Method and apparatus for providing always-on attributes of a PDU session and for providing interworking aspects with respect to always-on PDU sessions - Patents.com

Abstract

To provide a method and apparatus for establishing always-on as an attribute of a protocol data unit (PDU) session.SOLUTION: An example method may include receiving, from UE, a PDU session establishment request message by a session management function (SMF), the PDU session establishment request message comprising an always-on PDU session requested information element (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, cause transmission of 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 requested ("Always-on PDU session requested").SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] Exemplary embodiments relate generally to methods and apparatus for providing always-on connectivity as an attribute of a protocol data unit (PDU) session and for providing interworking aspects with respect to always-on PDU sessions, and more specifically, to methods and apparatus for providing functionality that enables a network to determine whether a PDU session can be made into an always-on PDU session. [Background technology]

[0002] In fifth generation wireless systems (5G), a user equipment (UE) cannot initiate a service request procedure while another service request procedure is in progress, i.e. a new service request procedure can only be initiated if an old service request procedure is completed. This restriction may cause delays to services that use PDU sessions that are requested to be reactivated in the new service request procedure.

[0003] Since such delays can be problematic for delay-sensitive services, "always-on PDU sessions" were introduced. An always-on PDU session is a PDU session that requires user plane resources to be activated during the transition from 5GMM-IDLE to 5GMM-CONNECTED mode. Such a PDU session may be established based on an indication from higher layers. However, the current specification (i.e., 3GPP TS 24.501) does not provide any indication as to how higher layers in the UE can be configured to provide the indication.

[0004] Therefore, network control is missing from always-on PDU sessions. In particular, the network does not know whether a PDU session is an always-on PDU session, and the network cannot set the PDU session to an always-on PDU session or an uninterrupted PDU session. Because an always-on PDU session may consume more network resources than an uninterrupted PDU session, this application proposes a solution to introduce network control of an always-on PDU session. Summary of the Invention

[0005] In the current specification, the "always-on" property is not considered an attribute of a PDU session. Examples of existing PDU session attributes are SSC mode, PDU session type, DNN, and S-NSSAI. There is a need to maximize commonality between these attributes. More specifically, the UE must be able to indicate to the network via the PDU Session Establishment Request message whether it requests the PDU session to be always-on or not, since this can minimize the number of user subscription checks to determine the always-on property. That is, if the always-on property is not requested and the DNN is the Internet, the SMF can be configured to determine the PDU session as an always-on PDU session without checking the user's subscription. However, it should not be misconstrued that the network can decide to make a PDU session always-on. The always-on decision may be made only if the UE requests it. However, it is up to the network to decide whether a PDU session can be an always-on PDU session or not. Since always-on PDU sessions may require session continuity during inter-system changes, it is necessary to specify interworking aspects. These interworking aspects are missing in the current specification.

[0006] According to exemplary embodiments, methods, apparatus, and computer program products are provided for providing and / or utilizing always-on connectivity as an attribute of a Protocol Data Unit (PDU) session and for providing interworking aspects with respect to always-on PDU sessions. Additionally, methods, apparatus, and computer program products are provided for providing functionality that allows a network to determine whether a PDU session can be an always-on PDU session.

[0007] In some embodiments, a method for performing a service request procedure may be provided, the method including 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 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 does not comprise the Always-On PDU Session Requested IE, and determining whether the requested PDU session shall be established as an Always-On PDU session based on a local policy or configuration and, in instances where the Always-On PDU Session Requested IE is available, the Always-On PDU Session Requested IE.

[0008] In some embodiments, the method may further include causing transmission of a PDU session establishment acknowledgement message upon determining that the requested PDU session is to be established as an always-on PDU session, the PDU session establishment acknowledgement message comprising an always-on PDU session indication IE, the always-on PDU session indication IE being set to a value indicating "always-on PDU session is requested."

[0009] In some embodiments, the method may further comprise causing transmission of a PDU session establishment acknowledgement message upon determining that the requested PDU session is not to be established as an always-on PDU session, the PDU session establishment acknowledgement message comprising an always-on PDU session indication IE, where the always-on PDU session indication IE is set to a value indicating "always-on PDU session is not allowed" if the UE included the always-on PDU session requested IE in the PDU session establishment request message, or does not comprise the 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.

[0010] In some embodiments, in an instance where an 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 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 acknowledgement message, or 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 allowed", the method further comprises causing the UE to not consider the established PDU session as an always-on PDU session.

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

[0013] In some embodiments, the method may further include determining, upon an inter-system change from the S1 mode to the N1 mode, 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.

[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, together with the processor, configured to cause the apparatus to at least: receive 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 new PDU session, the PDU session establishment request message comprising an Always-On PDU Session Requested Information Element (IE), where the Always-On PDU Session Requested IE is set to a value indicating a request to establish a new Always-On PDU session, or the PDU session establishment request message does not comprise the Always-On PDU Session Requested IE, and determine whether the requested PDU session shall be established as an Always-On PDU session based on a local policy or configuration and, in instances where the Always-On PDU Session Requested IE is available, the Always-On PDU Session Requested IE.

[0015] In some embodiments, the at least one memory and computer program code, together with the processor, are further configured to cause the device to cause, upon determining that the requested PDU session is to be established as an always-on PDU session, to send a PDU session establishment acknowledgement message, the PDU session establishment acknowledgement message comprising an always-on PDU session indication IE, the always-on PDU session indication IE being set to a value indicating "an always-on PDU session is requested."

[0016] In some embodiments, the at least one memory and computer program code, together with the processor, are further configured to cause the device to cause transmission of a PDU session establishment acknowledgement message when it determines that the requested PDU session is not to be established as an always-on PDU session, the PDU session establishment acknowledgement message comprising an always-on PDU session indication IE, the always-on PDU session indication IE being set to a value indicating "always-on PDU session is not allowed" if the UE included the always-on PDU session requested IE in the PDU session establishment request message, or not comprising the 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.

[0017] In some embodiments, 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 at least one memory and computer program code, together with the processor, are further configured to cause the device to cause the UE to consider the established PDU session as an always-on PDU session.

[0018] In some embodiments, in an instance where the always-on PDU session indication IE is not included in the PDU session establishment acknowledgement message or 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 allowed," the at least one memory and computer program code, together with the processor, are further configured to cause the device to cause the UE not to consider the established PDU session as an always-on PDU session.

[0019] In some embodiments, the at least one memory and computer program code, together with the processor, are further configured to cause the apparatus to maintain an always-on PDU session indication at the UE and the SMF upon an inter-system change from the N1 mode to the S1 mode.

[0020] In some embodiments, the at least one memory and computer program code, together with the processor, are further configured to cause the device to determine, upon an inter-system change from the S1 mode to the N1 mode, 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.

[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 having stored thereon computer-executable program code instructions for 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 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 does not comprise the Always-On PDU Session Requested IE, and determining whether the requested PDU session shall be established as an Always-On PDU session based on local policies and configurations and, in instances where the Always-On PDU Session Requested IE is available, the Always-On PDU Session Requested IE.

[0022] In some embodiments, the computer-executable program code instructions further comprise program code instructions that, upon determining that the requested PDU session is to be established as an always-on PDU session, cause transmission of a PDU session establishment acknowledgement message, the PDU session establishment acknowledgement message comprising an always-on PDU session indication IE, and the always-on PDU session indication IE is set to a value indicating "an always-on PDU session is requested."

[0023] In some embodiments, the computer-executable program code instructions further comprise program code instructions that, upon determining that the requested PDU session is not to be established as an always-on PDU session, cause transmission of a PDU session establishment acknowledgement message, the PDU session establishment acknowledgement message comprising an always-on PDU session indication IE, which is set to a value indicating "always-on PDU session is not allowed" if the UE included the always-on PDU session requested IE in the PDU session establishment request message, or does not comprise the 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.

[0024] In some embodiments, 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 computer-executable program code instructions further comprise program code instructions for causing the UE to consider the established PDU session as an always-on PDU session.

[0025] In some embodiments, in an instance where the always-on PDU session indication IE is not included in the PDU session establishment acknowledgement message or 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 allowed," the computer-executable program code instructions further comprise program code instructions for causing the UE to not consider 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 an always on PDU session indication in the UE and the SMF upon an inter-system change from the N1 mode to the S1 mode.

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

[0028] In some embodiments, an apparatus for performing a service request procedure may be provided, the apparatus comprising: means for 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 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 does not comprise the Always-On PDU Session Requested IE; and means for determining whether the requested PDU session shall be established as an Always-On PDU session based on a local policy or configuration and, in instances where the Always-On PDU Session Requested IE is available, the Always-On PDU Session Requested IE.

[0029] In some embodiments, the apparatus may further comprise means for causing transmission of a PDU session establishment acknowledgement message upon determining that the requested PDU session is to be established as an always-on PDU session, the PDU session establishment acknowledgement message comprising an always-on PDU session indication IE, the always-on PDU session indication IE being set to a value indicating "always-on PDU session is requested."

[0030] In some embodiments, the apparatus may further comprise means for causing transmission of a PDU session establishment acknowledgement message upon determining that the requested PDU session is not to be established as an always-on PDU session, the PDU session establishment acknowledgement message comprising an always-on PDU session indication IE, the always-on PDU session indication IE being set to a value indicating "always-on PDU session is not allowed" if the UE included the always-on PDU session requested IE in the PDU session, or not comprising the 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.

[0031] In some embodiments, in an instance where an 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 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 acknowledgement message, or 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 allowed", the apparatus further comprises means for causing the UE to not consider the established PDU session as an always-on PDU session.

[0033] In some embodiments, the apparatus may further comprise means for maintaining an always-on PDU session indication at the UE and the SMF upon an inter-system change from the N1 mode to the S1 mode.

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

[0035] In some embodiments, the method further comprises: causing transmission of a protocol data unit (PDU) session establishment request message, the PDU session establishment request message 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) set to a value indicating a request to establish a new always-on PDU session, or the PDU session establishment request message does not comprise an always-on PDU session requested IE; and upon determining that the requested PDU session is to be established as an always-on PDU session, receiving a PDU session establishment acknowledgement message, the PDU session establishment acknowledgement message comprising an always-on PDU session indication. In one embodiment, the method comprises: receiving a PDU session establishment request message, the PDU session establishment request message including an always-on PDU session indication IE, and the always-on PDU session indication IE is set to a value indicating "always-on PDU session is requested", and if it is determined that the requested PDU session cannot be established as an always-on PDU session, receiving a PDU session establishment acknowledgement message, the PDU session establishment acknowledgement message including an always-on PDU session indication IE, and the always-on PDU session indication IE is set to a value indicating "always-on PDU session is not allowed" if the UE has included the always-on PDU session requested IE in the PDU session establishment request message, and not including the always-on PDU session indication IE if the UE has not included the always-on PDU session requested IE in the PDU session establishment request message.

[0036] In some embodiments, the method may further comprise considering the established PDU session as an always-on PDU session in an instance where an 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."

[0037] In some embodiments, the method may further comprise not considering the established PDU session as an always-on PDU session in an instance where an 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 allowed."

[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, together with the processor, for causing transmission of a protocol data unit (PDU) session establishment request message, the PDU session establishment request message 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) 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 does not comprise the always-on PDU session requested IE, and receiving a PDU session establishment acknowledgement message upon determining that the requested PDU session is to be established as an always-on PDU session. The device is configured to at least cause the device to perform the following: receiving a PDU session establishment acknowledgement message, wherein the PDU session establishment acknowledgement message comprises an always-on PDU session indication IE, and the always-on PDU session indication IE is set to a value indicating "an always-on PDU session is requested", and if it is determined that the requested PDU session should not be established as an always-on PDU session, receiving a PDU session establishment acknowledgement message, wherein the PDU session establishment acknowledgement message comprises an always-on PDU session indication IE, and the always-on PDU session indication IE is set to a value indicating "a always-on PDU session is not allowed" if the UE has included the always-on PDU session requested IE in the PDU session establishment request message, or does not comprise the always-on PDU session indication IE if the UE has not included the always-on PDU session requested IE in the PDU session establishment request message.

[0039] In some embodiments, the at least one memory and computer program code, together with the processor, are further configured to cause the device to consider the established PDU session as an always-on PDU session in an instance where an 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."

[0040] In some embodiments, the at least one memory and computer program code, together with the processor, are further configured to cause the device to not consider the established PDU session as an always-on PDU session in an instance where an 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 allowed."

[0041] In some embodiments, a computer program product may be provided that comprises at least one non-transitory computer-readable storage medium having computer-executable program code instructions stored thereon, the computer-executable program code instructions being configured 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 an always-on PDU session requested 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 the always-on PDU session requested IE; and upon determining that the requested PDU session is to be established as an always-on PDU session, cause transmission of a PDU session establishment acknowledgement message. The method comprises: receiving a PDU session establishment acknowledgement message, the PDU session establishment acknowledgement message comprising an always-on PDU session indication IE, the always-on PDU session indication IE being set to a value indicating "an always-on PDU session is requested", and if it is determined that the requested PDU session should not be established as an always-on PDU session, receiving a PDU session establishment acknowledgement message, the PDU session establishment acknowledgement message comprising an always-on PDU session indication IE, the always-on PDU session indication IE being set to a value indicating "a always-on PDU session is not allowed" if the UE has included an always-on PDU session requested IE in the PDU session establishment request message, or not comprising an always-on PDU session indication IE if the UE has not included an always-on PDU session requested IE in the PDU session establishment request message.

[0042] In some embodiments, the computer-executable program code instructions further comprise program code instructions for considering the established PDU session as an always-on PDU session in an instance where an 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."

[0043] In some embodiments, the computer-executable program code instructions further comprise program code instructions for not considering the established PDU session as an always-on PDU session in an instance where an 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 allowed."

[0044] In some embodiments, means for causing transmission of a protocol data unit (PDU) session establishment request message, the PDU session establishment request message 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) set to a value indicating a request to establish a new always-on PDU session, or the PDU session establishment request message does not comprise an always-on PDU session requested IE; and means for receiving a PDU session establishment acknowledgement message upon determining that the requested PDU session is to be established as an always-on PDU session, the PDU session establishment acknowledgement message comprising an always-on PDU session indication IE set to a value indicating a request to establish a new always-on PDU session. An apparatus may be provided comprising: a receiving means for receiving a PDU session establishment acknowledgement message when it is determined that the requested PDU session is not to be established as an always-on PDU session, the PDU session establishment acknowledgement message comprising the always-on PDU session indication IE and the always-on PDU session indication IE being set to a value indicating "always-on PDU session is requested", the always-on PDU session indication IE being set to a value indicating "always-on PDU session is not allowed" if the UE has included the always-on PDU session requested IE in the PDU session establishment request message, or not comprising the always-on PDU session indication IE if the UE has not included the always-on PDU session requested IE in the PDU session establishment request message.

[0045] In some embodiments, the device may further comprise means for considering the established PDU session as an always-on PDU session in an instance where an 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."

[0046] In some embodiments, the device may further comprise means for not considering the established PDU session as an always-on PDU session in an instance where an 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 allowed."

[0047] In some embodiments, a method may be provided that comprises receiving, from a user equipment (UE), a protocol data unit (PDU) session modification request message configured to indicate a request to modify a PDU session corresponding to a PDN connection established during S1 mode after an initial inter-system change from S1 mode to N1 mode, where the PDU session modification request message comprises 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 whether to make the requested PDU session an always-on PDU session based on a local policy or configuration.

[0048] In some embodiments, upon determining that the requested PDU session is an always-on PDU session, the method further comprises causing transmission of a PDU session modify command message, the PDU session modify command message comprising an always-on PDU session indication IE, the always-on PDU session indication IE being set to a value indicating "always-on PDU session is requested."

[0049] In some embodiments, upon determining that the requested PDU session is not to be an always-on PDU session, the method further comprises causing transmission of a PDU session modify command message, the PDU session modify command message comprising an always-on PDU session indication IE, the always-on PDU session indication IE being set to a value indicating "always-on PDU session is not allowed."

[0050] In some embodiments, in an instance where an 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 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 an 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 is not allowed", the method further comprises causing the UE to not consider the PDU session as an always-on PDU session.

[0052] In some embodiments, during an inter-system change from S1 mode to N1 mode, based on a local policy or configuration of the SMF, it is determined whether the requested PDU session needs to be a permanent PDU session, and if it is determined that the requested PDU session needs to be a permanent PDU session, the permanent PDU session indication IE included in the PDU session modification command message is set to a value indicating "permanent PDU session is requested."

[0053] In some embodiments, the method may further include, upon an inter-system change from S1 mode to N1 mode, determining based on a local policy or configuration of the SMF whether the requested PDU session needs to be an always-on PDU session, and, upon determining that the requested PDU session does not need to be an always-on PDU session, setting an always-on PDU session indication IE included in the PDU session modify command message to a value indicating "always-on PDU session is not allowed."

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

[0055] In some embodiments, the at least one memory and computer program code, together with the processor, are further configured to cause the device to send a PDU session modify command message upon determining that the requested PDU session is to be an always-on PDU session, the PDU session modify command message comprising an always-on PDU session indication IE, the always-on PDU session indication IE being set to a value indicating "always-on PDU session is requested."

[0056] In some embodiments, the at least one memory and computer program code, together with the processor, are further configured to cause the device to send a PDU session modify command message upon determining that the requested PDU session is not to be an always-on PDU session, the PDU session modify command message comprising an always-on PDU session indication IE, the always-on PDU session indication IE being set to a value indicating "always-on PDU session is not allowed."

[0057] In some embodiments, the at least one memory and computer program code, together with the processor, are further configured to cause the device to cause the UE to 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 and the always-on PDU session indication IE is set to a value indicating "always-on PDU session is requested."

[0058] In some embodiments, the at least one memory and computer program code, together with the processor, are further configured to cause the device to cause the UE to not consider the PDU session as an always-on PDU session in an instance where an 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 is not allowed."

[0059] In some embodiments, the at least one memory and computer program code, together with the processor, are further configured to cause the device to determine, upon an inter-system change from S1 mode to N1 mode, whether the requested PDU session needs to be an always-on PDU session based on a local policy or configuration of the SMF, and, upon determining that the requested PDU session needs to be an always-on PDU session, set an always-on PDU session indication IE included in the PDU session modification command message to a value indicating "always-on PDU session is requested."

[0060] In some embodiments, the at least one memory and computer program code, together with the processor, are further configured to cause the device to determine, upon an inter-system change from S1 mode to N1 mode, whether the requested PDU session needs to be an always-on PDU session based on a 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 an always-on PDU session indication IE included in the PDU session modification command message to a value indicating "always-on PDU session is not allowed."

[0061] In some embodiments, a computer program product may be provided comprising at least one non-transitory computer-readable storage medium having computer-executable program code instructions stored thereon, the computer-executable program code instructions including program code instructions for 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 to modify a PDU session corresponding to a PDN connection established during an S1 mode after an initial inter-system change from the S1 mode to an 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 whether the requested PDU session should be made an always-on PDU session based on a local policy or configuration.

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

[0063] In some embodiments, upon determining that the requested PDU session is not to be an always-on PDU session, the computer-executable program code instructions further comprise program code instructions that cause transmission of a PDU session modify command message, the PDU session modify command message comprising an always-on PDU session indication IE, and the always-on PDU session indication IE is set to a value indicating "always-on PDU session is not allowed."

[0064] In some embodiments, in an instance where the Always-On PDU Session Indication IE is included in the PDU Session Modify 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 an 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 is not allowed," the computer-executable program code instructions further comprise program code instructions that cause the UE to not consider the PDU session as an always-on PDU session.

[0066] In some embodiments, the computer-executable program code instructions further comprise program code instructions for determining, upon an inter-system change from S1 mode to N1 mode, whether the requested PDU session needs to be an always-on PDU session based on a local policy or configuration of the SMF, and, upon determining that the requested PDU session needs to be an always-on PDU session, setting an always-on PDU session indication IE included in the PDU session modify command message to a value indicating "always-on PDU session is requested."

[0067] In some embodiments, the computer-executable program code instructions further comprise program code instructions for determining, upon an inter-system change from S1 mode to N1 mode, whether the requested PDU session needs to be an always-on PDU session based on a 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, setting an always-on PDU session indication IE included in the PDU session modify command message to a value indicating "always-on PDU session is not allowed."

[0068] In some embodiments, an apparatus may be provided that includes means for receiving, from a user equipment (UE), a protocol data unit (PDU) session modification request message, where the PDU session modification request message is configured to indicate a request to modify a PDU session corresponding to a PDN connection established during S1 mode after an initial inter-system change from S1 mode to N1 mode, where the PDU session modification request message includes 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 a 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, upon determining that the requested PDU session is to be an always-on PDU session, causing transmission of a PDU session modify command message, the PDU session modify command message comprising an always-on PDU session indication IE, the always-on PDU session indication IE being set to a value indicating "always-on PDU session is requested."

[0070] In some embodiments, the device may further include means for causing transmission of a PDU session modify command message upon determining that the requested PDU session is not to be an always-on PDU session, the PDU session modify command message including an always-on PDU session indication IE, the always-on PDU session indication IE being set to a value indicating "always-on PDU session is not allowed."

[0071] In some embodiments, in an instance where the Always-On PDU Session Indication IE is included in the PDU Session Modify Command message and the Always-On PDU Session Indication IE is set to a value indicating "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 Modify Command message and the Always-On PDU Session Indication IE is set to a value indicating "Always-On PDU Session is not allowed", the apparatus further comprises means for causing the UE to not consider the PDU session as an Always-On PDU session.

[0073] In some embodiments, the device may further include means for determining, upon an inter-system change from S1 mode to N1 mode, whether the requested PDU session needs to be a permanent PDU session based on a local policy or configuration of the SMF, and means for setting a permanent PDU session indication IE included in the PDU session modification command message to a value indicating "permanent PDU session is requested" upon determining that the requested PDU session needs to be a permanent PDU session.

[0074] In some embodiments, the device may further include means for determining, upon an inter-system change from S1 mode to N1 mode, whether the requested PDU session needs to be an always-on PDU session based on a local policy or configuration of the SMF, and means for setting an always-on PDU session indication IE included in the PDU session modification command message to a value indicating "always-on PDU session is not allowed" if it is determined that the requested PDU session does not need to be an always-on PDU session.

[0075] In some embodiments, the method includes causing transmission of a protocol data unit (PDU) session modification request message, the PDU session modification request message configured to indicate a request to modify a PDU session corresponding to a PDN connection established during an S1 mode after an initial intersystem 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; and upon determining that the requested PDU session is an always-on PDU session, causing transmission of a PDU session modification command message. A method may be provided that includes receiving a PDU session modify command message, where the PDU session modify command message comprises an always-on PDU session indication IE, and the always-on PDU session indication IE is set to a value indicating "always-on PDU session is requested", and upon determining that the requested PDU session should not be an always-on PDU session, receiving a PDU session modify command message, where the PDU session modify command message comprises an always-on PDU session indication IE, and the always-on PDU session indication IE is set to a value indicating "always-on PDU session is not allowed".

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

[0077] In some embodiments, the method may further comprise not considering the 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 modify command message and the always-on PDU session indication IE is set to a value indicating "always-on PDU session is not allowed."

[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, together with the processor, for causing transmission of a protocol data unit (PDU) session modification request message, the PDU session modification request message configured to indicate a request to modify a PDU session corresponding to a PDN connection established during an S1 mode after an initial inter-system change from the S1 mode to an 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, The device is configured to at least cause the device to perform the following steps when it is determined that the requested PDU session is to be an always-on PDU session: receive a PDU session modify command message, the PDU session modify command message having 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 requested"; and when it is determined that the requested PDU session is not to be an always-on PDU session, receive a PDU session modify command message, the PDU session modify command message having 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 allowed."

[0079] In some embodiments, the at least one memory and computer program code, together with the processor, are further configured to cause the device to consider the PDU session as an always-on PDU session in an instance where an 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 is requested."

[0080] In some embodiments, the at least one memory and computer program code, together with the processor, are further configured to cause the device to not consider the PDU session as an always-on PDU session in an instance where an 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 is not allowed."

[0081] In some embodiments, a computer program product may be provided that comprises at least one non-transitory computer-readable storage medium having computer-executable program code instructions stored thereon, the computer-executable program code instructions including: causing transmission of a protocol data unit (PDU) session modification request message, the PDU session modification request message configured to indicate a request to modify a PDU session corresponding to a PDN connection established during an S1 mode after an initial inter-system change from the S1 mode to an 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 transmitting the requested PDU session modification request message. The method comprises program code instructions for receiving, when it is determined that the PDU session is to be an always-on PDU session, a modify PDU session command message, the PDU session modify command 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", and receiving, when it is determined that the requested PDU session is not to be an always-on PDU session, a modify PDU session command message, the PDU session modify command 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 not allowed".

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

[0083] In some embodiments, the computer-executable program code instructions further comprise program code instructions for not considering the PDU session as an always-on PDU session in an instance where an 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 is not allowed."

[0084] In some embodiments, the method includes: causing transmission of a protocol data unit (PDU) session modification request message, the PDU session modification request message configured to indicate a request to modify a PDU session corresponding to a PDN connection established during an S1 mode after an initial 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; and upon determining that the requested PDU session is an always-on PDU session, sending a PDU session modification command message. An apparatus may be provided that includes: means for receiving a PDU session modify command message, where the PDU session modify command message includes an always-on PDU session indication IE, and the always-on PDU session indication IE is set to a value indicating "always-on PDU session is requested", and means for receiving a PDU session modify command message if it is determined that the requested PDU session should not be an always-on PDU session, where the PDU session modify command message includes an always-on PDU session indication IE, and the always-on PDU session indication IE is set to a value indicating "always-on PDU session is not allowed".

[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 an 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 is requested."

[0086] In some embodiments, the device may further comprise means for not considering the 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 "always-on PDU session is not allowed."

[0087] Having thus described in general terms various embodiments of the present disclosure, reference will now be made to the accompanying drawings, which are not necessarily to scale. [Brief description of the drawings]

[0088] [Figure 1A] FIG. 1 is a block diagram of a system that may be specifically configured in accordance with an exemplary embodiment of the present disclosure. [Figure 1B] FIG. 1 is a block diagram of a system that may be specifically configured in accordance with an exemplary embodiment of the present disclosure. [Diagram 2] FIG. 2 is a block diagram of an apparatus that may be specifically configured according to an exemplary embodiment of the present disclosure. [Diagram 3] FIG. 2 is a data flow diagram illustrating an exemplary embodiment of the present invention. [Figure 4] 3 is a flow chart illustrating operations performed by an apparatus such as that of FIG. 2, according to an exemplary embodiment of the present disclosure. [Diagram 5] 3 is a flow chart illustrating operations performed by an apparatus such as that of FIG. 2, according to an exemplary embodiment of the present disclosure. [Figure 6] FIG. 2 is a data flow diagram illustrating an exemplary embodiment of the present invention. [Figure 7] 3 is a flow chart illustrating operations performed by an apparatus such as that of FIG. 2, according to an exemplary embodiment of the present disclosure. [Figure 8] 3 is a flow chart illustrating operations performed by an apparatus such as that of FIG. 2, according to an exemplary embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0089] Some embodiments of the present invention are described in further detail below with reference to the accompanying drawings. The following description presents some, but not all, of the present invention. Indeed, various embodiments of the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth 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 may be transmitted, received, and / or stored by embodiments of the present invention. Thus, use of such terms should not be considered as limiting the spirit and scope of embodiments of the present invention.

[0090] Additionally, as used herein, the term "circuit" refers to (a) a hardware-only circuit implementation (e.g., an implementation in analog and / or digital circuitry), (b) a combination of a circuit and a computer program product(s) including software and / or firmware instructions stored in one or more computer-readable memories that work together to cause an apparatus to perform one or more functions described herein, and (c) a circuit that requires software or firmware for operation even when the software or firmware is not physically present, e.g., a microprocessor(s) or a portion of a microprocessor(s). This definition of "circuit" applies to all uses of the term herein, including the claims. As a further example, as used herein, the term "circuit" also includes implementations that include one or more processors and / or portion(s) thereof, and associated software and / or firmware. As another example, the term "circuit" as used herein also includes, for example, baseband or application processor integrated circuits for mobile phones, or similar integrated circuits for servers, cellular network devices, other network devices, field programmable gate arrays, and / or other computing devices.

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

[0092] Methods, apparatus, and computer program products may be provided for providing always-on connectivity as an attribute of a PDU session. Methods, apparatus, and computer program products may also be provided for providing interworking aspects with respect to always-on PDU sessions. Methods, apparatus, and computer program products may also be provided for providing functionality that allows a network to determine whether a PDU session may be an always-on PDU session.

[0093] 1, an exemplary system is shown supporting communication between multiple stations 10 and one or more wireless base stations / access points 12 (e.g., a high density system scenario in which multiple wireless base stations / access points may be deployed in a geographic area and may operate on the same frequency channel), with each wireless base station / access point communicating with one or more stations, and in one embodiment, with multiple stations. The wireless base stations / access points may then communicate with a network 14. The wireless base stations / access points may communicate via a 5G, Long Term Evolution (LTE), or LTE Advanced (LTE-A) network, although other networks may support communication between the access points. Other networks include networks configured according to Wideband Code Division Multiple Access (W-CDMA), CDMA2000, Global System for Mobile Communications (GSM), General Packet Radio System (GPRS), IEEE 802.11 standards, including amendments to the IEEE 802.11ah or 802.11ac standards or other newer standards, Wireless Local Access Networks (WLANs), Worldwide Interoperability for Microwave Access (WiMAX) protocols, Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Networks (UTRANs), and the like, as well as other standards for multi-domain networks, which may include industrial wireless communication networks, such as WirelessHART, Bluetooth, ZigBee, and the like.

[0094] The wireless base station / access point 12 and the station 10 may communicate via wired communication, but most commonly, via wireless communication. For example, the wireless base station / access point and the station may communicate in the sub-1 GHz band as defined in the IEEE 802.11ah standard, or in the 5 GHz band as may be defined in the IEEE 802.11ac standard. The wireless base station / access point may be embodied by any of a variety of 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 any number of other handheld or portable communication devices, computing devices, content generation devices, content consumption devices, or combinations thereof). The station may also be embodied by a variety of devices, such as a sensor, a meter, etc. The sensors and meters may be deployed in a variety of different applications including utility applications serving 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. A station embodied by the sensor or meter may be utilized in some embodiments to backhaul the sensor and meter data. Alternatively, the station may be embodied by a mobile terminal or user equipment (UE), such as, for example, a mobile communication device, such as a mobile phone, a smart phone, a portable digital assistant (PDA), a pager, a laptop computer, a tablet computer, or any of a number of other handheld or portable communication devices, computing devices, content generation devices, content consumption devices, or combinations thereof.In embodiments in which the station is embodied by a mobile terminal, communication between the access point and the station may serve to extend the range of a Wi-Fi or other wireless local area network (WLAN), e.g., by extending the range of a hotspot, and may serve to offload traffic that would otherwise be carried by a cellular or other network.

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

[0096] FIG. 1B illustrates the principles of 5G architecture in the current draft 3GPP specification. In particular, FIG. 1B is a networked system 100 according to an exemplary embodiment of the present disclosure. FIG. 1B specifically illustrates a user equipment (UE) 102 that may communicate with a radio access network (RAN) 104, an access and mobility management function (AMF) 108, and a user plane function (UPF) 106. The AMF 108 may then 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 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 embodying any of the network devices, including but not limited to the radio base station / access point 12 and / or station 10, UE 102, SMF 110, or any of the other devices shown in the figures, the radio base station / access point 12 and / or station 10, UE 102, or any of the other devices shown may include or be associated with an apparatus 20, as shown in Figure 2. In this regard, the apparatus may include or be in communication with a processor 22, a memory device 24, and a communication interface 26. Thus, while in some embodiments devices or elements are shown as being in communication with one another, hereinafter it should be considered that such devices or elements may be embodied within the same device or element, and thus devices or elements shown as being in communication should alternatively be understood to be part of the same device or element.

[0098] In some embodiments, the processor 22 (and / or any other processing circuitry that assists or is associated with the processor) may communicate with the memory device 24 via a bus for conveying information between 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) that includes gates configured to store data (e.g., bits) that may be searchable 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 device 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, the 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 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., baseboard). The structural assembly may provide physical strength, size conservation, and / or electrical interaction limitations of the component circuits contained 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-chip." Thus, in some cases, the chip or chipset may constitute a means for performing one or more operations to provide the functionality described herein.

[0100] The processor 22 may be embodied in a number of different ways. For example, the processor may be embodied as one or more of a variety of hardware processing means, such as a co-processor, a microprocessor, a controller, a digital signal processor (DSP), a processing element with or without an associated DSP, or various other processing circuits, including integrated circuits, such as, for example, an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), 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 multiple threads.

[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 hardware or software methods, or a combination thereof, the processor may represent an entity (e.g., physically embodied in circuitry) that can perform operations according to embodiments of the present invention, while being configured accordingly. Thus, for example, if the processor is embodied as an ASIC, FPGA, etc., the processor may be hardware that is specifically configured to perform the operations described herein. Alternatively, 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 that is configured to employ embodiments of the present invention, upon further configuration of the processor by the instructions to perform 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] Meanwhile, 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 multiple antennas) and supporting hardware and / or software for enabling wireless communication. Additionally or alternatively, the communication interface may include circuitry for interacting with the antenna(s) to transmit signals via the antenna(s) or for processing 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 technology. 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 for supporting communication via 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 illustrates a data flow diagram illustrating an exemplary embodiment of the present invention. In particular, FIG. 3 illustrates the initiation of a UE-initiated PDU session establishment procedure followed by an SMF response. For example, in some embodiments, the UE may initiate a UE-requested PDU session establishment procedure. If the UE requests the establishment of a new always-on PDU session, the UE may include an always-on PDU session requested information element (IE) and set the value of the IE to "always-on PDU session requested", etc. Thus, as shown at 305, the UE 102 may provide a PDU session establishment request message to the SMF 110. Then, also at 305, the SMF 110 receives a PDU session establishment request message from the UE 102. The PDU session establishment request message may include an always-on PDU session requested IE, and the always-on PDU session requested IE is set to a value such as "always-on PDU session requested".

[0104] Following receipt of the Always-On PDU Session Requested IE in the PDU Session Establishment Request message set to a value such as "Always-On PDU Session is Requested", the determination may be made, for example, based on a local policy or configuration of the SMF. That is, as shown in step 310 of FIG. 3, following receipt of the PDU Session Establishment Request message from the UE, the SMF may provide a PDU Session Establishment Accept 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 shall include an Always-On PDU Session Indication IE in the PDU Session Establishment Accept message and set the value to "Always-On PDU Session is Requested". In some embodiments, for example, if the SMF determines that the requested PDU session shall not be established as an Always-On PDU session and the UE includes an Always-On PDU Session Requested IE, the SMF shall include an Always-On PDU Session Indication IE in the PDU Session Establishment Accept message and set the value to "Always-On PDU Session is not allowed". In some embodiments, for example, if the SMF determines that the requested PDU session should not be established as an always-on PDU session and the UE has not included an always-on PDU session requested IE, the SMF does not include an always-on PDU session indication IE in the PDU session establishment acknowledgement message.

[0105] Thereafter, if the Always-On PDU Session Indication IE is included in the PDU Session Establishment Acknowledge message and its value is set to "Always-On PDU Session 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 Acknowledge message but its value is set to "Always-On PDU Session Not Allowed", 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 Acknowledge message, it shall not consider the established PDU session as an Always-On PDU Session.

[0106] For an inter-system change from N1 mode to S1 mode, after an 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., an inter-system change from S1 mode to N1 mode), the UE and the SMF may use the always-on PDU session indication to determine whether the PDU session forwarded from the EPS is a always-on PDU session.

[0107] Regarding inter-system change from S1 mode to N1 mode, when inter-system change 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 that is maintained in the UE.

[0108] 5 and 6 illustrate operations performed by, for example, an apparatus embodied by an SMF and a UE, respectively, for example, to utilize a PDU session establishment procedure, in particular to provide and / or utilize an always-on connection as an attribute of a PDU session, and to provide interworking aspects with respect to an always-on PDU session. That is, in another exemplary embodiment, a method, apparatus, and / or computer program product may be provided for providing a procedure for establishing a PDU session, in particular to utilize an always-on connection as an attribute of a PDU session to determine whether to provide an always-on PDU session, and to provide an always-on PDU session upon determining to provide an always-on PDU session. FIG. 5 is an exemplary flow chart illustrating a method of operating an exemplary apparatus, for example apparatus 200, embodied by, for example, an SMF 110, performed according to an embodiment of the present invention.

[0109] In an exemplary embodiment, the apparatus 20 includes means, such as the processor 210, configured to receive a PDU session establishment request message from the UE. 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 PDU session. See block 405 of FIG. 4.

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

[0111] As an effect of the Always-On PDU Session Indication IE being set to either "Always-On PDU Session Requested" or "Always-On PDU Session Not Allowed", the UE is informed about the status of the newly established PDU session. The apparatus 20 includes means, such as the processor 210, configured to cause the UE to consider the established PDU session as an Always-On PDU session in an instance where the Always-On PDU Session Indication IE is included in a PDU session establishment acknowledgement message and the Always-On PDU Session Indication IE is set to a value indicating "Always-On PDU Session Requested". See block 425 of Fig. 4. The apparatus 20 includes means, such as the processor 210, configured to cause the UE to not consider the established PDU session as an Always-On PDU session in an instance where the Always-On PDU Session Indication IE is included in a PDU session establishment acknowledgement message and the Always-On PDU Session Indication IE is set to a value indicating "Always-On PDU Session Not Allowed". See block 430 of Fig. 4.

[0112] The apparatus 20 includes means such as the processor 210 configured to maintain an always-on PDU session indication in the UE and the SMF when the inter-system change is from the N1 mode to the S1 mode. See block 435 of Fig. 4. The apparatus 20 includes means such as the processor 210 configured 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 the inter-system change is from the S1 mode to the N1 mode. See block 440 of Fig. 4.

[0113] 5 is a flow chart illustrating an example embodiment for requesting an always-on PDU session. In particular, the UE may initiate a UE requested PDU session establishment procedure, e.g., in an instance where the UE is configured to establish a new always-on PDU session, the UE shall include an always-on PDU session requested information element (IE) and set the value of the IE to "always-on PDU session requested", etc. Operations performed by the apparatus 200 to request an always-on PDU session utilizing the always-on attribute IE of the PDU session are illustrated in the flow chart of FIG. 5.

[0114] The apparatus 20 includes means, such as a processor 210, configured to cause transmission of a protocol data unit (PDU) session establishment request message. In some embodiments, for example in embodiments 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 comprises an IE set to a value indicating a request to establish a new always-on PDU session. See block 505 of FIG. 5.

[0115] When sending the PDU session establishment request message, the determination may be made, for example, by the SMF. When the device 20 determines that the requested PDU session is to be established as an always-on PDU session, the device 20 includes means, such as the processor 210, configured to receive a PDU session establishment acknowledgement message, the PDU session establishment acknowledgement message comprising an always-on PDU session indication IE, the always-on PDU session indication IE being set to a value indicating "always-on PDU session is requested". See block 510 of FIG. 5.

[0116] The device 20 may also include means, such as the processor 210, configured to receive a PDU session establishment acknowledgement message upon determining, for example by the SMF, that the requested PDU session is not to be established as an always-on PDU session, the PDU session establishment acknowledgement message comprising an always-on PDU session indication IE, the always-on PDU session indication IE being set to a value indicating "always-on PDU session not allowed". See block 515 of FIG. 5.

[0117] The device 20 includes means, such as the processor 210, configured to consider the 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 acknowledgement message and the always-on PDU session indication IE is set to a value indicating "always-on PDU session is requested". See block 520 of Fig. 5. The device 20 includes means, such as the processor 210, configured to not consider the 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 acknowledgement message and the always-on PDU session indication IE is set to a value indicating "always-on PDU session is not allowed". See block 525 of Fig. 5.

[0118] FIG. 6 illustrates a data flow diagram illustrating an exemplary embodiment of the present invention. In particular, FIG. 6 illustrates a PDU session modification procedure. For example, in some embodiments, for a PDN connection established in S1 mode (i.e., the UE and 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 a single registration mode in a network that does not support N26-less interworking, and the UE requests that the PDN connection be a always-on PDU session in 5GS, the UE shall include a Always-on PDU Session Requested IE and set the value of the IE to "always-on PDU session requested". See 610 in FIG. 6.

[0119] A decision is then made in the SMF as to whether the requested PDU session shall be established as a permanent PDU session. Once the decision is made, the SMF may, for example, provide a PDU session establishment command message to the UE, see 615 in Fig. 6. In detail, for a PDN connection established in S1 mode, if a network requested PDU session modification procedure is triggered by a UE requested PDU session modification procedure upon the first intersystem change from S1 mode to N1 mode, and the SMF determines based on the SMF's local policy or configuration and the permanent PDU session modification request message (if present) in the PDU session modification request message that the requested PDU session should be a permanent PDU session, the SMF shall include a permanent PDU session indication IE in the PDU session modification command message and set the value to "permanent PDU session is requested". Alternatively, for a PDN connection established in S1 mode, if, at the first inter-system change from S1 mode to N1 mode, a network requested PDU session modification procedure is triggered by a UE requested PDU session modification procedure and the SMF determines based on the SMF local policy or configuration and the Always-On PDU Session Requested IE (if present) in the PDU Session Modification Request message that the requested PDU session should not be a Always-On PDU Session and the UE included the Always-On PDU Session Requested IE, the SMF shall include a Always-On PDU Session Indication IE in the PDU Session Modification Command message and set the value to "Always-On PDU Session not allowed".

[0120] In those embodiments in which the network requested PDU session modification procedure is triggered by a UE requested PDU session modification procedure for a PDN connection established during S1 mode upon the first inter-system change from S1 mode to N1 mode, if the SMF determines that the requested PDU session is not to be a permanent PDU session based on the SMF local policy or configuration and the permanent PDU session requested IE (if present) in the PDU session modification request message and the UE did not include the permanent PDU session requested IE, the SMF does not include the permanent PDU session indication IE in the PDU session modification command message.

[0121] Thereafter, if the Always-On PDU Session Indication IE is included in the Modify PDU Session Command message and its value is set to "Always-On PDU Session Requested", the UE considers 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 Modify PDU Session Command message and its value is set to "Always-On PDU Session Not Allowed", the UE does 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 Modify PDU Session Command message, it does not consider the modified PDU session as an Always-On PDU Session.

[0122] In some embodiments, for a PDN connection established in S1 mode, upon the first intersystem 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 must be a permanent PDU session, the SMF shall include a permanent PDU session indication IE in the PDU session modification command message and set the value to "permanent PDU session is requested".

[0123] On the other hand, for a PDN connection established during S1 mode, during the first intersystem change from S1 mode to N1 mode, if the SMF determines based on the SMF local policy or configuration that the requested PDU session should not be a permanent PDU session, the SMF shall include the Persistent PDU Session Indication IE in the Modify PDU Session Command message and set the value to "Persistent PDU Session not allowed". Otherwise, the SMF shall not include the Persistent PDU Session Indication IE in the Modify PDU Session Command message.

[0124] Finally, if the Always-On PDU Session Indication IE is included in the Modify PDU Session Command message and its value is set to "Always-On PDU Session Requested", the UE shall consider the PDU session as an Always-On PDU Session. In the instance where the Always-On PDU Session Indication IE is included in the Modify PDU Session Command message and its value is set to "Always-On PDU Session Not Allowed", 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 higher layers on the Always-On PDU Session and to inform the higher layers that the indication regarding the Always-On PDU Session is ignored.

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

[0126] In an exemplary embodiment, the apparatus 200 comprises means, such as the processor 210, configured to receive from the UE a PDU session modification request message, the PDU session modification request message configured to indicate a request to modify a PDU session corresponding to a PDN connection established during S1 mode after an initial intersystem 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 does not comprise an always-on PDU session requested IE, see block 705 of Fig. 7. In an exemplary embodiment, the apparatus 200 comprises means, such as the processor 210, configured to determine whether to make the requested PDU session an always-on PDU session based on a local policy or configuration and the always-on PDU session requested IE in instances where the always-on PDU session requested IE is available, see block 710 of Fig. 7.

[0127] In an exemplary embodiment, the apparatus 200 comprises means, such as the processor 210, configured to cause the transmission of 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 "always-on PDU session is requested". See block 715 of Fig. 7. The apparatus 200 may also comprise means, such as the processor 210, configured to cause the transmission of 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 if the UE included an always-on PDU session requested IE in the PDU session establishment request message, or not comprising an always-on PDU session indication IE if the UE did not include an always-on PDU session requested IE in the PDU session establishment request message. See block 720 of Fig. 7.

[0128] Thereafter, in an exemplary embodiment, the apparatus 200 comprises means, such as the processor 210, configured to cause the UE to consider the 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 Modify Command message or where the Always-on PDU Session Indication IE is included in the PDU Session Modify Command message and the Always-on PDU Session Indication IE is set to a value indicating "always-on PDU session is requested". See block 725 of Fig. 7. The apparatus 200 may then also comprise means, such as the processor 210, configured to cause the UE to not 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 Modify Command message and the Always-on PDU Session Indication IE is set to a value indicating "always-on PDU session is not allowed". See block 730 of Fig. 7.

[0129] In an exemplary embodiment, the apparatus 200 comprises means, such as the processor 210, configured to determine, upon an inter-system change from the S1 mode to the N1 mode, whether the requested PDU session needs to be an always-on PDU session based on a local policy or configuration of the SMF, and, upon determining that the requested PDU session needs to be an always-on PDU session, set an always-on PDU session indication IE included in the PDU session modify command message to a value indicating "always-on PDU session is requested". See block 735 of FIG. 7.

[0130] In an exemplary embodiment, the apparatus 200 comprises means, such as the processor 210, configured to determine, upon an inter-system change from the S1 mode to the N1 mode, whether the requested PDU session needs to be an always-on PDU session based on a local policy or configuration of the SMF, and, upon determining that the requested PDU session does not need to be an always-on PDU session, set an always-on PDU session indication IE included in the PDU session modify command message to a value indicating "always-on PDU session not allowed". See block 740 of FIG. 7.

[0131] As noted above, Figure 8 illustrates operations performed by an apparatus, e.g., embodied by a UE, with respect to a modification procedure of a PDN connection established during S1 mode. That is, in another exemplary embodiment, a method, apparatus, and / or computer program product may be provided for enabling a modification procedure of a PDN connection established during S1 mode. Figure 8 is an exemplary flow chart illustrating a method of operating an exemplary apparatus, e.g., apparatus 200, embodied by a UE 102, performed in accordance with an embodiment of the present invention.

[0132] In an exemplary embodiment, the apparatus 200 comprises means, such as the processor 210, configured to cause transmission of a PDU session modification request message, the PDU session modification request message configured to indicate a request to modify a PDU session corresponding to a PDN connection established during S1 mode after an initial intersystem change from S1 mode to N1 mode. In some embodiments, the PDU session modification request message may comprise an IE, the value of which 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 comprise the always-on PDU session requested IE. See block 805 of FIG. 8.

[0133] A determination is then made in the SMF as to whether the requested PDU session should be an always-on PDU session. Once the determination is made, the SMF may provide, for example, a PDU session modify command message to the UE. In an exemplary embodiment, upon determining that the requested PDU session should be an always-on PDU session, the apparatus 200 comprises means, such as the processor 210, configured to receive a PDU session modify command message, the PDU session modify command message comprising an always-on PDU session indication IE, the always-on PDU session indication IE being set to a value indicating "always-on PDU session is requested". See block 810 of FIG. 8.

[0134] The apparatus 200 may also comprise means, such as the processor 210, configured to receive a PDU session modification command message upon determining that the requested PDU session is not 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 "always-on PDU session not allowed" if the UE included the always-on PDU session requested IE in the PDU session modification request message, or not comprising an always-on PDU session indication IE if the UE did not include the always-on PDU session requested IE in the PDU session modification request message. See block 815 of FIG. 8.

[0135] Thereafter, in an exemplary embodiment, the apparatus 200 comprises means, such as the processor 210, configured to 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 modify command message and the always-on PDU session indication IE is set to a value indicating "always-on PDU session is requested". See block 820 of FIG. 8.

[0136] The apparatus 200 may also include means, such as the processor 210, configured to not 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 always-on PDU session indication IE is set to a value indicating "always-on PDU session not allowed". See block 825 of FIG. 8.

[0137] As mentioned above, Figures 4, 5, 7 and 8 are flow charts of apparatus, methods and computer program products according to exemplary embodiments of the present invention. It will be appreciated that each block of the flow chart, and combinations of blocks in the flow chart, may be implemented by various means, such as hardware, firmware, processors, circuits, and / or other devices associated with the execution of software that includes one or more computer program instructions. For example, one or more of the above procedures may be embodied by computer program instructions. In this regard, computer program instructions embodying the above 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 appreciated, any such computer program instructions may be loaded into a computer or other programmable apparatus (e.g., hardware) to generate a machine, with the resulting computer or other programmable apparatus performing the functions specified in the flow chart blocks. These computer program instructions may also be stored in a computer readable memory to instruct the computer or other programmable apparatus to function in a particular manner, such that the instructions stored in the computer readable memory produce a product, and execution of the product performs the functions specified in the flow chart blocks. The computer program instructions may also be loaded into a computer or other programmable device to perform a series of operational steps on the computer or other programmable device to generate a computer-implemented process, such that the instructions executing on the computer or other programmable device provide acts that implement the functions specified in the flowchart blocks.

[0138] A computer program product is therefore defined as an example in which computer program instructions, such as computer readable program code portions, 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 Figures 4, 5, 7, and 8, etc. In other embodiments, computer program instructions, such as computer readable program code portions, need not be stored or otherwise embodied by a non-transitory computer readable storage medium, but may instead be embodied by a transitory medium, and still the computer program instructions, such as computer readable program code portions, when executed, are configured to perform the functions described above.

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

[0140] In some embodiments, certain of the operations described above may be modified or further augmented. Additionally, in some embodiments, additional optional operations may be included. Modifications, additions, or augmentations to the operations described above may be made in any order and in any combination.

[0141] Many modifications and other embodiments of the invention described herein will occur to one skilled in the art having the benefit of the teachings presented in the foregoing description and the associated drawings. It is to be understood, therefore, that the invention is not to 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. Moreover, while the foregoing description and the associated drawings describe exemplary embodiments in the context of certain exemplary combinations of elements and / or features, it is to be understood that different combinations of elements and / or features may be provided in alternative embodiments without departing from the scope of the appended claims. In this regard, combinations of elements and / or features other than those expressly described above may also be contemplated, for example as set forth in some of the appended claims. Although specific terms have been employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims

1. 1. A method for performing a service request procedure, the method comprising: receiving a protocol data unit (PDU) session modification request message from a user equipment (UE), the PDU session modification request message being configured to indicate a request to modify a PDU session corresponding to a PDN connection established during an 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 to make the PDU session a permanent protocol data unit (PDU) session; Based on a local policy or configuration and in an instance where the Always-On PDU Session Requested IE is available, determining whether to modify the requested PDU session to an Always-On PDU session; A method comprising:

2. In an instance where the result of the determining is determining to modify the requested PDU session to a permanent PDU session, the method further comprises: triggering the transmission of a PDU Session Modify Command message, the PDU Session Modify Command message comprising a Always-On PDU Session Indication IE, the Always-On PDU Session Indication IE being set to a value indicating "Always-On PDU Session is Requested"; The method of claim 1 further comprising:

3. In an instance where the result of the determining is determining not to modify the requested PDU session to a permanent PDU session, the method further comprises: Triggering the transmission of a PDU session modification command message, the PDU session modification command message comprising: When the UE includes the always-on PDU session requested IE in the PDU session establishment request message, the always-on PDU session indication IE is set to a value indicating "always-on PDU session is not allowed", or If the UE does not include the always-on PDU session requested IE in the PDU session establishment request message, the always-on PDU session indication IE is not included; The method of claim 1 further comprising:

4. When the inter-system change from the S1 mode to the N1 mode is performed, determining whether the requested PDU session needs to be a permanent PDU session based on the local policy or configuration of the SMF; When it is determined that the requested PDU session needs 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 that a permanent PDU session is requested; The method of claim 1 further comprising:

5. When the inter-system change from the S1 mode to the N1 mode is performed, determining whether the requested PDU session needs to be a permanent PDU session based on the local policy or configuration of the SMF; When it is determined 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 claim 1 further comprising:

6. An apparatus for performing a service request procedure, the apparatus comprising: At least one processor; When executed by the at least one processor, the apparatus comprises at least: receiving a protocol data unit (PDU) session modification request message from a user equipment (UE), the PDU session modification request message being configured to indicate a request to modify a PDU session corresponding to a PDN connection established during an 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 to make the PDU session a permanent protocol data unit (PDU) session; Based on a local policy or configuration and in an instance where the Always-On PDU Session Requested IE is available, determining whether to modify the requested PDU session to an Always-On PDU session; At least one memory storing instructions to cause the An apparatus comprising:

7. In an instance where the result of the determining is determining to modify the requested PDU session to a permanent PDU session, the instructions, when executed by the at least one processor, cause the apparatus to: triggering the transmission of a PDU Session Modify Command message, the PDU Session Modify Command message comprising a Always-On PDU Session Indication IE, the Always-On PDU Session Indication IE being set to a value indicating "Always-On PDU Session is Requested"; The apparatus of claim 6 , further comprising:

8. In an instance where the result of the determining is determining not to modify the requested PDU session to a permanent PDU session, the instructions, when executed by the at least one processor, cause the apparatus to: Triggering the transmission of a PDU session modification command message, the PDU session modification command message comprising: When the UE includes the always-on PDU session requested IE in the PDU session establishment request message, the always-on PDU session indication IE is set to a value indicating "always-on PDU session is not allowed", or If the UE does not include the always-on PDU session requested IE in the PDU session establishment request message, the always-on PDU session indication IE is not provided; The apparatus of claim 6 , further comprising:

9. The instructions, when executed by the at least one processor, cause the apparatus to: When the inter-system change from the S1 mode to the N1 mode is performed, determining whether the requested PDU session needs to be a permanent PDU session based on the local policy or configuration of the SMF; When it is determined that the requested PDU session needs 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 that a permanent PDU session is requested; The apparatus of claim 6 , further comprising:

10. The instructions, when executed by the at least one processor, cause the apparatus to: When the inter-system change from the S1 mode to the N1 mode is performed, determining whether the requested PDU session needs to be a permanent PDU session based on the local policy or configuration of the SMF; When it is determined 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 apparatus of claim 6 , further comprising:

11. A computer program for performing a service request procedure, said computer program comprising computer executable program code instructions, said computer executable program code instructions comprising program code instructions for performing the method according to any one of claims 1 to 5.

12. 1. A method for performing a service request procedure, the method comprising: establishing a protocol data unit (PDU) session corresponding to the packet data network (PDN) connection established during the S1 mode; generating a PDU session modification request message comprising an information element (IE) configured to indicate a request for the PDU session to be modified to be a permanent PDU session after an inter-system change from S1 mode to N1 mode; setting the IE in the PDU session modification request message to a value indicating a request that the PDU session be modified to be a permanent PDU session; triggering the transmission of the PDU Session Modification Request message; receiving a PDU Session Modification Command message in response to the PDU Session Modification Request message, the PDU Session Modification Command message including a Always-On PDU Session Indication IE, the Always-On PDU Session Indication IE indicating whether the PDU session is modified to be a Always-On PDU session; A method comprising:

13. 13. The method of claim 12, further comprising: determining that the PDU session is modified to be an always-on PDU session in an instance where the Always-on PDU Session Indication IE is included in the PDU Session Modify Command message and the Always-on PDU Session Indication IE is set to a value indicating "always-on PDU session is requested."

14. 13. The method of claim 12, further comprising: determining that the PDU session is not modified to be 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 "always-on PDU session is not allowed."

15. An apparatus for performing a service request procedure, comprising at least one processor and at least one memory storing instructions that, when executed by said at least one processor, cause said apparatus to perform at least the method according to any one of claims 12 to 14.

16. A computer program for performing a service request procedure, said computer program comprising computer executable program code instructions, said computer executable program code instructions comprising program code instructions for performing the method according to any one of claims 12 to 14.

17. 1. A method for performing a service request procedure, the 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; In an instance where the PDU session establishment request message comprises an Always-On PDU Session Requested information element (IE), determining whether the UE requests to establish the PDU session as a Always-On PDU session based on a value set in the Always-On PDU Session Requested IE; In an instance in which the UE requests to establish the PDU session as a permanent PDU session, determining whether to establish the PDU session as a permanent PDU session; generating a PDU session establishment acknowledgement message including a permanent PDU session indication IE indicating whether the PDU session is established as a permanent PDU session; A method comprising:

18. When it is determined that the PDU session is established as a constant-connection PDU session, setting the constant-connection PDU session indication IE in the PDU session establishment acknowledgement message to a value indicating that the PDU session is established as a constant-connection PDU session; triggering transmission of the PDU Session Establishment Acknowledgement message towards the UE; and 20. The method of claim 17, further comprising:

19. When it is determined that the PDU session is not established as a constant-connection PDU session, setting the constant-connection PDU session indication IE in the PDU session establishment acknowledgement message to a value indicating that the PDU session is not established as a constant-connection PDU session; triggering transmission of the PDU Session Establishment Acknowledgement message towards the UE; and 20. The method of claim 17, further comprising:

20. When changing between systems from N1 mode to S1 mode, the PDU session is maintained as a constant-connection PDU session, and the constant-connection PDU session indication is maintained.

20. The method of claim 17, further comprising:

21. When the inter-system change is made from the S1 mode to the N1 mode, based on the always-on PDU session indication, determining whether the PDU session transferred from an evolved packet system (EPS) is a always-on PDU session.

21. The method of claim 20, further comprising:

22. An apparatus for performing a service request procedure, comprising at least one processor and at least one memory storing instructions which, when executed by said at least one processor, cause said apparatus to perform at least the method of any one of claims 17 to 21.

23. A computer program for performing a service request procedure, said computer program comprising computer executable program code instructions, said computer executable program code instructions comprising program code instructions for performing the method according to any one of claims 17 to 21.

24. 1. A method for performing a service request procedure, the method comprising: generating a protocol data unit (PDU) session establishment request in a user equipment (UE), the PDU session establishment request indicating a request to establish a PDU session; Determining, in the UE, whether to request to establish the PDU session as a permanent PDU session; Including an always-on PDU session requested information element (IE) in the PDU session establishment request message, 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 UE determines that it requests to establish the PDU session as a permanent PDU session, setting the permanent PDU session requested IE in the PDU session establishment request message to a value indicating a request to establish the PDU session as a permanent PDU session; triggering the transmission of the PDU session establishment request message; receiving a PDU session establishment acknowledgement message in response to the PDU session establishment request message, the PDU session including a permanent connection PDU session indication IE configured to indicate whether the PDU session is established as a permanent connection PDU session; In the UE, determining whether the PDU session is established as a constant-connection PDU session based on a value set in the constant-connection PDU session indication IE; A method comprising:

25. In an instance in which 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", determining that the PDU session is established as a always-on PDU session.

25. The method of claim 24, further comprising:

26. In an instance in which 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 allowed", determining that the PDU session is established but not as a always-on PDU session.

25. The method of claim 24, further comprising:

27. An apparatus for performing a service request procedure, comprising at least one processor and at least one memory storing instructions which, when executed by said at least one processor, cause said apparatus to perform at least the method of any one of claims 24 to 26.

28. A computer program for performing a service request procedure, said computer program comprising computer executable program code instructions, said computer executable program code instructions comprising program code instructions for performing the method according to any one of claims 24 to 26.

29. 1. A method for performing a service request procedure, the method comprising: receiving a protocol data unit (PDU) session establishment request message from a user equipment (UE), the PDU session establishment request message being 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 being set to a value indicating a request to establish the PDU session as a always-on PDU session; In an instance where the Always-On PDU Session Requested IE is set to a value indicating a request to establish the Always-On PDU Session, determining whether to establish the requested PDU session as a Always-On PDU Session based on a local policy or configuration; Establishing the requested PDU session as a permanent PDU session in N1 mode; In an instance where an inter-system change from the N1 mode to the S1 mode is performed, maintaining a constant connection PDU session indication associated with the constant connection PDU session; A method comprising:

30. When it is determined that the requested PDU session is established as a permanent PDU session, a PDU session establishment acknowledgement message is sent to the UE, the PDU session establishment acknowledgement message comprising a permanent PDU session indication IE, and the permanent PDU session indication IE is set to a value indicating that a "permanent PDU session is requested".

30. The method of claim 29, further comprising:

31. When it is determined that the requested PDU session is not to be established as a permanent PDU session, a PDU session establishment acknowledgement message is sent to the UE, the PDU session establishment acknowledgement message being: A constant-connection PDU session indication IE, which is set to a value indicating "constant-connection PDU session is not allowed" when the UE includes the constant-connection PDU session requested IE in the PDU session establishment request message. To be prepared 30. The method of claim 29, further comprising:

32. When an inter-system change is made from an S1 mode to an N1 mode, based on the always-on PDU session indication, determining whether the PDU session transferred from an evolved packet system (EPS) is a always-on PDU session.

30. The method of claim 29, further comprising:

33. An apparatus for performing a service request procedure, comprising at least one processor and at least one memory storing instructions which, when executed by said at least one processor, cause said apparatus to perform at least the method of any one of claims 29 to 32.

34. A computer program for performing a service request procedure, said computer program comprising computer executable program code instructions, said computer executable program code instructions comprising program code instructions for performing the method of any one of claims 29 to 32.

35. 1. A method, comprising: including a permanently connected protocol data unit (PDU) session requested information element (IE) in a PDU session establishment request message configured to indicate a request to establish a PDU session; Setting the always-on PDU session requested IE in the PDU session establishment request message to a value indicating a request to establish the PDU session as a always-on PDU session; triggering the transmission of the PDU session establishment request message; Receiving a PDU session establishment acknowledgement message having a constant connection PDU session indication IE, wherein the constant connection PDU session indication IE is set to a value indicating "a constant connection PDU session is requested" or a value indicating "a constant connection PDU session is not allowed"; Equipped with In an instance where the requested PDU session is established as a permanent connection PDU session in N1 mode, the permanent connection PDU session indication IE is configured to maintain the permanent connection PDU session indication IE associated with the permanent connection PDU session upon an inter-system change from N1 mode to S1 mode. method.

36. In an instance in which 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 considered to be a always-on PDU session.

36. The method of claim 35, further comprising:

37. In an instance in which 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 to be a always-on PDU session.

36. The method of claim 35, further comprising:

38. An apparatus for performing a service request procedure, comprising at least one processor and at least one memory storing instructions which, when executed by said at least one processor, cause said apparatus to perform at least the method of any one of claims 35 to 37.

39. A computer program for performing a service request procedure, said computer program comprising computer executable program code instructions, said computer executable program code instructions comprising program code instructions for performing the method of any one of claims 35 to 37.

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