IE), the always-on PDU session requested IE being set to a value indicating a request to establish a new always-on PDU session, or the PDU session establishment request message not including the always-on PDU session requested IE; local policy or configuration; and means for determining, in an instance where the always-on PDU session requested IE is available, whether the requested PDU session is to be established as an always-on PDU session based on the always-on PDU session requested IE.

[0029] In some embodiments, if the apparatus determines that the requested PDU session is to be established as an always-on PDU session, the apparatus may further include means for triggering transmission of a PDU session establishment approval message, the PDU session establishment approval message including an always-on PDU session indication IE, the always-on PDU session indication IE being set to a value indicating that an always-on PDU session is requested.

[0030] In some embodiments, if the apparatus determines that the requested PDU session is not to be established as an always-on PDU session, the apparatus may further include means for triggering transmission of a PDU session establishment approval message, the PDU session establishment approval message including an always-on PDU session indication IE, the always-on PDU session indication IE being set to a value indicating that an always-on PDU session is not permitted if the UE includes the always-on PDU session requested IE in the PDU session, or the always-on PDU session indication IE not being included if the UE does not include the always-on PDU session requested IE in the PDU session establishment request message.

[0031] In some embodiments, in an instance where the always-on PDU session indication IE is included in the PDU session establishment approval message and the always-on PDU session indication IE is set to a value indicating that an always-on PDU session is requested, the apparatus further comprises means for causing the UE to consider the established PDU session as an always-on PDU session.

[0032] In some embodiments, in an instance where the always-on PDU session indication IE is not included in the PDU session establishment approval message, or the always-on PDU session indication IE is included in the PDU session establishment approval message and the always-on PDU session indication IE is set to a value indicating that an always-on PDU session is not permitted, the apparatus further comprises means for causing the UE not to consider the established PDU session as an always-on PDU session.

[0033] In some embodiments, the apparatus may further comprise means for maintaining the always-on PDU session indication at the UE and the SMF when changing between systems from the N1 mode to the S1 mode.

[0034] In some embodiments, when changing between systems from the S1 mode to the N1 mode, the apparatus may further comprise means for determining whether a PDU session transferred from the evolved packet system (EPS) is an always-on PDU session based on the always-on PDU session indication.

[0035] In some embodiments, causing the transmission of a Protocol Data Unit (PDU) session establishment request message, the PDU session establishment request message being configured to indicate a request to establish a new PDU session, the PDU session establishment request message comprising a connection-oriented PDU session requested information element (IE) set to a value indicating a request to establish a new connection-oriented Protocol Data Unit (PDU) session, or the PDU session establishment request message not comprising a connection-oriented PDU session requested IE, causing the transmission, and, when it is determined that the requested PDU session is to be established as a connection-oriented PDU session, receiving a PDU session establishment approval message, the PDU session establishment approval message comprising a connection-oriented PDU session indication IE, the connection-oriented PDU session indication IE being set to a value indicating that a connection-oriented PDU session is requested, receiving, and, when it is determined that the requested PDU session is not to be established as a connection-oriented PDU session, receiving a PDU session establishment approval message, the PDU session establishment approval message comprising a connection-oriented PDU session indication IE, the connection-oriented PDU session indication IE being set to a value indicating that a connection-oriented PDU session is not permitted if the UE included a connection-oriented PDU session requested IE in the PDU session establishment request message, and not comprising a connection-oriented PDU session indication IE if the UE did not include a connection-oriented PDU session requested IE in the PDU session establishment request message, may provide a method comprising.

[0036] In some embodiments, the method may further comprise, in an instance where a connection-oriented PDU session indication IE is included in the PDU session establishment approval message and the connection-oriented PDU session indication IE is set to a value indicating that a connection-oriented PDU session is requested, considering the established PDU session as a connection-oriented PDU session.

[0037] In some embodiments, the method may further comprise not treating an established PDU session as an always-on PDU session in an instance where the always-on PDU session indication IE is included in the PDU session establishment approval message and the always-on PDU session indication IE is set to a value indicating that an always-on PDU session is not permitted.

[0038] In some embodiments, an apparatus may be provided that includes at least one processor and at least one memory including computer program code, the at least one memory and the computer program code being configured, with the processor, to cause transmission of a protocol data unit (PDU) session establishment request message, the PDU session establishment request message being configured to indicate a request to establish a new PDU session, the PDU session establishment request message comprising a persistent PDU session requested information element (IE) set to a value indicating a request to establish a new persistent protocol data unit (PDU) session, or the PDU session establishment request message not comprising a persistent PDU session requested IE, to cause transmission; and, upon determining that the requested PDU session is established as a persistent PDU session, to receive a PDU session establishment approval message, the PDU session establishment approval message comprising a persistent PDU session indication IE, the persistent PDU session indication IE being set to a value indicating that a persistent PDU session is requested; and, upon determining that the requested PDU session is not established as a persistent PDU session, to receive a PDU session establishment approval message, the PDU session establishment approval message comprising a persistent PDU session indication IE, the persistent PDU session indication IE being set to a value indicating that a persistent PDU session is not permitted if the UE included the persistent PDU session requested IE in the PDU session establishment request message, or not comprising a persistent PDU session indication IE if the UE did not include the persistent PDU session requested IE in the PDU session establishment request message, at least to cause the apparatus to perform.

[0039] In some embodiments, at least one memory and computer program code, in combination with a processor, further configure the apparatus to consider an established PDU session as an always-on PDU session in an instance where an always-on PDU session indication IE is included in a PDU session establishment approval message and the always-on PDU session indication IE is set to a value indicating that an always-on PDU session is requested.

[0040] In some embodiments, at least one memory and computer program code, in combination with a processor, further configure the apparatus to not consider an established PDU session as an always-on PDU session in an instance where an always-on PDU session indication IE is included in a PDU session establishment approval message and the always-on PDU session indication IE is set to a value indicating that an always-on PDU session is not permitted.

[0041] In some embodiments, a computer program product may be provided that includes at least one non-transitory computer-readable storage medium storing computer-executable program code instructions, the computer-executable program code instructions being to cause transmission of a protocol data unit (PDU) session establishment request message, the PDU session establishment request message being configured to indicate a request to establish a new PDU session, the PDU session establishment request message including a always-on PDU session requested information element (IE) set to a value indicating a request to establish a new always-on protocol data unit (PDU) session, or the PDU session establishment request message not including a always-on PDU session requested IE, to cause transmission, to determine that if the requested PDU session is established as an always-on PDU session, to receive a PDU session establishment approval message, the PDU session establishment approval message including a always-on PDU session indication IE, the always-on PDU session indication IE being set to a value indicating that an always-on PDU session is requested, to receive, and to determine that if the requested PDU session is not established as an always-on PDU session, to receive a PDU session establishment approval message, the PDU session establishment approval message including a always-on PDU session indication IE, the always-on PDU session indication IE being set to a value indicating that an always-on PDU session is not permitted if the UE included the always-on PDU session requested IE in the PDU session establishment request message, or not including a always-on PDU session indication IE if the UE did not include the always-on PDU session requested IE in the PDU session establishment request message, and comprising program code instructions for performing the above.

[0042] In some embodiments, the computer-executable program code instructions further comprise program code instructions for treating an established PDU session as an always-on PDU session in an instance where the always-on PDU session indication IE is included in the PDU session establishment approval message and the always-on PDU session indication IE is set to a value indicating that an always-on PDU session is requested.

[0043] In some embodiments, the computer-executable program code instructions further comprise program code instructions for not treating an established PDU session as an always-on PDU session in an instance where the always-on PDU session indication IE is included in the PDU session establishment approval message and the always-on PDU session indication IE is set to a value indicating that an always-on PDU session is not permitted.

[0044] In some embodiments, a means for causing transmission of a protocol data unit (PDU) session establishment request message, the PDU session establishment request message being configured to indicate a request to establish a new PDU session, the PDU session establishment request message comprising a non - access stratum (NAS) PDU session request information element (IE) set to a value indicating a request to establish a new always - on PDU session, or the PDU session establishment request message not comprising a NAS PDU session request IE; a means for receiving a PDU session establishment approval message when it is determined that the requested PDU session is established as an always - on PDU session, the PDU session establishment approval message comprising a NAS always - on PDU session indication IE, the NAS always - on PDU session indication IE being set to a value indicating that an always - on PDU session is requested; and a means for receiving a PDU session establishment approval message when it is determined that the requested PDU session is not established as an always - on PDU session, the PDU session establishment approval message comprising a NAS always - on PDU session indication IE, the NAS always - on PDU session indication IE being set to a value indicating that an always - on PDU session is not permitted if the user equipment (UE) included a NAS PDU session request IE in the PDU session establishment request message, or the NAS always - on PDU session indication IE not being included if the UE did not include a NAS PDU session request IE in the PDU session establishment request message, may be provided.

[0045] In some embodiments, the apparatus may further comprise a means for considering an established PDU session as an always - on PDU session in an instance where a NAS always - on PDU session indication IE is included in the PDU session establishment approval message and the NAS always - on PDU session indication IE is set to a value indicating that an always - on PDU session is requested.

[0046] In some embodiments, the apparatus may further comprise means for not considering an established PDU session as an always-on PDU session in an instance where an always-on PDU session indication IE is included in a PDU session establishment approval message and the always-on PDU session indication IE is set to a value indicating that an always-on PDU session is not permitted.

[0047] In some embodiments, there is provided a method comprising receiving, from a user equipment (UE), a protocol data unit (PDU) session modification request message, the PDU session modification request message being configured to indicate a request to modify a PDU session corresponding to a PDN connection established in S1 mode after a first inter-system change from S1 mode to N1 mode, the PDU session modification request message comprising an information element (IE) set to a value indicating a request to make the PDU session an always-on protocol data unit (PDU) session, and determining, based on local policy or configuration, whether to make the requested PDU session an always-on PDU session.

[0048] In some embodiments, when it is determined to make the requested PDU session an always-on PDU session, the method may further comprise causing the transmission of a PDU session modification command message, the PDU session modification command message comprising an always-on PDU session indication IE, the always-on PDU session indication IE being set to a value indicating that an always-on PDU session is requested.

[0049] In some embodiments, when it is determined not to make the requested PDU session an always-on PDU session, the method may further comprise causing the transmission of a PDU session modification command message, the PDU session modification command message comprising an always-on PDU session indication IE, the always-on PDU session indication IE being set to a value indicating that an always-on PDU session is not permitted.

[0050] In some embodiments, in an instance where the always-on PDU session indication IE is included in the PDU session modification command message and the always-on PDU session indication IE is set to a value indicating that an always-on PDU session is requested, the method further comprises causing the UE to consider the PDU session as an always-on PDU session.

[0051] In some embodiments, in an instance where the always-on PDU session indication IE is included in the PDU session modification command message and the always-on PDU session indication IE is set to a value indicating that an always-on PDU session is not permitted, the method further comprises causing the UE not to consider the PDU session as an always-on PDU session.

[0052] In some embodiments, when changing between systems from S1 mode to N1 mode, based on the local policy or configuration of the SMF, determining whether the requested PDU session needs to be an always-on PDU session, and if it is determined that the requested PDU session needs to be an always-on PDU session, setting the always-on PDU session indication IE included in the PDU session modification command message to a value indicating that an always-on PDU session is requested.

[0053] In some embodiments, the method may further comprise, when changing between systems from S1 mode to N1 mode, based on the local policy or configuration of the SMF, determining whether the requested PDU session needs to be an always-on PDU session, and if it is determined that the requested PDU session does not need to be an always-on PDU session, setting the always-on PDU session indication IE included in the PDU session modification command message to a value indicating that an always-on PDU session is not permitted.

[0054] In some embodiments, an apparatus may be provided that includes at least one processor and at least one memory including computer program code, the at least one memory and the computer program code being configured to, with the processor, receive from a user equipment (UE) a protocol data unit (PDU) session modification request message, the PDU session modification request message being configured to indicate a request to modify a PDU session corresponding to a PDN connection established in S1 mode after a first inter-system change from S1 mode to N1 mode, the PDU session modification request message including an information element (IE) set to a value indicating a request to make the PDU session a always-on protocol data unit (PDU) session, and to cause the apparatus to at least determine, based on local policy or configuration, whether to make the requested PDU session an always-on PDU session.

[0055] In some embodiments, the at least one memory and the computer program code are further configured to, with the processor, cause the apparatus to transmit a PDU session modification command message if it is determined that the requested PDU session is to be an always-on PDU session, the PDU session modification command message including an always-on PDU session indication IE, the always-on PDU session indication IE being set to a value indicating that an always-on PDU session is requested.

[0056] In some embodiments, the at least one memory and the computer program code are further configured to, with the processor, cause the apparatus to transmit a PDU session modification command message if it is determined that the requested PDU session is not to be an always-on PDU session, the PDU session modification command message including an always-on PDU session indication IE, the always-on PDU session indication IE being set to a value indicating that an always-on PDU session is not permitted.

[0057] In some embodiments, at least one memory and computer program code, together with the processor, further configure the apparatus to cause the UE to consider a PDU session as an always-on PDU session in an instance where the always-on PDU session indication IE is included in the PDU session modification command and the always-on PDU session indication IE is set to a value indicating that an always-on PDU session is requested.

[0058] In some embodiments, at least one memory and computer program code, together with the processor, further configure the apparatus to cause the UE not to consider a PDU session as an always-on PDU session in an instance where the always-on PDU session indication IE is included in the PDU session modification command message and the always-on PDU session indication IE is set to a value indicating that an always-on PDU session is not permitted.

[0059] In some embodiments, at least one memory and computer program code, together with the processor, configure the apparatus to determine, based on the local policy or configuration of the SMF, whether a requested PDU session needs to be an always-on PDU session when changing the system between the S1 mode and the N1 mode, and if it is determined that the requested PDU session needs to be an always-on PDU session, further configure the always-on PDU session indication IE included in the PDU session modification command message to be set to a value indicating that an always-on PDU session is requested.

[0060] In some embodiments, at least one memory and computer program code, together with a processor, cause the apparatus, when making an inter-system change from S1 mode to N1 mode, to determine, based on the local policy or configuration of the SMF, whether the requested PDU session needs to be an always-on PDU session, and if it is determined that the requested PDU session does not need to be an always-on PDU session, further configure the always-on PDU session indication IE included in the PDU session modification command message to be set to a value indicating that "always-on PDU sessions are not permitted".

[0061] In some embodiments, there may be provided a computer program product comprising at least one non-transitory computer-readable storage medium storing computer-executable program code instructions, the computer-executable program code instructions being for receiving, from a user equipment (UE), a protocol data unit (PDU) session modification request message, the PDU session modification request message being configured to indicate a request to modify a PDU session corresponding to a PDN connection established in S1 mode after a first inter-system change from S1 mode to N1 mode, the PDU session modification request message comprising an information element (IE) set to a value indicating a request to make the PDU session an always-on protocol data unit (PDU) session, and for determining, based on a local policy or configuration, whether the requested PDU session should be an always-on PDU session.

[0062] In some embodiments, if it is determined that the requested PDU session is to be an always-on PDU session, the computer-executable program code instructions further comprise program code instructions that cause the transmission of a PDU session modification command message, the PDU session modification command message comprising an always-on PDU session indication IE, and the always-on PDU session indication IE is set to a value indicating that "an always-on PDU session is requested".

[0063] In some embodiments, if it is determined that the requested PDU session is not an always-on PDU session, the computer-executable program code instructions further comprise program code instructions that cause the transmission of a PDU session modification command message, the PDU session modification command message comprising an always-on PDU session indication IE, and the always-on PDU session indication IE being set to a value indicating that "always-on PDU session is not permitted".

[0064] In some embodiments, in an instance where the always-on PDU session indication IE is included in the PDU session modification command message and the always-on PDU session indication IE is set to a value indicating "always-on PDU session", the computer-executable program code instructions further comprise program code instructions that cause the UE to consider the PDU session as an always-on PDU session.

[0065] In some embodiments, in an instance where the always-on PDU session indication IE is included in the PDU session modification command message and the always-on PDU session indication IE is set to a value indicating that "always-on PDU session is not permitted", the computer-executable program code instructions further comprise program code instructions that cause the UE not to consider the PDU session as an always-on PDU session.

[0066] In some embodiments, the computer-executable program code instructions determine, based on the local policy or configuration of the SMF, whether the requested PDU session needs to be an always-on PDU session when changing between systems from S1 mode to N1 mode, and if it is determined that the requested PDU session needs to be an always-on PDU session, set the always-on PDU session indication IE included in the PDU session modification command message to a value indicating that "always-on PDU session is requested". The computer-executable program code instructions further comprise program code instructions for performing the above.

[0067] In some embodiments, the computer-executable program code instructions, when changing the system from S1 mode to N1 mode, determine whether the requested PDU session needs to be an always-on PDU session based on the local policy or configuration of the SMF, and if it is determined that the requested PDU session does not need to be an always-on PDU session, set the always-on PDU session indication IE included in the PDU session modification command message to a value indicating that "always-on PDU sessions are not permitted". The program code instructions further include program code instructions for doing so.

[0068] In some embodiments, there may be provided an apparatus comprising means for receiving, from a user equipment (UE), a protocol data unit (PDU) session modification request message, the PDU session modification request message being configured to indicate a request to modify a PDU session corresponding to a PDN connection established in S1 mode after the first inter-system change from S1 mode to N1 mode, the PDU session modification request message comprising an information element (IE) set to a value indicating a request to make the PDU session an always-on protocol data unit (PDU) session, and means for determining, based on the local policy or configuration, whether to make the requested PDU session an always-on PDU session.

[0069] In some embodiments, the apparatus may further comprise means for causing the transmission of a PDU session modification command message if it is determined that the requested PDU session is to be an always-on PDU session, the PDU session modification command message comprising an always-on PDU session indication IE, and the always-on PDU session indication IE being set to a value indicating that "an always-on PDU session is requested".

[0070] In some embodiments, if the apparatus determines that the requested PDU session is not a always-on PDU session, the apparatus may further comprise means for causing the transmission of a PDU session modification command message, the PDU session modification command message comprising an always-on PDU session indication IE, and the always-on PDU session indication IE being set to a value indicating that "always-on PDU sessions are not permitted".

[0071] In some embodiments, in an instance where the always-on PDU session indication IE is included in the PDU session modification command message and the always-on PDU session indication IE is set to a value indicating that "an always-on PDU session is requested", the apparatus further comprises means for causing the UE to consider the PDU session as an always-on PDU session.

[0072] In some embodiments, in an instance where the always-on PDU session indication IE is included in the PDU session modification command message and the always-on PDU session indication IE is set to a value indicating that "always-on PDU sessions are not permitted", the apparatus further comprises means for causing the UE not to consider the PDU session as an always-on PDU session.

[0073] In some embodiments, when changing between systems from S1 mode to N1 mode, the apparatus determines whether the requested PDU session needs to be an always-on PDU session based on the local policy or configuration of the SMF, and if it is determined that the requested PDU session needs to be an always-on PDU session, the apparatus further comprises means for setting the always-on PDU session indication IE included in the PDU session modification command message to a value indicating that "an always-on PDU session is requested".

[0074] In some embodiments, when the system changes between the S1 mode and the N1 mode, the apparatus further comprises means for determining, based on the local policy or configuration of the SMF, whether the requested PDU session needs to be an always-on PDU session; and means for setting the always-on PDU session indication IE included in the PDU session modification command message to a value indicating that "always-on PDU sessions are not permitted" when it is determined that the requested PDU session does not need to be an always-on PDU session.

[0075] In some embodiments, causing the transmission of a protocol data unit (PDU) session modification request message, the PDU session modification request message being configured to indicate a request to modify a PDU session corresponding to a PDN connection established in the S1 mode after the first inter-system change from the S1 mode to the N1 mode, the PDU session modification request message comprising an information element (IE) set to a value indicating a request to make the PDU session an always-on protocol data unit (PDU) session; receiving a PDU session modification command message when it is determined that the requested PDU session is to be an always-on PDU session, the PDU session modification command message comprising an always-on PDU session indication IE, the always-on PDU session indication IE being set to a value indicating that "an always-on PDU session is requested"; and receiving a PDU session modification command message when it is determined that the requested PDU session is not to be an always-on PDU session, the PDU session modification command message comprising an always-on PDU session indication IE, the always-on PDU session indication IE being set to a value indicating that "always-on PDU sessions are not permitted". A method comprising the above is provided.

[0076] In some embodiments, the method may further comprise treating a PDU session as an always-on PDU session in an instance where the always-on PDU session indication IE is included in the PDU session modification command message and the always-on PDU session indication IE is set to a value indicating that an always-on PDU session is requested.

[0077] In some embodiments, the method may further comprise not treating a PDU session as an always-on PDU session in an instance where the always-on PDU session indication IE is included in the PDU session modification command message and the always-on PDU session indication IE is set to a value indicating that an always-on PDU session is not permitted.

[0078] In some embodiments, an apparatus may be provided that includes at least one processor and at least one memory including computer program code, the at least one memory and the computer program code being configured, with the processor, to cause a transmission of a protocol data unit (PDU) session modification request message, the PDU session modification request message being configured to indicate a request to modify a PDU session corresponding to a PDN connection established in S1 mode after a first inter-system change from S1 mode to N1 mode, the PDU session modification request message including an information element (IE) set to a value indicating a request to make the PDU session a non-stop connection protocol data unit (PDU) session, and, upon determining that the requested PDU session is to be a non-stop connection PDU session, to receive a PDU session modification command message, the PDU session modification command message including a non-stop connection PDU session indication IE, the non-stop connection PDU session indication IE being set to a value indicating that a non-stop connection PDU session is requested, and, upon determining that the requested PDU session is not to be a non-stop connection PDU session, to receive a PDU session modification command message, the PDU session modification command message including a non-stop connection PDU session indication IE, the non-stop connection PDU session indication IE being set to a value indicating that a non-stop connection PDU session is not permitted, and at least to be configured to cause the apparatus to perform the above operations.

[0079] In some embodiments, the at least one memory and the computer program code are further configured, with the processor, to cause the apparatus to consider the PDU session as a non-stop connection PDU session in an instance where the non-stop connection PDU session indication IE is included in the PDU session modification command message and the non-stop connection PDU session indication IE is set to a value indicating that a non-stop connection PDU session is requested.

[0080] In some embodiments, at least one memory and computer program code, in combination with a processor, further configure the apparatus to not consider a PDU session as an always-on PDU session in an instance where an always-on PDU session indication IE is included in a PDU session modification command message and the always-on PDU session indication IE is set to a value indicating that "always-on PDU sessions are not permitted".

[0081] In some embodiments, there may be provided a computer program product comprising at least one non-transitory computer-readable storage medium storing computer-executable program code instructions, the computer-executable program code instructions causing transmission of a protocol data unit (PDU) session modification request message, the PDU session modification request message being configured to indicate a request to modify a PDU session corresponding to a PDN connection established in S1 mode after a first inter-system change from S1 mode to N1 mode, the PDU session modification request message comprising an information element (IE) set to a value indicating a request to make the PDU session an always-on protocol data unit (PDU) session, causing transmission of, upon determining that the requested PDU session is to be an always-on PDU session, receiving a PDU session modification command message, the PDU session modification command message comprising an always-on PDU session indication IE, the always-on PDU session indication IE being set to a value indicating that "an always-on PDU session is requested", receiving a PDU session modification command message, the PDU session modification command message comprising an always-on PDU session indication IE, the always-on PDU session indication IE being set to a value indicating that "always-on PDU sessions are not permitted", and comprising program code instructions for performing.

[0082] In some embodiments, the computer-executable program code instructions further comprise program code instructions that, in an instance where the always-on PDU session indication IE is included in the PDU session modification command message and the always-on PDU session indication IE is set to a value indicating that an always-on PDU session is requested, regard the PDU session as an always-on PDU session.

[0083] In some embodiments, the computer-executable program code instructions further comprise program code instructions that, in an instance where the always-on PDU session indication IE is included in the PDU session modification command message and the always-on PDU session indication IE is set to a value indicating that an always-on PDU session is not permitted, do not regard the PDU session as an always-on PDU session.

[0084] In some embodiments, means for causing transmission of a protocol data unit (PDU) session modification request message, the PDU session modification request message being configured to indicate a request to modify a PDU session corresponding to a PDN connection established in S1 mode after a first inter-system change from S1 mode to N1 mode, the PDU session modification request message comprising an information element (IE) set to a value indicating a request to make the PDU session a always-on protocol data unit (PDU) session; means for receiving a PDU session modification command message when it is determined to make the requested PDU session an always-on PDU session, the PDU session modification command message comprising an always-on PDU session indication IE, the always-on PDU session indication IE being set to a value indicating that an always-on PDU session is requested; and means for receiving a PDU session modification command message when it is determined not to make the requested PDU session an always-on PDU session, the PDU session modification command message comprising an always-on PDU session indication IE, the always-on PDU session PDU session indication IE being set to a value indicating that an always-on PDU session is not permitted, may be provided.

[0085] In some embodiments, the apparatus may further comprise means for considering the PDU session as an always-on PDU session in an instance where the always-on PDU session indication IE is included in the PDU session modification command message and the always-on PDU session indication IE is set to a value indicating that an always-on PDU session is requested.

[0086] In some embodiments, the apparatus may further comprise means for not considering the PDU session as an always-on PDU session in an instance where the always-on PDU session indication IE is included in the PDU session modification command message and the always-on PDU session indication IE is set to a value indicating that an always-on PDU session is not permitted.

[0087] We have described various embodiments of the present disclosure in general terms. Hereinafter, reference will be made to the accompanying drawings, which are not necessarily to scale.

Brief Description of the Drawings

[0088]

Fig. 1A

Fig. 1B

Fig. 2

Fig. 3

Fig. 4

Fig. 5

Fig. 6

Fig. 7

Fig. 8

Modes for Carrying Out the Invention

[0089] Some embodiments of the present invention will be described in further detail below with reference to the accompanying drawings. In the following description, only some, not all, of the present invention is shown. In fact, various embodiments of the present invention may be embodied in many different forms and should not be construed as limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like numbers refer to like elements throughout. As used herein, the terms “data,” “content,” “information,” and similar terms may be used interchangeably to refer to data that can be transmitted, received, and / or stored by embodiments of the present invention. Thus, the use of such terms should not be regarded as limiting the spirit and scope of embodiments of the present invention.

[0090] Further, as used herein, the term “circuit” refers to (a) a circuit implementation of only hardware (e.g., implementation in analog and / or digital circuits), (b) a combination of a circuit and one or more computer program products including software and / or firmware instructions stored in one or more computer-readable memories, which cooperate to cause an apparatus to perform one or more of the functions described herein, and (c) a circuit that requires software or firmware for operation even when software or firmware is not physically present, such as, for example, a microprocessor(s) or a portion of a microprocessor(s). This definition of “circuit” applies to all uses of this term in this document, including in the claims. As a further example, as used herein, the term “circuit” also includes an implementation including one or more processors and / or a portion thereof, and associated software and / or firmware. As another example, the term “circuit” as used herein includes, for example, a baseband integrated circuit or an application processor integrated circuit for a mobile phone, or a similar integrated circuit of a server, a cellular network device, other network devices, a field programmable gate array, and / or other computing devices.

[0091] As defined herein, a "computer-readable storage medium," which refers to a physical storage medium (e.g., a volatile or non-volatile memory device), may be distinguished from a "computer-readable transmission medium," which refers to an electromagnetic signal.

[0092] A method, apparatus, and computer program product may be provided to provide an always-on connection as an attribute of a PDU session. A method, apparatus, and computer program product may also be provided to provide an interworking aspect for an always-on connection PDU session. A method, apparatus, and computer program product may also be provided to provide a function to enable a network to determine whether a PDU session may be an always-on connection PDU session.

[0093] Referring now to FIG. 1, an exemplary system is shown that supports communication between a plurality of stations 10 and one or more wireless base stations / access points 12 (e.g., a plurality of wireless base stations / access points may be deployed in a geographical area, a high-density system scenario where they may operate on the same frequency channel), where each wireless base station / access point may communicate with one or more stations and, in one embodiment, may communicate with a large number of stations. Next, the wireless base station / access point may communicate with a network 14. The wireless base station / access point may communicate via a 5G, Long-Term Evolution (LTE), or LTE-Advanced (LTE-A) network, although other networks may support communication between access points. Other networks include Wideband Code Division Multiple Access (W-CDMA), CDMA2000, Global System for Mobile Communications (GSM), General Packet Radio Service (GPRS), for example, IEEE802.11ah or 802.11ac standards, or IEEE802.11 standards including modifications of other newer standards, Wireless Local Area Network (WLAN), WiMAX (Worldwide Interoperability for Microwave Access) protocol, Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (UTRAN), etc., and networks configured according to other standards related to multi-domain networks that may include industrial wireless communication networks such as WirelessHART, Bluetooth, ZigBee, etc.

[0094] The wireless base station / access point 12 and the station 10 may communicate via wired communication, but most commonly may communicate via wireless communication. For example, the wireless base station / access point and the station may communicate in the sub-1 GHz band defined by the IEEE802.11ah standard, or, for example, in the 5 GHz band that may be defined by the IEEE802.11ac standard. The wireless base station / access point may be embodied by any of various network entities such as an access point, a base station, a Node B, an evolved Node B (eNB), a Radio Network Controller (RNC), a Mobile Device / Station (e.g., a mobile phone, a smartphone, a Portable Digital Assistant (PDA), a pager, a laptop computer, a tablet computer, or many other handheld or portable communication devices, computing devices, content generation devices, content consumption devices, or combinations thereof). The station may also be embodied by various devices such as sensors, meters, etc. The sensors and meters may be deployed in various different applications including utility applications that function as gas meters, water meters, power meters, etc., environmental and / or agricultural monitoring applications, industrial process automation applications, vehicle or transportation automation applications, healthcare and fitness applications, building automation and control applications, and / or temperature sensing applications. The station embodied by a sensor or a meter may, in some embodiments, be utilized to backhaul the data of the sensors and meters. Alternatively, the station may be embodied by a mobile terminal or a User Equipment (UE) such as, for example, a mobile communication device such as a mobile phone, a smartphone, a Portable Digital Assistant (PDA), a pager, a laptop computer, a tablet computer, or any of many other handheld or portable communication devices, computing devices, content generation devices, content consumption devices, or combinations thereof.In an embodiment where the station is embodied by a mobile terminal, the communication between the access point and the station may be useful for extending the range of Wi-Fi or other wireless local area network (WLAN), for example, by extending the range of a hot spot, and if not extended, may be useful for offloading traffic that would otherwise be carried by a cellular or other network.

[0095] The radio base station / access point 12 and / or the station 10 may be embodied as, or may include, the device 20. The device 20 is specifically configured to perform the functions of each device generally represented by the block diagram of FIG. 2. The device may be employed, for example, by a radio base station / access point or a station, but it should be noted that the components, devices or elements described below are not essential, and thus some may be omitted in a particular embodiment. Further, some embodiments may include components, devices, or elements different from or additional to those shown and described herein.

[0096] FIG. 1B shows the principle of the 5G architecture in the current draft 3GPP specification. In particular, FIG. 1B shows a networked system 100 according to an exemplary embodiment of the present disclosure. FIG. 1B specifically shows a user equipment (UE) 102 that can communicate with a radio access network (RAN) 104, an access and mobility management function (AMF) 108, and a user plane function (UPF) 106. Next, the AMF 108 may communicate with core network services including a session management function (SMF) 110 and a policy control function (PCF) 114. The core network services may also communicate with an application server / application function (AS / AF) 112. Other network services also include a network slice selection function (NSSF) 122, an authentication server function (AUSF) 120, a user data management (UDM) 118, and a data network (DN) 116.

[0097] Regardless of the type of device that embodies any of the network devices including, but not limited to, the radio base station / access point 12 and / or the station 10, the UE 102, the SMF 110, or any of the other devices shown in the figure, any of the radio base station / access point 12 and / or the station 10, the UE 102, or any of the other devices shown in the figure may include, or be associated with, the apparatus 20. In this regard, the apparatus may include, or communicate with, a processor 22, a memory device 24, and a communication interface 26. Thus, in some embodiments, devices or elements are shown as communicating with each other, but hereinafter, such devices or elements should be considered as being able to be embodied within the same device or element, and thus, devices or elements shown as communicating should alternatively be understood as being part of the same device or element.

[0098] In some embodiments, the processor 22 (and / or a coprocessor or other arbitrary processing circuitry that supports or is associated with the processor) may communicate with the memory device 24 via a bus for communicating information among the components of the device. The memory device may include, for example, one or more volatile and / or non-volatile memories. In other words, for example, the memory device may be an electronic storage device (e.g., a computer-readable storage medium) including gates configured to store data (e.g., bits) that may be retrievable by a machine (e.g., a computing device such as a processor). The memory device may be configured to store information, data, content, applications, instructions, etc. for enabling the apparatus 20 to perform various functions according to exemplary embodiments of the present invention. For example, the memory device may be configured to buffer input data for processing by the processor. Additionally or alternatively, the memory device may be configured to store instructions for execution by the processor.

[0099] As described above, apparatus 20 may be embodied by a computing device 10 configured to employ an exemplary embodiment of the present invention. However, in some embodiments, the apparatus may be embodied as a chip or a chipset. In other words, the apparatus may include one or more physical packages (e.g., chips) that include materials, components, and / or wires on a structural assembly (e.g., a motherboard). The structural assembly may provide physical strength, size conservation, and / or limitation of electrical interaction for the component circuits included therein. Thus, the apparatus may, in some cases, be configured to implement an embodiment of the present invention on a single chip or as a single “system on a chip”. Thus, in some cases, a chip or a chipset may constitute means for performing one or more operations for providing the functions described herein.

[0100] Processor 22 may be embodied in several different ways. For example, the processor may be embodied as one or more of various hardware processing means such as a coprocessor, a microprocessor, a controller, a digital signal processor (DSP), a processing element with or without an accompanying DSP, or various other processing circuits including integrated circuits such as, for example, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), a microcontroller unit (MCU), a hardware accelerator, a dedicated computer chip, etc. Thus, in some embodiments, the processor may include one or more processing cores configured to execute independently. A multi-core processor may enable multi-processing within a single physical package. Additionally or alternatively, the processor may include one or more processors configured in tandem via a bus to enable independent execution of instructions, pipelines, and / or multi-threading.

[0101] In an exemplary embodiment, the processor 22 may be configured to execute instructions stored in the memory device 24 or accessible to the processor. Alternatively or additionally, the processor may be configured to execute hard-coded functions. Thus, whether configured by a hardware or software approach, or a combination thereof, the processor may represent an entity that, while being configured accordingly, can perform operations according to embodiments of the present invention (e.g., physically embodied in circuitry). Thus, for example, if the processor is embodied as an ASIC, FPGA, etc., the processor may be hardware specifically configured to perform the operations described herein. Or, as another example, if the processor is embodied as an executor of software instructions, the instructions may specifically configure the processor to perform the algorithms and / or operations described herein when the instructions are executed. However, in some cases, the processor may be the processor of a particular device configured to adopt embodiments of the present invention by further configuring the processor with instructions for performing the algorithms and / or operations described herein. The processor may include, among other things, a clock, an arithmetic logic unit (ALU), and logic gates configured to support the operation of the processor.

[0102] On the one hand, the communication interface 26 may be any means, such as a device or circuit embodied in either hardware or a combination of hardware and software, configured to receive and / or transmit data between the computing device 10 and the server 12. In this regard, the communication interface 26 may include, for example, an antenna (or antennas) and support hardware and / or software to enable wireless communication. Additionally or alternatively, the communication interface may include circuitry that interacts with the antenna(s) to transmit signals via the antenna(s) or to process the reception of signals received via the antenna(s). For example, the communication interface may be configured to communicate wirelessly with the head-mounted display 10, such as via Wi-Fi, Bluetooth, or other wireless communication technologies. In some cases, the communication interface may alternatively or additionally support wired communication. Thus, for example, the communication interface may include a communication modem and / or other hardware / software to support communication via a cable, digital subscriber line (DSL), universal serial bus (USB), or other mechanism. For example, the communication interface may be configured to communicate with other components of the computing device via wired communication.

[0103] FIG. 3 shows a data flow diagram illustrating an exemplary embodiment of the present invention. In particular, FIG. 3 shows the start of a PDU session establishment procedure initiated by a UE, followed by an SMF response. For example, in some embodiments, the UE may initiate a PDU session establishment procedure requested by the UE. When the UE requests the establishment of a new always-on PDU session, the UE includes the always-on PDU session requested information element (IE) and sets the value of the IE to, for example, "an always-on PDU session is requested". Thus, as shown at 305, UE 102 may provide a PDU session establishment request message to SMF 110. Thereafter, also at 305, SMF 110 receives a PDU session establishment request message from UE 102. The PDU session establishment request message may include the always-on PDU session requested IE, and the always-on PDU session requested IE is set to a value such as "an always-on PDU session is requested".

[0104] Following reception of the always-on PDU session requested IE of a PDU session establishment request message set to a value such as "an always-on PDU session is requested", a determination may be made, for example, based on the local policy or configuration of the SMF. That is, as shown in step 310 of FIG. 3, following reception of a PDU session establishment request message from the UE, the SMF may provide a PDU session establishment approval message to the UE. In some embodiments, for example, if the SMF determines that the requested PDU session needs to be established as an always-on PDU session, the SMF includes an always-on PDU session indication IE in the PDU session establishment approval message and sets the value to "an always-on PDU session is requested". In some embodiments, for example, if the SMF determines that the requested PDU session is not to be established as an always-on PDU session and the UE includes the IE requested for the always-on PDU session, the SMF includes the always-on PDU session indication IE in the PDU session establishment approval message and sets the value to "an always-on PDU session is not permitted". In some embodiments, for example, if the SMF determines that the requested PDU session is not to be established as an always-on PDU session and the UE did not include the IE requested for the always-on PDU session, the SMF does not include the always-on PDU session indication IE in the PDU session establishment approval message.

[0105] After that, if the always-on PDU session indication IE is included in the PDU session establishment approval message and the value is set to "always-on PDU session is requested", the UE shall consider the established PDU session as an always-on PDU session. However, if the always-on PDU session indication IE is included in the PDU session establishment approval message but the value is set to "always-on PDU session is not permitted", the UE shall not consider the established PDU session as an always-on PDU session. If the UE does not receive the always-on PDU session indication IE in the PDU session establishment approval message, the UE shall not consider the established PDU session as an always-on PDU session.

[0106] Regarding the inter-system change from N1 mode to S1 mode, after the inter-system change from N1 mode to S1 mode, the UE and the SMF shall maintain the always-on PDU session indication. When the UE returns to 5GS (i.e., the inter-system change from S1 mode to N1 mode), the UE and the SMF may determine whether the PDU session transferred from EPS is an always-on PDU session by using the always-on PDU session indication.

[0107] Regarding the inter-system change from S1 mode to N1 mode, when changing from S1 mode to N1 mode in 5GMM-IDLE mode, the UE shall set the always-on PDU session indication, if any, to the always-on PDU session maintained by the UE.

[0108] Figures 5 and 6 show operations performed, for example, by an apparatus embodied by an SMF and a UE, respectively, to utilize, for example, a PDU session establishment procedure, and in particular, to provide and / or utilize always-on connectivity as an attribute of the PDU session and to provide aspects of interworking with respect to an always-on connectivity PDU session. That is, in another exemplary embodiment, to provide a procedure for establishing a PDU session, and in particular, to determine whether to utilize always-on connectivity as an attribute of the PDU session to provide an always-on connectivity PDU session, and if it is determined to provide an always-on connectivity PDU session, a method, apparatus, and / or computer program product for providing the always-on connectivity PDU session may be provided. FIG. 5 is an exemplary flowchart showing a method of operating an exemplary apparatus, for example, apparatus 200, embodied by an SMF 110, performed in accordance with an embodiment of the present invention.

[0109] In an exemplary embodiment, apparatus 20 includes means such as a processor 210 configured to receive, from a UE, a PDU session establishment request message. In some embodiments, the PDU session establishment request message may be configured to indicate a request to establish a new PDU session. In some embodiments, the PDU session establishment request message may include an IE set to a value indicating a request to establish a new always-on connectivity PDU session. Refer to block 405 of FIG. 4.

[0110] Thereafter, as described above, the determination may be made. Thus, the apparatus 200 includes means such as a processor 210 configured to determine, based on a local policy or configuration, whether the requested PDU session is to be established as an always-on PDU session. Refer to block 410 in FIG. 4. The determination may result in a determination that the requested PDU session is to be established as an always-on PDU session, or that the requested PDU session is not to be established as an always-on PDU session. Thus, the apparatus 20 includes means such as a processor 210 configured to cause the transmission of a PDU session establishment approval message based on the determination that the requested PDU session is to be established as an always-on PDU session. The PDU session establishment approval message includes an always-on PDU session indication IE, and the always-on PDU session indication IE is set to a value indicating that an always-on PDU session is requested. Refer to block 415 in FIG. 4. The apparatus 20 includes means such as a processor 210 configured to cause the transmission of a PDU session establishment approval message based on the determination that the requested PDU session is not to be established as an always-on PDU session. The PDU session establishment approval message includes an always-on PDU session indication IE, and the always-on PDU session indication IE is set to a value indicating that an always-on PDU session is not permitted. Refer to block 420 in FIG. 4.

[0111] As an effect that the always-on PDU session indication IE is set to either "always-on PDU session is requested" or "always-on PDU session is not permitted", the UE is notified of the status of the newly established PDU session. The apparatus 20 includes means such as a processor 210 configured to cause the established PDU session to be regarded as an always-on PDU session and the UE in an instance where the always-on PDU session indication IE is included in the PDU session establishment approval message and the always-on PDU session indication IE is set to a value indicating "always-on PDU session is requested". Refer to block 425 in FIG. 4. The apparatus 20 includes means such as a processor 210 configured to prevent the established PDU session from being regarded as an always-on PDU session and the UE in an instance where the always-on PDU session indication IE is included in the PDU session establishment approval message and the always-on PDU session indication IE is set to a value indicating "always-on PDU session is not permitted". Refer to block 430 in FIG. 4.

[0112] The apparatus 20 includes means such as a processor 210 configured to maintain the always-on PDU session indication in the UE and the SMF when changing the system between the N1 mode and the S1 mode. Refer to block 435 in FIG. 4. The apparatus 20 includes means such as a processor 210 configured to determine whether the PDU session transferred from the evolved packet system (EPS) is an always-on PDU session based on the always-on PDU session indication when changing the system from the S1 mode to the N1 mode. Refer to block 440 in FIG. 4.

[0113] FIG. 5 is a flowchart illustrating an exemplary embodiment for requesting an always-on PDU session. Specifically, the UE may initiate the PDU session establishment procedure requested by the UE. For example, in an instance where the UE is configured to establish a new always-on PDU session, the UE may include the information element (IE) requested for the always-on PDU session, and set the value of the IE to, for example, "an always-on PDU session is requested". The operations performed by apparatus 200 to request an always-on PDU session using the always-on PDU session attribute IE of the PDU session are shown in the flowchart of FIG. 5.

[0114] Apparatus 20 includes means such as a processor 210 configured to cause the transmission of a protocol data unit (PDU) session establishment request message. In some embodiments, for example, in an embodiment where the UE is configured to require an always-on PDU session, the PDU session establishment request message may be configured to indicate a request to establish a new PDU session, whereby the PDU session establishment request message includes an IE set to a value indicating a request to establish a new always-on PDU session. Refer to block 505 of FIG. 5.

[0115] When transmitting the PDU session establishment request message, for example, the determination may be made by the SMF. If apparatus 20 determines that the requested PDU session is to be established as an always-on PDU session, it includes means such as a processor 210 configured to receive a PDU session establishment approval message, the PDU session establishment approval message including an always-on PDU session indication IE, and the always-on PDU session indication IE is set to a value indicating that "an always-on PDU session is requested". Refer to block 510 of FIG. 5.

[0116] The apparatus 20 may also include means such as a processor 210 configured to receive a PDU session establishment approval message, for example, by an SMF, if it is determined that the requested PDU session is not established as an always-on PDU session. The PDU session establishment approval message includes an always-on PDU session indication IE, and the always-on PDU session indication IE is set to a value indicating that "always-on PDU session is not permitted". Refer to block 515 of FIG. 5.

[0117] The apparatus 20 includes means such as a processor 210 configured to consider an established PDU session as an always-on PDU session in an instance where the always-on PDU session indication IE is included in the PDU session establishment approval message and the always-on PDU session indication IE is set to a value indicating that "an always-on PDU session is requested". Refer to block 520 of FIG. 5. The apparatus 20 includes means such as a processor 210 configured not to consider an established PDU session as an always-on PDU session in an instance where the always-on PDU session indication IE is included in the PDU session establishment approval message and the always-on PDU session indication IE is set to a value indicating that "always-on PDU session is not permitted". Refer to block 525 of FIG. 5.

[0118] FIG. 6 shows a data flow diagram illustrating an exemplary embodiment of the present invention. Specifically, FIG. 6 shows a PDU session modification procedure. For example, in some embodiments, for a PDN connection established in S1 mode (i.e., the UE and the SMF do not have a maintained always-on PDU session indication), after the first inter-system change from S1 mode to N1 mode (e.g., 605 in FIG. 6), if the UE is operating in single registration mode in a network that does not support interworking without N26, and the UE requests to make the PDN connection an always-on PDU session in 5GS, the UE includes an always-on PDU session requested IE and sets the value of the IE to "always-on PDU session is requested". Refer to 610 of FIG. 6.

[0119] After that, the SMF determines whether the requested PDU session is established as an always-on PDU session. Once the determination is made, the SMF may provide, for example, a PDU session establishment command message to the UE. Refer to 615 in FIG. 6. Specifically, for a PDN connection established in S1 mode, at the first inter-system change from S1 mode to N1 mode, the PDU session modification procedure requested by the network is triggered by the PDU session modification procedure requested by the UE. When the SMF determines, based on the SMF's local policy or configuration and the always-on PDU session modification request message (if present) within the PDU session modification request message, that the requested PDU session needs to be an always-on PDU session, the SMF includes an always-on PDU session indication IE in the PDU session modification command message and sets the value to "always-on PDU session is requested". Alternatively, for a PDN connection established in S1 mode, at the first inter-system change from S1 mode to N1 mode, the PDU session modification procedure requested by the network is triggered by the PDU session modification procedure requested by the UE. When the SMF determines, based on the SMF's local policy or configuration and the always-on PDU session requested IE (if present) of the PDU session modification request message, that the requested PDU session is not to be an always-on PDU session, and the UE includes the always-on PDU session requested IE, the SMF includes an always-on PDU session indication IE in the PDU session modification command message and sets the value to "always-on PDU session is not permitted".

[0120] In these embodiments where the PDU session modification procedure requested by the network is triggered by the PDU session modification procedure requested by the UE for the PDN connection established in S1 mode during the first inter-system change from S1 mode to N1 mode, the SMF determines, based on the SMF's local policy or configuration and the always-on PDU session requested IEs (if any) in the PDU session modification request message, that the requested PDU session is not to be an always-on PDU session. If the UE does not include the always-on PDU session requested IEs, the SMF does not include the always-on PDU session indication IE in the PDU session modification command message.

[0121] Subsequently, if the always-on PDU session indication IE is included in the PDU session modification command message and the value is set to "always-on PDU session is requested", the UE regards the established PDU session as an always-on PDU session. On the other hand, if the always-on PDU session indication IE is included in the PDU session modification command message and the value is set to "always-on PDU session is not permitted", the UE does not regard the established PDU session as an always-on PDU session. If the UE does not receive the always-on PDU session indication IE in the PDU session modification command message, the UE does not regard the modified PDU session as an always-on PDU session.

[0122] In some embodiments, for the PDN connection established in S1 mode, when making the first inter-system change from S1 mode to N1 mode, if the SMF determines, based on the SMF's local policy or configuration, that the requested PDU session needs to be an always-on PDU session, the SMF includes the always-on PDU session indication IE in the PDU session modification command message and sets the value to "always-on PDU session is requested".

[0123] On the one hand, for the PDN connection established in S1 mode, when making the first inter-system change from S1 mode to N1 mode, if the SMF determines, based on its local policy or configuration, that it will not make the requested PDU session a always-on PDU session, the SMF shall include the always-on PDU session indication IE in the PDU session modification command message and set the value to "always-on PDU session is not permitted". Otherwise, the SMF shall not include the always-on PDU session indication IE in the PDU session modification command message.

[0124] Finally, when the always-on PDU session indication IE is included in the PDU session modification command message and the value is set to "always-on PDU session is requested", the UE shall consider the PDU session as an always-on PDU session. In an instance where the always-on PDU session indication IE is included in the PDU session modification command message and the value is set to "always-on PDU session is not permitted", the UE shall not consider the PDU session as an always-on PDU session. In this case, the UE may be configured to ignore the indication from the upper layer for the always-on PDU session and notify the upper layer that the indication regarding the always-on PDU session is ignored.

[0125] FIG. 7 and FIG. 8 show operations performed by devices embodied by the SMF and the UE respectively, for example, to provide modification procedures for a PDN connection established in S1 mode. That is, in another exemplary embodiment, a method, apparatus, and / or computer program product for providing modification procedures for a PDN connection established in S1 mode may be provided. FIG. 7 is an exemplary flowchart showing a method of operating an exemplary device, for example, device 200, embodied by, for example, SMF 110, performed in accordance with an embodiment of the present invention.

[0126] In an exemplary embodiment, the apparatus 200 comprises means such as a processor 210 configured to receive, from a UE, a PDU session modification request message, the PDU session modification request message being configured to indicate a request to modify a PDU session corresponding to a PDN connection established in S1 mode after a first inter-system change from S1 mode to N1 mode, the PDU session modification request message comprising an IE set to a value indicating a request to make the PDU session an always-on PDU session, or the PDU session modification request message not comprising an IE requested for an always-on PDU session. Refer to block 705 of FIG. 7. In an exemplary embodiment, the apparatus 200 comprises means such as a processor 210 configured to determine, based on the local policy or configuration and the IE requested for an always-on PDU session in an instance where the IE requested for an always-on PDU session is available, whether to make the requested PDU session an always-on PDU session. Refer to block 710 of FIG. 7.

[0127] In an exemplary embodiment, if the apparatus 200 determines to make the requested PDU session an always-on PDU session, it comprises means such as a processor 210 configured to trigger the transmission of a PDU session modification command message, the PDU session modification command message comprising an always-on PDU session indication IE, the always-on PDU session indication IE being set to a value indicating that an always-on PDU session is requested. Refer to block 715 of FIG. 7. The apparatus 200 may also comprise means such as a processor 210 configured to trigger the transmission of a PDU session modification command message if it determines not to make the requested PDU session an always-on PDU session, the PDU session modification command message comprising an always-on PDU session indication IE if the UE included the IE requested for an always-on PDU session in the PDU session establishment request message, or not comprising an always-on PDU session indication IE if the UE did not include the IE requested for an always-on PDU session in the PDU session establishment request message. Refer to block 720 of FIG. 7.

[0128] Thereafter, in an exemplary embodiment, the apparatus 200 includes means such as a processor 210 configured to cause the UE to consider a PDU session as an always-on PDU session in an instance where the always-on PDU session indication IE is not included in the PDU session modification command message, or where the always-on PDU session indication IE is included in the PDU session modification command message and the always-on PDU session indication IE is set to a value indicating that an always-on PDU session is requested. Refer to block 725 in FIG. 7. The apparatus 200 may also include means such as a processor 210 configured to cause the UE not to consider a PDU session as an always-on PDU session in an instance where the always-on PDU session indication IE is included in the PDU session modification command message and the always-on PDU session indication IE is set to a value indicating that an always-on PDU session is not permitted. Refer to block 730 in FIG. 7.

[0129] In an exemplary embodiment, when changing between systems from S1 mode to N1 mode, the apparatus 200 determines, based on the local policy or configuration of the SMF, whether the requested PDU session needs to be an always-on PDU session. If it is determined that the requested PDU session needs to be an always-on PDU session, the apparatus 200 includes means such as a processor 210 configured to set the always-on PDU session indication IE included in the PDU session modification command message to a value indicating that an always-on PDU session is requested. Refer to block 735 in FIG. 7.

[0130] In an exemplary embodiment, when changing between system modes from S1 mode to N1 mode, the apparatus 200 determines, based on the local policy or configuration of the SMF, whether the requested PDU session needs to be an always-on PDU session. If it is determined that the requested PDU session does not need to be an always-on PDU session, means such as the processor 210 configured to set the always-on PDU session indication IE included in the PDU session modification command message to a value indicating that "always-on PDU sessions are not permitted" are provided. Refer to block 740 in FIG. 7.

[0131] As described above, FIG. 8 shows operations performed by, for example, an apparatus embodied by a UE, regarding the procedure for modifying a PDN connection established in S1 mode. That is, in another exemplary embodiment, a method, apparatus, and / or computer program product for enabling the procedure for modifying a PDN connection established in S1 mode may be provided. FIG. 8 is an exemplary flowchart showing a method of operating an exemplary apparatus, for example, apparatus 200, embodied by UE102 and implemented according to an embodiment of the present invention.

[0132] In an exemplary embodiment, the apparatus 200 includes means such as the processor 210 configured to trigger the transmission of a PDU session modification request message, and the PDU session modification request message is configured to indicate a request to modify the PDU session corresponding to the PDN connection established in S1 mode after the first inter-system change from S1 mode to N1 mode. In some embodiments, the PDU session modification request message may include an IE, and the value of the IE is set to a value indicating a request to make the PDU session an always-on PDU session, or the PDU session modification request message does not include the IE for which an always-on PDU session is requested. Refer to block 805 in FIG. 8.

[0133] After that, the SMF determines whether the requested PDU session is to be a permanently connected PDU session. Once the determination is made, the SMF may, for example, provide a PDU session modification command message to the UE. In an exemplary embodiment, when the apparatus 200 determines to make the requested PDU session a permanently connected PDU session, the apparatus 200 includes means such as a processor 210 configured to receive a PDU session modification command message. The PDU session modification command message includes a permanently connected PDU session indication IE, and the permanently connected PDU session indication IE is set to a value indicating that a permanently connected PDU session is requested. Refer to block 810 in FIG. 8.

[0134] When the apparatus 200 determines not to make the requested PDU session a permanently connected PDU session, the apparatus 200 may include means such as a processor 210 configured to receive a PDU session modification command message. The PDU session modification command message includes a permanently connected PDU session indication IE. When the UE includes the IE indicating that a permanently connected PDU session is requested in the PDU session modification request message, the permanently connected PDU session indication IE is set to a value indicating that a permanently connected PDU session is not permitted. Or, when the UE does not include the IE indicating that a permanently connected PDU session is requested in the PDU session modification request message, the permanently connected PDU session indication IE is not included. Refer to block 815 in FIG. 8.

[0135] After that, in an exemplary embodiment, when the permanently connected PDU session indication IE is included in the PDU session modification command message and the permanently connected PDU session indication IE is set to a value indicating that a permanently connected PDU session is requested, the apparatus 200 includes means such as a processor 210 configured to regard the PDU session as a permanently connected PDU session. Refer to block 820 in FIG. 8.

[0136] The apparatus 200 may also include means such as a processor 210 configured not to consider a PDU session as an always-on PDU session in an instance where an always-on PDU session indication IE is included in a PDU session modification command message and the always-on PDU session indication IE is set to a value indicating that an always-on PDU session is not permitted. Refer to block 825 in FIG. 8.

[0137] As described above, FIGS. 4, 5, 7, and 8 are flowcharts of an apparatus, a method, and a computer program product according to an exemplary embodiment of the present invention. It will be understood that each block of the flowchart, and combinations of blocks in the flowchart, may be implemented by various means, such as hardware, firmware, processors, circuits, and / or other devices associated with the execution of software including one or more computer program instructions. For example, one or more of the above-described procedures may be embodied by computer program instructions. In this regard, the computer program instructions embodying the above-described procedures may be stored by a memory device of an apparatus employing an embodiment of the present invention and executed by a processor of the apparatus. As will be understood, any such computer program instructions may be loaded onto a computer or other programmable device (e.g., hardware) to produce a machine, resulting in the computer or other programmable device implementing the functions specified in the flowchart blocks. These computer program instructions may also be stored in a computer-readable memory, instructing the computer or other programmable device to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture, the execution of which implements the functions specified in the flowchart blocks. The computer program instructions may also be loaded onto a computer or other programmable device to execute a series of operational steps on the computer or other programmable device to produce a computer-implemented process, such that the instructions executed on the computer or other programmable device provide operations for implementing the functions specified in the flowchart blocks.

[0138] Accordingly, a computer program product is defined as an example in which computer program instructions, such as a computer program code portion, are stored by at least one non-transitory computer-readable storage medium and, when executed, are configured to perform the functions described above in conjunction with the flowcharts of FIGS. 4, 5, 7, and 8 and the like. In other embodiments, computer program instructions, such as a computer program code portion, need not be stored or otherwise embodied by a non-transitory computer-readable storage medium, but instead may be embodied by a transitory medium, and still, when the computer program instructions, such as a computer program code portion, are executed, are configured to perform the above functions.

[0139] Accordingly, the blocks of the flowchart support a combination of means for performing the specified function and a combination of acts for performing the specified function. It will also be understood that one or more blocks of the flowchart and combinations of blocks of the flowchart may be implemented by a dedicated hardware-based system that performs the specified function or a combination of dedicated hardware and computer instructions.

[0140] In some embodiments, certain ones of the above acts may be modified or further enhanced. Further, in some embodiments, additional optional acts may be included. Modifications, additions, or enhancements to the above acts may be made in any order and in any combination.

[0141] Those skilled in the art of the present invention, who will benefit from the teachings presented in the foregoing description and the related drawings, will envision many modifications and other embodiments of the present invention described herein. Accordingly, it is to be understood that the present invention should not be limited to the specific embodiments disclosed, and that modifications and other embodiments are intended to be included within the scope of the appended claims. Further, the foregoing description and the related drawings illustrate exemplary embodiments in the context of specific exemplary combinations of elements and / or functions, but it is to be understood that different combinations of elements and / or functions may be provided by alternative embodiments without departing from the scope of the appended claims. In this regard, for example, combinations of elements and / or functions different from those explicitly described above may also be contemplated, as set forth in some of the appended claims. Although specific terms are employed herein, they are used only in a general and descriptive sense and not for purposes of limitation.

Claims

1. 1. A method for performing a service request procedure, said method comprising: receiving a protocol data unit (PDU) session establishment request message from a user equipment (UE), the PDU session establishment request message configured to indicate a request to establish a PDU session, the PDU session establishment request message comprising an always-on PDU session requested information element (IE), the always-on PDU session requested IE indicating whether the UE requests the PDU session to be established as an always-on PDU session; In an instance where the Always Connected PDU Session Requested IE is set to a value indicating the request to establish the PDU session as a Always Connected PDU session, determining whether to establish the requested PDU session as a Always Connected PDU session based on the Always Connected PDU Session Requested IE and a local policy or configuration in a Session Management Function (SMF); In an instance where it is determined that the requested PDU session will be established as a permanent PDU session, triggering transmission of a PDU session establishment acknowledgement message to the UE, wherein the PDU session establishment acknowledgement message comprises a permanent PDU session indication IE, and the permanent PDU session indication IE is set to a value indicating "a permanent PDU session is requested"; and In an instance where it is determined that the requested PDU session will not be established as a permanent connection PDU session, causing transmission of the PDU session establishment acknowledgement message including the permanent connection PDU session indication IE, wherein the permanent connection PDU session indication IE is set to another value indicating that the PDU session request is to be established as a non-permanent connection PDU session; A method comprising:

2. Establishing the requested PDU session as a permanently connected PDU session in N1 mode; The method of claim 1 further comprising:

3. Maintaining the always-on PDU session indication IE during an inter-system change from N1 mode to S1 mode; The method of claim 1 further comprising:

4. When an inter-system change from S1 mode to N1 mode occurs, determining whether the PDU session transferred from an evolved packet system (EPS) is a constant connection PDU session based on the constant connection PDU session indication IE; The method of claim 1 further comprising:

5. 10. An apparatus comprising at least one processor and at least one memory containing computer program code, the at least one memory and the computer program code being configured, together with the processor, to cause the apparatus to perform a method according to any one of claims 1 to 4.

6. 5. A computer program product, the computer program product comprising at least one non-transitory computer-readable storage medium having computer-executable program code instructions stored thereon, the computer-executable program code instructions comprising program code instructions for performing the method of any one of claims 1 to 4.

7. 1. A method for performing a service request procedure, comprising: Triggering the transmission of a message comprising a Protocol Data Unit (PDU) Session Establishment Request and a Always-On PDU Session Requested Information Element (IE), wherein the Always-On PDU Session Requested IE is set to a value indicating a request to establish the PDU session as a Always-On PDU session; Receiving a PDU session establishment acknowledgement message including a permanently connected PDU session indication IE in response to the PDU session establishment request; In an instance where the always-on PDU session indication IE is set to a first value, determining that the PDU session will be established as a always-on PDU session; In an instance where the always-on PDU session indication IE is set to a second value, determining that the PDU session will not be established as a always-on PDU session; A method comprising:

8. In an instance where the PDU session is to be established as a permanently connected PDU session in N1 mode, upon an inter-system change from the N1 mode to the S1 mode, maintaining the permanently connected PDU session indication IE to indicate that the PDU session is a permanently connected PDU session; In an instance where the PDU session is to be established as a permanent PDU session in the S1 mode, when transferring from an evolved packet system (EPS) to a current system, determining that the PDU session is a permanent PDU session based at least on the permanent PDU session indication IE; The method of claim 7 further comprising:

9. In an instance where the always-on PDU session indication IE is included in the PDU session establishment acknowledgement message and the always-on PDU session indication IE is set to a value indicating "always-on PDU session is requested", the established PDU session is regarded as a always-on PDU session. The method of claim 8 further comprising:

10. In an instance where the always-on PDU session indication IE is included in the PDU session establishment acknowledgement message and the always-on PDU session indication IE is set to a value indicating "always-on PDU session is not permitted", the established PDU session is not considered as a always-on PDU session. The method of claim 8 further comprising:

11. 11. An apparatus comprising at least one processor and at least one memory containing computer program code, the at least one memory and the computer program code being configured, together with the processor, to cause the apparatus to perform a method according to any one of claims 7 to 10.

12. 11. A computer program product, said computer program product comprising at least one non-transitory computer readable storage medium having computer executable program code instructions stored thereon, said computer executable program code instructions comprising program code instructions for performing the method of any one of claims 7 to 10.

13. 1. A method for performing a service request procedure, comprising: receiving a Protocol Data Unit (PDU) Session Modification Request message from a User Equipment (UE), the PDU Session Modification Request message configured to indicate a PDU session for a Packet Data Network (PDN) connection established during S1 mode after an inter-system change from S1 mode to N1 mode, the PDU Session Modification Request message comprising an Information Element (IE) set to a value indicating a request that the PDU session be a Always Connected PDU session; Determining whether the requested PDU session will be a permanent PDU session in an instance where the permanent PDU session requested IE is available based on a local policy or configuration in a Session Management Function (SMF); A method comprising:

14. In an instance where the result of the determining is to determine that the requested PDU session will be a permanent PDU session, the method further comprises: Triggering the transmission of a PDU session modification command message, wherein the PDU session modification command message comprises a permanent connection PDU session indication IE, and the permanent connection PDU session indication IE is set to a value indicating "a permanent connection PDU session is requested." The method of claim 13 further comprising:

15. In an instance where the result of the determining is to determine that the requested PDU session will not be a permanent PDU session, the method further comprises: Triggering the transmission of a PDU session modification command message, wherein the PDU session modification command message comprises: If the UE includes the Always Connected PDU Session Requested IE in the PDU Session Modification Request message, the Always Connected PDU Session Indication IE is set to a value indicating "Always Connected PDU Session Not Allowed", or If the UE does not include the always-on PDU session requested IE in the PDU session modification request message, the always-on PDU session indication IE is not provided. thing 15. The method of claim 13 or 14, further comprising:

16. When an inter-system change from S1 mode to N1 mode occurs, determining whether the requested PDU session needs to be a permanent PDU session based on the local policy or configuration in the SMF; When determining that the requested PDU session needs to be a permanent PDU session, setting the permanent PDU session indication IE included in the PDU session modification command message to a value indicating "a permanent PDU session is requested", or When determining that the requested PDU session does not need to be a permanent PDU session, setting the permanent PDU session indication IE included in the PDU session modification command message to a value indicating "permanent PDU session is not allowed"; One of them, The method of any one of claims 13 to 15, further comprising:

17. 17. An apparatus comprising at least one processor and at least one memory containing computer program code, the at least one memory and the computer program code being configured, together with the processor, to cause the apparatus to perform a method according to any one of claims 13 to 16.

18. 17. A computer program product, said computer program product comprising at least one non-transitory computer readable storage medium having computer executable program code instructions stored thereon, said computer executable program code instructions comprising program code instructions for performing the method of any one of claims 13 to 16.

19. 1. A method at a UE, comprising: causing transmission of a message comprising a Protocol Data Unit (PDU) Session Modification Request and an Information Element (IE) configured to indicate a request that the PDU session be a permanently connected PDU session, wherein the PDU session is for a Packet Data Network (PDN) connection established in S1 mode, and after an inter-system change from S1 mode to N1 mode, the IE is set to a value indicating a request that the PDU session be a permanently connected PDU session; receiving a PDU Session Modify Command message comprising a permanently connected PDU Session Indication IE in response to the PDU Session Modify Request; In an instance where the Always Connected PDU Session Indication IE is set to a first value, determining that the PDU session will be a Always Connected PDU session; In an instance where the always-on PDU session indication IE is set to a second value, determining that the PDU session does not become a always-on PDU session; A method comprising:

20. In an instance where the always-on PDU session indication IE is included in the PDU session modification command message and the always-on PDU session indication IE is set to a value indicating "a always-on PDU session is requested", the PDU session is considered to be a always-on PDU session.

20. The method of claim 19 further comprising:

21. In an instance where the always-on PDU session indication IE is included in the PDU session modification command message and the always-on PDU session indication IE is set to a value indicating "always-on PDU sessions are not allowed", the PDU session is not considered to be a always-on PDU session.

20. The method of claim 19 further comprising:

22. 20. The method of claim 19, wherein the UE is operating in a single registration mode in a network that supports interworking with N26.

23. 23. An apparatus comprising at least one processor and at least one memory containing computer program code, the at least one memory and the computer program code being configured, together with the processor, to cause the apparatus to perform a method according to any one of claims 19 to 22.

24. 23. A computer program product, said computer program product comprising at least one non-transitory computer readable storage medium having computer executable program code instructions stored thereon, said computer executable program code instructions comprising program code instructions for performing the method of any one of claims 19 to 22.

25. 1. A method comprising: receiving a protocol data unit (PDU) session modification request message from a user equipment (UE), the PDU session modification request message configured to indicate a request for a PDU session for a PDN connection established in S1 mode, receiving the PDU session modification request message after a first inter-system change from S1 mode to N1 mode, the PDU session modification request message may comprise an information element (IE) set to a value indicating a request to make the PDU session a permanent PDU session; Based on a local policy or configuration in a Session Management Function (SMF) and, in instances where the Always Connected PDU Session Required IE is provided, further based on the Always Connected PDU Session Required IE, determine whether the requested PDU session will be a Always Connected PDU session, and communicate the result of the determination to the UE; A method comprising:

26. In an instance where the result of the determining is to determine that the requested PDU session is a constant connection PDU session, causing transmission of a PDU session modification command message, wherein the PDU session modification command message comprises a constant connection PDU session indication IE, and the constant connection PDU session indication IE is set to a value indicating "a constant connection PDU session is requested." 26. The method of claim 25 further comprising:

27. In an instance where the result of the determining is to determine that the requested PDU session will not be a constant connection PDU session, causing transmission of a PDU session modification command message, wherein the PDU session modification command message comprises a constant connection PDU session indication IE if the UE included the constant connection PDU session requested IE in the PDU session modification request message, and does not comprise a constant connection PDU session indication IE if the constant connection PDU session indication IE is set to a value indicating "constant connection PDU session not allowed" or the UE did not include the constant connection PDU session requested IE in the PDU session modification request message.

26. The method of claim 25 further comprising:

28. When an inter-system change from S1 mode to N1 mode occurs, determining whether the requested PDU session needs to be a permanent PDU session based on the local policy or configuration in the SMF; When determining that the requested PDU session needs to be a permanent connection PDU session, setting a permanent connection PDU session indication IE included in the PDU session modification command message to a value indicating "a permanent connection PDU session is requested"; The method of any one of claims 25 to 27, further comprising:

29. When an inter-system change from S1 mode to N1 mode occurs, determining whether the requested PDU session needs to be a permanent PDU session based on the local policy or configuration in the SMF; When determining that the requested PDU session does not need to be a permanent PDU session, setting a permanent PDU session indication IE included in the PDU session modification command message to a value indicating "permanent PDU session is not allowed"; The method of any one of claims 25 to 28, further comprising:

30. 30. An apparatus comprising at least one processor and at least one memory containing computer program code, the at least one memory and the computer program code being configured, together with the processor, to cause the apparatus to perform a method according to any one of claims 25 to 29.

31. 30. A computer program product, said computer program product comprising at least one non-transitory computer readable storage medium having computer executable program code instructions stored thereon, said computer executable program code instructions comprising program code instructions for performing the method of any one of claims 25 to 29.

32. 1. A method performed via a user equipment (UE), the method comprising: Include in a Protocol Data Unit (PDU) Session Modification Request message an information element (IE) configured to indicate a request that the PDU session be a permanent PDU session, the PDU session being for a packet data network (PDN) connection established during S1 mode, and the Session Modification Request message being sent after a first inter-system change from S1 mode to N1 mode; Setting the IE in the PDU session modification request message to a value indicating the request that the PDU session be a permanent PDU session; Triggering the transmission of the PDU Session Modification Request message; Receiving a PDU Session Modify Command message including a Always Connected PDU Session Indication IE, wherein the Always Connected PDU Session Indication IE is set to a value indicating "a Always Connected PDU Session is requested" or a value indicating "a Always Connected PDU Session is not allowed"; A method comprising:

33. In an instance where the always-on PDU session indication IE is included in the PDU session modification command message and the always-on PDU session indication IE is set to a value indicating "a always-on PDU session is requested", the PDU session is considered to be a always-on PDU session.

33. The method of claim 32, further comprising:

34. In an instance where the always-on PDU session indication IE is included in the PDU session modification command message and the always-on PDU session indication IE is set to a value indicating "always-on PDU sessions are not allowed", the PDU session is not considered to be a always-on PDU session.

33. The method of claim 32, further comprising:

35. 33. The method of claim 32, wherein the UE is operating in a single registration mode in a network that supports interworking with N26.

36. 36. An apparatus comprising at least one processor and at least one memory containing computer program code, the at least one memory and the computer program code being configured, together with the processor, to cause the apparatus to perform a method according to any one of claims 32 to 35.

37. 36. A computer program product, said computer program product comprising at least one non-transitory computer readable storage medium having computer executable program code instructions stored thereon, said computer executable program code instructions comprising program code instructions for performing the method of any one of claims 32 to 35.

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