Method for processing CIoT data for invalid PDU session ID

Abstract

The present disclosure relates to a 5G or 6G communication system for supporting a higher data transmission rate. Disclosed is a method of operating a user equipment (UE) operable to communicate with a telecommunications network, comprising the steps of: the UE transmitting a control plane service request (CPSR) message with cellular Internet of Things (CIoT) user data associated with a protocol data unit (PDU) session to the telecommunications network; the UE receives, from the telecommunications network, a service acceptance message indicating that the PDU session is inactive in the network; and the UE verifies whether the PDU session has the same identification as the identification of the PDU session included in the CPSR message with the CIoT user data, and if so, the UE determines that the CIoT user data is not successfully transmitted to the telecommunications network or the final recipient.

Description

Technical Field

[0001] The present disclosure relates to Cellular Internet of Things (CIoT) data processing in a telecommunication system when there is no routing context in an Access and Mobility Management Function (AMF).

[0002] This application is based on and claims priority under 35 U.S.C. §119 to Indian Patent Application No. 202231055987 filed on September 29, 2022, Indian Patent Application No. 202231058522 filed on October 13, 2022, and UK Patent Application No. 2314696.2 filed on September 25, 2023, the disclosures of the foregoing patent applications are incorporated herein by reference in their entirety. Background Art

[0003] 5G mobile communication technology defines a wide frequency band, making high transmission rates and new services possible, and can be implemented not only in "below 6 GHz" frequency bands such as 3.5 GHz, but also in "above 6 GHz" frequency bands called mmWave including 28 GHz and 39 GHz. In addition, 6G mobile communication technology (called super 5G system) has been considered to be implemented in terahertz (THz) frequency bands (e.g., 95 GHz to 3 THz frequency bands) to achieve a transmission rate 50 times faster than 5G mobile communication technology and an ultra-low latency of one tenth of 5G mobile communication technology.

[0004] In the early stage of the development of 5G mobile communication technology, in order to support services and meet performance requirements related to enhanced mobile broadband (eMBB), ultra-reliable low latency communication (URLLC) and massive machine type communication (mMTC), beamforming and massive MIMO for alleviating radio wave path loss and increasing radio wave transmission distance in mmWave, dynamic operation of parameter sets (e.g., operating multiple subcarrier spacings) and time slot formats supporting efficient utilization of mmWave resources, initial access technology for supporting multi-beam transmission and broadband, definition and operation of bandwidth parts (BWPs), new channel coding and decoding methods (such as low-density parity-check (LDPC) codes for large amounts of data transmission and polar codes for highly reliable control information transmission), L2 preprocessing, and standardization of network slicing for providing dedicated networks dedicated to specific services have been underway.

[0005] Currently, discussions are ongoing on improvements and performance enhancements of initial 5G mobile communication technologies in consideration of the services that they will support, and there is already physical layer standardization on technologies such as Vehicle-to-Everything (V2X) for assisting driving determination of autonomous vehicles based on information about the location and status of the vehicle sent by the vehicle and for enhancing user convenience, NR-U (New Radio Unlicensed) designed to enable system operation to comply with various regulatory-related requirements in unlicensed bands, NR UE power saving, a non-terrestrial network (NTN) as UE-satellite direct communication for providing coverage in areas where communication with terrestrial networks is unavailable, and positioning.

[0006] In addition, standardization is being conducted in air interface architecture / protocols on technologies such as Industrial Internet of Things (IIoT) for supporting new services through interworking and integration with other industries, Integrated Access and Backhaul (IAB) for providing nodes for network service area expansion by supporting wireless backhaul links and access links in an integrated manner, mobility enhancement including conditional handover and dual active protocol stack (DAPS) handover, and two-step random access (2-step RACH for NR) for simplifying the random access procedure. Standardization is also being conducted in system architecture / services on 5G baseline architecture (e.g., service-based architecture or service-based interface) for combining network function virtualization (NFV) and software defined network (SDN) technologies, and mobile edge computing (MEC) for receiving services based on UE location.

[0007] As 5G mobile communication systems are commercialized, an exponentially increasing number of connected devices will be connected to the communication network, and therefore, it is expected that enhanced functions and performance of 5G mobile communication systems and integrated operations of connected devices will be necessary. To this end, new research is planned in relation to efficiently supporting extended reality (XR) such as augmented reality (AR), virtual reality (VR), mixed reality (MR), etc., 5G performance improvement and complexity reduction by utilizing artificial intelligence (AI) and machine learning (ML), AI service support, metaverse service support, and drone communication.

[0008] Furthermore, such development of 5G mobile communication systems will serve as a foundation for developing not only new waveforms for providing coverage in the terahertz band for 6G mobile communication technology, multi-antenna transmission technologies (such as full-dimensional MIMO (FD-MIMO), array antennas, and large antennas), metamaterial-based lenses and antennas for improving coverage of terahertz band signals, high-dimensional spatial multiplexing technologies using orbital angular momentum (OAM), and reconfigurable smart surfaces (RIS), but also full-duplex technologies for improving the frequency efficiency of 6G mobile communication technology and improving system networks, AI-based communication technologies for implementing system optimization by utilizing satellites and artificial intelligence (AI) from the design stage and internalizing end-to-end AI support functions, and next-generation distributed computing technologies for implementing services with a complexity level that exceeds the limits of UE operating capabilities by utilizing ultra-high performance communication and computing resources. Summary of the invention

[0009] Solution to the problem

[0010] According to an embodiment of the present disclosure, a method for operating a user equipment (UE) operable to communicate with a telecommunications network (e.g., a network entity) is provided. The method may include the following steps: the UE sends a control plane service request CPSR message with cellular Internet of Things (CIoT) user data associated with a protocol data unit (PDU) session to the telecommunications network; the UE receives a service acceptance (SERVICE ACCEPT) message indicating that the PDU session is inactive in the network from the telecommunications network; and the UE verifies whether the PDU session has the same identifier as the identifier of the PDU session included in the CPSR message with the CIoT user data, and if so, the UE determines that the CIoT user data is not successfully sent to the telecommunications network or the final recipient.

[0011] Advantageous Effects of the Invention

[0012] According to an embodiment of the present disclosure, a method and apparatus for Cellular Internet of Things (CIoT) data processing in a telecommunication system are provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] For a more complete understanding of the present disclosure and its advantages, reference is now made to the following description taken in conjunction with the accompanying drawings, in which like reference numerals represent like parts:

[0014] Figure 1 A flowchart of a UE method for CIoT data processing according to an embodiment of the present disclosure is shown;

[0015] Figure 2 A flow chart of a network entity method for CIoT data processing according to an embodiment of the present disclosure is shown;

[0016] Figure 3shows the internal configuration of a base station according to an embodiment of the present disclosure; and

[0017] Figure 4 The internal structure of a user equipment according to an embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0018] According to the present disclosure, there is provided an apparatus and a method as set out in the accompanying claims. Further features of the present disclosure will be apparent from the dependent claims and the subsequent description.

[0019] According to an embodiment of the present disclosure, a method for operating a UE operable to communicate with a telecommunications network is provided. The method may include the following steps: the UE sends a CPSR message with CIoT user data associated with a PDU session to the telecommunications network; the UE receives a service acceptance message from the telecommunications network indicating that the PDU session is inactive in the network; and the UE verifies whether the PDU session has the same identifier as the identifier of the PDU session included in the CPSR message with the CIoT user data, and if so, the UE determines that the CIoT user data is not successfully sent to the telecommunications network or the final recipient.

[0020] In an embodiment, the service accept message may include a PDU session status information element (IE) indicating that the PDU session corresponding to the PDU session ID received in the CPSR message is inactive.

[0021] According to an embodiment of the present disclosure, a method of operating a telecommunication network operable to communicate with a UE is provided. The method comprises the following steps: the telecommunication network receives a CPSR message having CIoT user data associated with a PDU session from the UE; if the telecommunication network determines that the PDU session is inactive, the telecommunication network discards the CIoT data; and

[0022] The telecommunications network sends a Service Accept message to the UE indicating that the PDU Session is not active in the network.

[0023] In an embodiment, the AMF is operable in the telecommunications network to receive a CPSR message and send a service acceptance message.

[0024] In an embodiment, the service accept message includes a PDU session status information element (IE) indicating that the PDU session corresponding to the PDU session ID received in the CPSR message is inactive.

[0025] Embodiments of the invention

[0026] Discussed below Figures 1 to 4The various embodiments used to describe the principles of the present disclosure in this patent document are illustrative only and should not be interpreted in any way to limit the scope of the present disclosure. Those skilled in the art will understand that the principles of the present disclosure can be implemented in any appropriately arranged system or device.

[0027] Before the following description is made, it may be helpful to set forth the definitions of certain words and phrases used throughout this patent document.The term "coupling" and its derivatives refer to any direct or indirect communication between two or more elements, whether or not these elements are in physical contact with each other.The terms "send", "receive" and "communication" and their derivatives cover both direct and indirect communication.The terms "include" and "comprise" and their derivatives mean including but not limited to.The term "or" is inclusive, meaning and / or.The phrase "associated with..." and its derivatives mean including, included in, interconnected with, included in, connected to or connected with, coupled to or coupled with, can communicate with, collaborate with, interlace, juxtapose, be close to, be bound to or bound with, have, have the property of, have to ... The functionality associated with any particular controller may be centralized or distributed, whether local or remote. The phrase "at least one of" when used with a list of items means that different combinations of one or more of the listed items may be used, and that only one of the items in the list may be required. For example, "at least one of A, B, and C" includes any of the following combinations: A, B, C, A and B, A and C, B and C, and A and B and C.

[0028] In addition, the various functions described below can be implemented or supported by one or more computer programs, each of which is formed by a computer-readable program code and contained in a computer-readable medium. The terms "application" and "program" refer to one or more computer programs, software components, instruction sets, processes, functions, objects, classes, instances, related data or a part thereof suitable for implementation with a suitable computer-readable program code. The phrase "computer-readable program code" includes any type of computer code, including source code, object code and executable code. The phrase "computer-readable medium" includes any type of medium that can be accessed by a computer, such as a read-only memory (ROM), a random access memory (RAM), a hard drive, a compact disk (CD), a digital video disc (DVD) or any other type of memory. "Non-transitory" computer-readable media does not include wired, wireless, optical or other communication links that transmit temporary electrical signals or other signals. Non-transitory computer-readable media include media that can permanently store data and media that can store data and rewrite it later, such as rewritable optical disks or erasable memory devices.

[0029] Definitions for certain other words and phrases are provided throughout this patent document. Those of ordinary skill in the art should understand that in many, if not most instances, such definitions apply to prior, as well as future uses of such defined words and phrases.

[0030] The fifth generation system (5GS) (and evolved packet system (EPS)) allows CIoT devices or user equipment (UE) to send data through the control plane (CP). For example, a UE in idle mode uses a CPSR message to send data through the non-access stratum (NAS) (i.e., through the control plane). In this case, the service request process associated with the transmission of the CPSR message is completed by the AMF sending a service acceptance message.

[0031] When sending a CPSR message for CIoT data, the UE includes a PDU Session Identifier (ID) which identifies the session for which the data is being sent. This enables the AMF to identify to which Session Management Function (SMF) the data can be forwarded.

[0032] In some cases, although the UE may have the PDU Session ID and context locally (in the UE), the network may have released the PDU Session, which may not have been communicated to the UE, for example, because the UE is in idle mode. In this way, the UE, unaware of this event, may try to send data to the identified PDU Session that ultimately does not exist in the network. 3GPP TS24.501 recognizes such scenarios and specifies the following processing on the network side:

[0033] g) the received CONTROL PLANE SERVICE REQUEST message has a Data Type field in the CIoT Small Data Container IE indicating "Control Plane User Data", or the received CONTROL PLANE SERVICE REQUEST message has a Payload Container Type IE set to "CIoT User Data Container", and:

[0034] 1) The AMF does not have a PDU Session Routing Context for the PDU Session ID and the UE; or

[0035] 2) AMF unsuccessfully attempts to forward the User Data Container and PDU Session ID,

[0036] The AMF may then send the CIoT user data container or control plane user data that was not forwarded back to the UE as specified in subclause 5.4.5.3.1 Case 1 1) or Case 1 2).

[0037] According to the above description, in the case of the identified scenario described in the bullet point part 1) of the cited text, the network can send the unforwarded data back to the UE. However, the network uses the DL NAS transmission (DL NAS TRANSPORT) process to do so, that is, the network sends a DL NAS TRANSPORT message to send the unforwarded data back to the UE. The following describes the AMF behavior of the above-cited case 1 1:

[0038] For case 1 1) in subclause 5.4.5.3.1, i.e. when sending a single uplink CIoT user data container or control plane user data that is not forwarded due to routing failure, the AMF may:

[0039] a) Include the PDU Session ID in the PDU Session ID IE;

[0040] b) Set the Payload Container Type IE to “CIoT User Data Container”;

[0041] c) setting the Payload Container IE to the CIoT User Data Container or Control Plane User Data that is not forwarded; and

[0042] d) Set the 5GMM Cause IE to 5GMM Cause #90 “Payload not forwarded”.

[0043] NOTE 4: For case 1 1) in subclause 5.4.5.3.1, this also applies to a single uplink CIoT user data container or control plane user data in a control plane service request message that was not forwarded due to routing failure.

[0044] In summary, the following observations can be made:

[0045] The UE may send a CPSR message containing CIoT user data for a PDU session without routing context; and

[0046] ●The network may send data back to the UE using DL NAS TRANSPORT message and include 5GMM cause #90.

[0047] The following concerns the Mobility Management Entity (MME) processing of EPS Session Management (ESM) messages for inactive EPS bearer identities.

[0048] In EPS, the UE may send a NAS ESM message without a valid EPS bearer identifier. In this case, the MME rejects the NAS ESM message and indicates that the EPS bearer identifier is invalid.

[0049] For example, 3GPP TS 24.301 specifies the following behavior of the MME when this scenario occurs during a bearer resource modification procedure initiated by the UE:

[0050] a) Unknown EPS bearer context:

[0051] If the EPS bearer identifier provided in the EPS bearer identifier IE of the packet filter in the BEARER RESOURCE MODIFICATON REQUEST message indicates an EPS bearer identifier value and this does not belong to any activated EPS bearer context, the MME may reply with a BEARER RESOURCE MODIFICATON REJECT message with ESM cause #43 “Invalid EPS bearer identifier”.

[0052] It can be seen that it is already possible to send an ESM message whose EPS bearer identifier is judged to be invalid. In this case, the network rejects the message, as shown above.

[0053] A problem experienced by the above-mentioned related art is that the UE may erroneously conclude that the CIoT data has been successfully transmitted when it has not been successfully transmitted.

[0054] To illustrate the problem, it is useful to consider the following scenario:

[0055] ●UE sends a CPSR message containing CIoT user data;

[0056] The AMF does not have any routing context for the associated PDU Session ID;

[0057] The AMF does not send CIoT user data back to the UE (as this step is optional).

[0058] The AMF sends a Service Accept message (which is required to complete the Service Request process) without any indication of failure to route the CIoT User Data;

[0059] ● Because no indication of failure is received, the UE concludes that the CIoT user data has been successfully transmitted. The NAS layer in the UE can notify the upper layer (e.g., application or 5GSM entity) that the data has been successfully sent;

[0060] ● Because no indication of a failed transmission is received, the upper layers may discard the CIoT user data content. This therefore prohibits the UE from resending data that may actually carry critical information for the application server; and / or

[0061] ●The above may be repeated multiple times because the UE may eventually assume that the CIoT data was sent successfully, but this is not the case.

[0062] The same problem may also occur in the following scenarios:

[0063] ●UE sends a CPSR message containing CIoT user data;

[0064] The AMF does not have any routing context for the associated PDU Session ID;

[0065] The AMF completes the service request by sending a service acceptance message; and / or

[0066] ●AMF sends CIoT user data back to UE using DL NAS TRANSPORT message.

[0067] For the latter scenario, the UE's receipt of a service acceptance message prior to the DL NAS TRANSPORT message may cause the UE to conclude that the CIoT user data was successfully sent. This is because the service acceptance message currently has no indication of failure, and when received by the UE, it may cause the UE to conclude that the service request process for sending CIoT user data was indeed successful. Afterwards, the reception of a DL NAS TRANSPORT message containing data that was not actually forwarded by the AMF may be quite late. For example, the UE's reception of a service acceptance may have triggered an indication of successful data delivery to the upper layer, as a result of which the upper layer may have actually discarded the content. Then, the subsequent reception of a relatively late DL NAS TRANSPORT message with an indication of unsuccessful data forwarding by the AMF may not be of much use, because the UE has already notified the upper layer of success. The indication now appears to be contradictory.

[0068] Therefore, the above scenario leads to a situation where the UE assumes successful CIoT user data delivery, when in reality no such conclusion can be drawn. This leads to the problem that the application layer "believes" that data has been successfully delivered through the NAS layer, when in fact the data has not been delivered, and no notification is actually received, or contradictory status indications are received.

[0069] Another issue is the lack of MME handling of CIoT user data with invalid EPS bearer identifiers. If a UE (in S1 mode, i.e., in EPS or in LTE) sends CIoT user data in an ESM DATA TRANSPORT message containing an invalid EPS bearer identifier, the MME behavior is unknown because the handling is not defined in 3GPP TS 24.301. Thus, the UE does not get any indication about this and can therefore assume that the CIoT user data has been successfully sent.

[0070] It is therefore an object of embodiments of the present disclosure to address these and other shortcomings in the related art, whether mentioned herein or not.

[0071] According to the present disclosure, there is provided an apparatus and a method as set out in the accompanying claims. Further features of the present disclosure will be apparent from the dependent claims and the subsequent description.

[0072] According to a first aspect of the present disclosure, there is provided a method of operating a user equipment (UE) operable to communicate with a telecommunications network, the method comprising the following steps: the UE sends a CPSR message having cellular Internet of Things (CIoT) user data associated with a PDU session to the telecommunications network; the UE receives a service acceptance message from the telecommunications network indicating that the PDU session is inactive in the network; and the UE verifies whether the PDU session has an identifier that is the same as an identifier of the PDU session included in the CPSR message having the CIoT user data, and if so, the UE determines that the CIoT user data is not successfully sent to the telecommunications network or to a final recipient.

[0073] In an embodiment, the service accept message includes a PDU session status information element (IE) indicating that the PDU session corresponding to the PDU session ID received in the CPSR message is inactive.

[0074] According to a second aspect of the present disclosure, a UE arranged to perform the method of the first aspect is provided.

[0075] According to a third aspect of the present disclosure, there is provided a method of operating a telecommunications network operable to communicate with a UE, the method comprising the following steps: the telecommunications network receives a CPSR message having CIoT user data associated with a PDU session from the UE; if the telecommunications network determines that the PDU session is inactive, the telecommunications network discards the CIoT data; and the telecommunications network sends a service acceptance message to the UE indicating that the PDU session is inactive in the network.

[0076] In an embodiment, the AMF is operable in the telecommunications network to receive a CPSR message and send a service acceptance message.

[0077] In an embodiment, the service accept message includes a PDU session status IE indicating that the PDU session corresponding to the PDU session ID received in the CPSR message is inactive.

[0078] According to a fourth aspect of the present disclosure, there is provided a telecommunications network arranged to perform the method of the third aspect.

[0079] According to a fifth aspect of the present disclosure, there is provided a telecommunication system comprising the UE of the second aspect and the telecommunication network of the fourth aspect.

[0080] While certain preferred embodiments of the present disclosure have been shown and described, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the scope of the present disclosure as defined in the appended claims.

[0081] For a better understanding of the present disclosure, and to show how embodiments of the present disclosure may be implemented, reference will now be made, by way of example only, to the accompanying drawings, in which:

[0082] Figure 1 A flowchart of a UE method for CIoT data processing according to an embodiment of the present disclosure is shown; and

[0083] Figure 2 A flowchart of a network entity method for CIoT data processing according to an embodiment of the present disclosure is shown.

[0084] The first embodiment of the present disclosure defines a new AMF behavior for processing CIoT user data when there is no routing information.

[0085] To solve the problems that have been previously pointed out, there are several possible options.

[0086] Note that the details set out below are for the case where the AMF receives a CPSR message containing CIoT user data, but the AMF does not have a PDU session routing context (or information) associated with the PDU session ID, so the AMF cannot forward the data to the SMF. It should be noted that this can also mean that the PDU session ID included in the CPSR message is considered to be an inactive session (or that the PDU session ID is for an inactive session or a session that has been released by the network).

[0087] In one embodiment, the AMF sends a DL NAS TRANSPORT message including CIoT user data that is not forwarded (and therefore sent back to the UE) before sending the SERVICE ACCEPT message.

[0088] In such an embodiment, when the AMF receives CIoT user data in a CPSR message and the AMF does not have a PDU session routing context, the AMF may send the CIoT user data back to the UE in a DL NAS TRANSPORT message, as already specified in 3GPP TS24.501. However, it is important and therefore stated here that the DL NAS TRANSPORT message may be sent before the AMF sends the Service Accept message to the UE. This ensures that the UE is able to conclude that the CIoT user data was not successfully sent even when a Service Accept message is subsequently received.

[0089] In addition, the AMF may send a service acceptance message and include a PDU session status IE in the message. In addition, the AMF may set the PDU session ID received in the CPSR message and for which there is no PDU session routing context, so that the corresponding bit position in the IE indicates that the PDU session is inactive in the network. For example, the PDU session identifier (PSI) bit position corresponding to the PDU session ID (received by the AMF in the CPSR message and for which there is no PDU session routing context) may be set by the AMF to a value of 0, i.e., "the 5GSM state of the corresponding PDU session is PDU SESSION INACTIVCE" (see 3GPP TS24.501).

[0090] During the service request process in which the UE has sent a CPSR message with CIoT user data, if the UE receives a DL NASTRANSPORT message with (unforwarded) CIoT user data and a 5GMM cause value #90 "Payload not forwarded", the UE may notify the upper layer that the CIoT user data was not sent successfully.

[0091] Alternatively, if a DL NAS TRANSPORT message is received before the SERVICE ACCEPT message, the UE acts as provided.

[0092] During the service request process in which the UE has sent a CPSR message with CIoT user data, if the UE receives a service accept message with a PDU session status IE such that the PDU session ID that the UE has included in the CPSR message is now set to indicate or now indicates (in the PDU session status IE) that the PDU session is inactive, the UE may consider that the CIoT user data sent in the CPSR message has not been successfully sent or delivered or transmitted by the network. The UE may notify the upper layer that the CIoT user data has not been successfully transmitted. The UE may also send a PDU session ID to the upper layer to specify which PDU session ID is being referenced.

[0093] Note that the UE sending the provided indication to upper layers may imply any of the following alternatives with respect to the above provided indication (optionally with the PDU Session ID in question):

[0094] The UE NAS 5GMM entity notifies the 5GSM entity, which in turn notifies the application layer;

[0095] UE NAS 5GSM entity notifies the application layer; and

[0096] ●UE NAS 5GMM entity notifies the application layer.

[0097] In one embodiment, the AMF sends a 5GMM STATUS message to the UE.

[0098] In such an embodiment, when the identified scenario as described above occurs, the AMF may send a 5GMM STATUS message to the UE. The AMF may set the 5GMM cause value to any existing value (e.g., #90) or to a new value. Optionally, the AMF may include the PDU Session ID as a new field in the 5GMM STATUS message. Preferably, the AMF sends the 5GMM STATUS message to the UE before sending the Service Accept message.

[0099] During the service request process in which the UE has sent a CPSR message with CIoT user data, if the UE receives a 5GMM STATUS message (optionally with a PDU session ID, optionally wherein the message may be received before or after receiving the service acceptance message), the UE may consider that the CIoT user data sent in the CPSR message has not been successfully sent or delivered or transmitted by the network. The UE may notify the upper layer that the CIoT user data has not been successfully transmitted.

[0100] If a PDU Session ID is received, the UE may also send the PDU Session ID to the upper layer to specify which PDU Session ID is being referenced. In this case, the UE may also locally deactivate the PDU session identified by the PDU Session ID, where the identification is explicitly received by the UE or determined by the UE to be a PDU Session ID sent by the UE in a previous NAS message (such as a CPSR message or an UL NAS TRANSPORT message). Note that local deactivation of the session may also be performed by the UE for any of the options described herein. In addition, the UE may take this action regardless of the content sent by the UE, for example, the content may be CIoT user data or any 5GSM message. For example, whenever a cause value #90 is received in any NAS message, the UE may act as described.

[0101] Note that the UE sending the provided indication to upper layers may imply any of the following alternatives with respect to the above provided indication (optionally with the PDU Session ID in question):

[0102] The UE NAS 5GMM entity notifies the 5GSM entity, which in turn notifies the application layer;

[0103] UE NAS 5GSM entity notifies the application layer; and

[0104] ●UE NAS 5GMM entity notifies the application layer.

[0105] In one embodiment, the AMF sends a service acceptance message to the UE and includes an indication that the CIoT user data is not forwarded.

[0106] In this option, when the identified scenario as described above occurs, the AMF sends a Service Accept message to the UE and also includes an indication that the CIoT user data (received in the CPSR message) was not successfully forwarded or transmitted. The AMF may include a new indication or may include a 5GMM cause value and set the indication or value to #90 or any other new value that may indicate that the transmission of the CIoT user data was not successful. The Service Accept message may also include a PDU Session ID to refer to the session for which the CIoT user data was not successfully transmitted. The Service Accept may also include CIoT user data that was not forwarded by the AMF.

[0107] During the service request procedure in which the UE has sent a CPSR message with CIoT user data, if the UE receives a service accept message (optionally with a PDU session ID) with an indication that the CIoT user data was not successfully transmitted, the UE may notify the upper layer that the CIoT user data was not successfully transmitted. If a PDU session ID is received, the UE may also send the PDU session ID to the upper layer to specify which PDU session ID is being referenced. If a CIoT user data transmission (not forwarded by the AMF) is received, the UE may also send a CIoT user data transmission to the upper layer.

[0108] Note that the UE sending an indication to upper layers may mean any of the following alternatives with respect to the indication provided above (optionally with the PDU Session ID in question):

[0109] The UE NAS 5GMM entity notifies the 5GSM entity, which in turn notifies the application layer;

[0110] UE NAS 5GSM entity notifies the application layer; and

[0111] ●UE NAS 5GMM entity notifies the application layer.

[0112] In one embodiment, the AMF sends a service reject message to the UE and includes an indication that the CIoT user data is not forwarded.

[0113] In this option, when the identified scenario as described above occurs, the AMF sends a service rejection message to the UE and also includes an indication that the CIoT user data (received in the CPSR message) was not successfully forwarded or transmitted. The AMF may include a new indication, or may include a 5GMM cause value and set the indication or value to #90 or any other new value that may indicate that the transmission of the CIoT user data was not successful. The service rejection message may also include a PDU session ID to refer to the session for which the CIoT user data was not successfully transmitted. The service acceptance may also include the CIoT user data that was not forwarded by the AMF.

[0114] During the service request process in which the UE has sent a CPSR message with CIoT user data, if the UE receives a service reject message (optionally with a PDU Session ID) with an indication that the CIoT user data was not successfully transmitted (for example, in the form of a new or existing 5GMM cause value), the UE may notify the upper layer that the CIoT user data was not successfully transmitted. If a PDU Session ID is received, the UE may also send the PDU Session ID to the upper layer to specify which PDU Session ID is being referenced. If a CIoT user data transmission (not forwarded by the AMF) is received, the UE may also send the CIoT user data transmission to the upper layer. Note that the UE remains in (or enters) the 5GMM-REGISTERED state.

[0115] Note that the UE sending an indication to upper layers may mean any of the following alternatives with respect to the above indication (optionally with the PDU Session ID in question):

[0116] The UE NAS 5GMM entity notifies the 5GSM entity, which in turn notifies the application layer;

[0117] UE NAS 5GSM entity notifies the application layer; and

[0118] ●UE NAS 5GMM entity notifies the application layer.

[0119] For any of the above options, during the service request process in which the UE sends a CPSR message including CIoT user data, if the UE receives a service accept or service reject message with a PDU session status IE such that the PDU session ID sent in the CPSR message (with CIoT user data) is set so that the message indicates that the PDU session is not active in the network, the UE may consider (or determine or conclude) that the CIoT user data was not successfully sent or transmitted. The UE may notify the upper layer of this failure of the CIoT user data transmission and optionally also provide the PDU session ID in question, which may be received in the service accept message or derived from the CPSR message sent earlier.

[0120] In one embodiment, the AMF sends a Service Accept message to the UE and includes the PDU Session Status IE and indicates that the PDU Session corresponding to the PDU Session ID (received in the CPSR message) is inactive.

[0121] In this option, when the identified scenario as described above occurs, the AMF may include the PDU Session Status IE in the SERVICE ACCEPT message. In addition, the AMF may set the bit corresponding to the PDU Session Identity (for which there is no PDU Session Routing Context) (i.e., the PSI bit) to indicate that the PDU Session is inactive. In other words, when sending the SERVICE ACCEPT message, the AMF may include the PDU Session Status IE and set the bit corresponding to the received PDU Session ID (e.g., from the CPSR message) to indicate that the PDU Session is inactive.

[0122] During the service request process in which the UE has sent a CPSR message with CIoT user data, if the UE receives a service accept message with a PDU session status IE such that the PDU session (identified by the PDU session ID) is indicated as inactive in the network (e.g., in the AMF), and the PDU session ID is the same as the PDU session ID that the UE has used in the CPSR message containing the CIoT user data, the UE determines that the CIoT user data has not been successfully sent. The UE notifies the 5GSM entity that the CIoT user data has not been successfully sent for the PDU session identifier. Note that the above behavior can be performed optionally after the UE has locally released the PDU session that has been identified as inactive in the network (via the PDU session status IE).

[0123] Optionally, if the UE has not received (optionally before receiving the service accept message) a DL NAS TRANSPORT message with a 5GMM cause value #90 and optionally CIoT user data that has not been forwarded, the UE acts as described above. Note that when the UE sends a PDU Session ID to the upper layer (as described above), the UE can determine the PDU Session ID as the PDU Session ID sent by the UE in a NAS message (i.e., a CPSR message or a UL NAS TRANSPORT message) (containing CIoT user data). Note that this can apply to any of the embodiments described herein.

[0124] Note that the UE sending an indication to upper layers may mean any of the following alternatives with respect to the above indication (optionally with the PDU Session ID in question):

[0125] The UE NAS 5GMM entity notifies the 5GSM entity, which in turn notifies the application layer;

[0126] UE NAS 5GSM entity notifies the application layer; and

[0127] ●UE NAS 5GMM entity notifies the application layer.

[0128] The following details apply to the UE regardless of the specific options selected above.

[0129] If the UE receives any NAS message (e.g. DL NAS TRANSPORT message, service accept message, service reject message, etc.) including a 5GMM cause value #90 "Payload not forwarded" and optionally a PDU session identifier, the UE may locally deactivate (or release) the PDU session identified by the PDU session identifier that has been received. Note that the actual local release of the PDU session may be performed by either the 5GMM entity or the 5GSM entity. In the case of a 5GSM entity, this behavior may be performed by the 5GSM entity if the 5GSM entity receives a cause value #90 from a 5GMM entity, optionally together with (at least one) PDU session identifier. Note that the above steps may optionally be applied if the content of the message that was not forwarded is a 5GSM message or CIoT user data, the main condition however being that the cause value may be associated with the PDU session identifier.

[0130] For any of the above options 1-5, if the AMF receives CIoT user data such that the PDU Session ID (for which the data is being sent) is inactive in the network, the AMF may discard the content of the message, or the AMF may discard the CIoT user data content. Note that this applies to any NAS message carrying CIoT user data, such as a CPSR message or a ULNAS TRANSPORT message. The following may be an example of the AMF behavior when the received NAS message is a CPSR message.

[0131] If a Control Plane SERVICE REQUEST message (or UL NAS TRANSPORT message) is received with CIoT user data for a PDU Session that is inactive in the network, the AMF may discard the CIoT user data. The AMF may send a SERVICE ACCEPT message and use the PDU SESSION STATUS IE to indicate that the PDU Session ID is inactive. Alternatively (optionally for the case where the AMF receives a UL NAS TRANSPORT), the AMF may send a DL NAS TRANSPORT or 5GMM STATUS message. The AMF may take the same action for either option or any NAS message received. For example, the AMF may apply similar behavior for the case where a SERVICE ACCEPT is received.

[0132] Alternatively, the AMF may send a service rejection message with a back-off (BO) timer, which may be any of the BO timers for DNN, S-NSSAI, or DNN and S-NSSAI congestion. For example, the sent timer may be related to T3396, T3584, or T3585. Alternatively, the timer may be related to 5GMM congestion (such as T3446) or congestion of CIoT data on the control plane (e.g., T3448) or service gap timer T3447 or any BO timer.

[0133] Note that this can apply to any of options 1-5 in this article.

[0134] All steps and actions described herein can be applied in any combination or order. For example, steps or actions from different options described herein can be combined and applied in any order.

[0135] In addition, all AMF behaviors already described in this document may also be applied to the MME as new MME behaviors, and vice versa. For example, for all detailed descriptions of the behaviors in this document, the AMF behaviors may be applicable to the MME behaviors, and vice versa. In doing so, all parameters or messages in a particular system may be the same or similar. For example, a PDU session ID in N1 mode (5GS) may be considered as an EPS bearer ID in S1 mode (EPS), and vice versa. A technician will easily understand the correlation and similarity between 5G and EPS and make any necessary adjustments.

[0136] Note that for the above options (in any one option or combination of options), the AMF behavior (or MME behavior) can be the same regardless of the message carrying the CIoT user data. For example, the AMF may receive a CPSR message or UL NAS TRANSPORT message with CIoT user data and for which the PDU Session ID is invalid or has no routing context. The AMF behavior can be any combination of the options in this document. Similarly, the UE behavior described for any option can be applied to any NAS message received and is therefore not tied to a specific NAS message received from the AMF. All steps can be applied in any order or combination for any NAS message received at the UE and / or network, and optionally for a PDU Session ID that is invalid (or inactive or inactive) or for which there is no routing context.

[0137] For any of the options above or in this document, or for any other use case not necessarily related to CIoT user data, if the AMF receives a NAS message (and optionally other data content, such as but not limited to CIoT user data) for a PDU session whose PDU session ID is inactive (or inactive), the AMF may also locally deactivate the PDU session context (i.e., set the context of the PDU session associated with that PDU session ID to inactive). The AMF may also notify the SMF of the release or deactivation of the PDU session. Therefore, this is applicable when the NAS message received by the AMF contains a 5GSM message or any other content destined for the SMF. The embodiments may apply to any NAS message received, or to whenever the AMF determines that the PDU session has no routing context.

[0138] Note that all details elaborated for the UE may be applied by the 5GMM entity or the 5GSM entity or both or any other entity in the UE or the entire NAS entity. All details apply to anything sent / received by the UE / AMF and are not limited to CIoT user data, but may also include, for example, 5GSM NAS messages, or any combination of CIoT user data and 5GSM NAS messages.

[0139] For all the above details, the AMF may also include the PDU Session Status IE (as described above) in the DL NAS TRANSPORT message. The UE behavior may be the same when this message is received together with the PDU Session Status IE. In other words, regardless of the type of message received (e.g., SERVICE ACCEPT or DL ​​NAS TRANSPORT message), the UE may process the PDU Session Status IE in the same manner as set forth herein or as described in 3GPP TS 24.501.

[0140] Regarding the problem of lack of MME's processing of CIoT user data with invalid EPS bearer identifiers, the following embodiments are applied.

[0141] If the MME receives an ESM DATATRANSPORT message (either as a standalone ESM message or included in a CPSR message), and the EPS bearer identity included in the ESM DATATRANSPORT message indicates an EPS bearer identity value that does not belong to any activated EPS bearer context in the MME (or is for an EPS bearer that does not belong to any activated EPS bearer context in the MME), the MME may act as follows, in any order or combination:

[0142] ●The MME may discard the contents of the CIoT USER DATA or ESM DATA TRANSPORT message;

[0143] The MME may abort the service request procedure or the transfer of user data via a control plane procedure (or ESM DATA TRANSPORT procedure); and

[0144] ● The MME may send an ESM STATUS message to the UE and include the ESM cause value #43 "Invalid EPS bearer identity". Note that the MME may still send a SERVICE ACCEPT message to the UE.

[0145] Note that an EPS bearer identity value that does not belong to any already activated EPS bearer context may mean that the state of the EPS bearer (associated with the EPS bearer identity in question) is BEARER CONTEXTINACTIVE.

[0146] During the service request process in which the UE sends (or has sent) an ESM DATA TRANSPORT message or a CPSR message including CIoT user data, if the UE receives an ESM STATUS message (optionally with a cause value #43), the UE may stop the associated timer, i.e., T3417. Optionally, the UE considers that the CIoT user data has not been successfully sent, and may also optionally provide an indication to the upper layer that the data has not been successfully sent.

[0147] Note that the UE sending the provided indication to upper layers may imply any of the following alternatives with respect to the above provided indication (optionally with the EPS bearer ID in question, e.g. the EPS bearer ID that the UE has included in the ESM DATA TRANSPORT message):

[0148] The UE NAS EMM entity notifies the ESM entity, which in turn notifies the application layer;

[0149] The UE NAS ESM entity notifies the application layer; and

[0150] ●UE NAS EMM entity notifies the application layer.

[0151] Note that the above details also apply to the case where the UE sends the ESM DATA TRANSPORT message in connected mode, i.e., the ESM message is not sent as part of the CPSR message. In this way, the same content may apply. For example, the following MME behavior is provided regardless of whether the ESM DATA TRANSPORT message is sent in the CPSR message.

[0152] If the EPS bearer identity provided in the ESM DATATRANSPORT message (received by the MME) indicates an EPS bearer identity value that does not belong to any already activated EPS bearer context, the MME may abort the transfer of user data via control plane procedures. The MME may then send an ESM STATUS message with ESM cause #43 "Invalid EPS bearer identity".

[0153] If the EPS bearer identity provided in the ESM DATATRANSPORT message (received by the MME) indicates an EPS bearer identity value that does not belong to any activated EPS bearer context, the MME may discard the content of the ESM DATATRANSPORT message. The MME may send an ESM STATUS message with ESM cause #43 "Invalid EPS bearer identity".

[0154] A similar solution is also provided for UEs that may receive ESM DATA TRANSPORT messages with invalid EPS bearer identities (or corresponding to EPS bearer contexts that are not active in the UE).

[0155] If the EPS bearer identity provided in the ESM DATA TRANSPORT message (received by the UE) indicates an EPS bearer identity value that does not belong to any already activated EPS bearer context, the UE may abort the transfer of user data via control plane procedures. The UE may then send an ESM STATUS message with ESM cause #43 "Invalid EPS bearer identity".

[0156] If the EPS bearer identity provided in the ESM DATA TRANSPORT message (received by the UE) indicates an EPS bearer identity value that does not belong to any already activated EPS bearer context, the UE may discard the content of the ESM DATA TRANSPORT message. The UE may then send an ESM STATUS message with ESM cause #43 "Invalid EPS bearer identity".

[0157] Note that for each detailed process or set of steps described herein, the steps or actions may be applied in any order or combination. This proposal also applies to S1 mode or N1 mode.

[0158] For the sake of completeness, Figure 1 A flow chart related to the first embodiment is shown from the perspective of the UE. At step S101, the UE sends a CPSR message with CIoT user data associated with a PDU session to the telecommunications network.

[0159] At step S102, the UE receives a service accept message from the telecommunication network indicating that the PDU session is inactive in the network.

[0160] At step S103, the UE verifies whether the PDU session has the same identity as that of the PDU session included in the CPSR message with the CIoT user data, and if so, the UE determines that the CIoT user data is not successfully sent to the telecommunication network.

[0161] Figure 2 A flow chart related to the second embodiment is shown from the perspective of the network. At step S201, the telecommunications network receives a CPSR message having CIoT user data associated with a PDU session from a UE.

[0162] At step S202, the telecommunications network discards the CIoT data.

[0163] At step S203, the telecommunication network sends a service accept message to the UE indicating that the PDU session is inactive in the network.

[0164] Figure 3 The internal configuration of a base station according to an embodiment of the present disclosure is shown.

[0165] like Figure 3 As shown, the base station according to the embodiment may include a transceiver 34, a memory 320 and a processor 330. The transceiver 34, the memory 320 and the processor 330 of the base station may operate according to the communication method of the above-mentioned base station. However, the components of the base station are not limited thereto. For example, the base station may include more or less components than the above-mentioned components. In addition, the processor 330, the transceiver 34 and the memory 320 may be implemented as a single chip. In addition, the processor 330 may include at least one processor.

[0166] The transceiver 34 refers to a base station receiver and a base station transmitter, and can send / receive signals to / from a terminal. The signals sent to or received from the terminal may include control information and data. The transceiver 34 may include an RF transmitter for up-converting and amplifying the frequency of the transmitted signal, and an RF receiver for amplifying the low noise and down-converting the frequency of the received signal. However, this is only an example of the transceiver 34, and the components of the transceiver 34 are not limited to the RF transmitter and the RF receiver.

[0167] In addition, the transceiver 34 may receive a signal through a wireless channel and output the signal to the processor 330 , and transmit a signal output from the processor 330 through a wireless channel.

[0168] The memory 320 may store programs and data required for the operation of the base station. In addition, the memory 320 may store control information or data included in a signal obtained by the base station. The memory 320 may be a storage medium such as a read-only memory (ROM), a random access memory (RAM), a hard disk, a CD-ROM, and a DVD, or a combination of storage media.

[0169] The processor 330 may control a series of processes so that the base station operates as described above. For example, the transceiver 34 may receive a data signal including a control signal sent by the terminal, and the processor 330 may determine the result of receiving the control signal and the data signal sent by the terminal. The processor may be referred to as a controller.

[0170] Figure 4 The internal structure of a terminal according to an embodiment of the present disclosure is shown.

[0171] like Figure 4 As shown, the terminal of the present disclosure may include a transceiver 44, a memory 44 and a processor 430. The transceiver 44, the memory 44 and the processor 430 of the terminal may operate according to the communication method of the above-mentioned terminal. However, the components of the terminal are not limited thereto. For example, the terminal may include more or less components than the above-mentioned components. In addition, the processor 430, the transceiver 44 and the memory 44 may be implemented as a single chip. In addition, the processor 430 may include at least one processor.

[0172] The transceiver 44 refers to a terminal receiver and a terminal transmitter, and can send / receive signals to / from a base station. The signals sent to or received from the base station may include control information and data. In this regard, the transceiver 44 may include an RF transmitter for up-converting and amplifying the frequency of the transmitted signal, and an RF receiver for amplifying the frequency of the low noise and down-converting the received signal. However, this is only an example of the transceiver 44, and the components of the transceiver 44 are not limited to the RF transmitter and the RF receiver.

[0173] In addition, the transceiver 44 may receive a signal through a wireless channel and output the signal to the processor 430 , and transmit a signal output from the processor 430 through a wireless channel.

[0174] The memory 44 may store programs and data required for the operation of the terminal. In addition, the memory 44 may store control information or data included in the signal obtained by the terminal. The memory 44 may be a storage medium such as ROM, RAM, hard disk, CD-ROM and DVD, or a combination of storage media.

[0175] The processor 430 may control a series of processes so that the terminal operates as described above. For example, the transceiver 44 may receive a data signal including a control signal, and the processor 430 may determine the result of receiving the data signal. The processor may be referred to as a controller.

[0176] When considered in conjunction with the following description and the accompanying drawings, these and other aspects of the embodiments herein will be better appreciated and understood. However, it should be understood that the following description, although indicating preferred embodiments and many specific details thereof, is provided in an illustrative and non-limiting manner. Without departing from the scope of the embodiments herein, many changes and modifications may be made within the scope of the embodiments herein, and the embodiments herein include all of these modifications.

[0177] The methods of the embodiments described in the claims or detailed description according to the present disclosure may be implemented in hardware, software, or a combination of hardware and software.

[0178] When the electrical structure and method are implemented in software, a computer-readable recording medium having one or more programs (software modules) recorded thereon may be provided. One or more programs recorded on the computer-readable recording medium are configured to be executable by one or more processors in an electronic device. One or more programs include instructions for executing the method of the embodiment described in the claims or detailed description according to the present disclosure.

[0179] The program (e.g., software module or software) may be stored in random access memory (RAM), non-volatile memory including flash memory, read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), magnetic disk storage device, compact disk-ROM (CD-ROM), digital versatile disk (DVD), another type of optical storage device, or magnetic tape cassette. Alternatively, the program may be stored in a memory system that includes a combination of some or all of the above memory devices. Furthermore, multiple memory devices may be included.

[0180] The program may also be stored in an attachable storage device that is accessible via a communication network such as the Internet, an intranet, a local area network (LAN), a wireless LAN (WLAN), or a storage area network (SAN), or a combination thereof. The storage device may be connected to an apparatus according to an embodiment of the present disclosure via an external port. Another storage device on the communication network may also be connected to an apparatus that performs an embodiment of the present disclosure.

[0181] In the above-mentioned specific embodiments of the present disclosure, the components included in the present disclosure are expressed in the singular or plural according to the specific embodiments presented in the present disclosure. However, for the convenience of description, the singular or plural expression is appropriately selected according to the presented situation, the present disclosure is not limited to the singular or plural components, and the components expressed in the plural may even be configured in the singular, or the components expressed in the singular may even be configured in the plural.

[0182] While the present disclosure has been shown and described with reference to various embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present disclosure as defined by the appended claims and their equivalents.

[0183] The foregoing description of specific embodiments will reveal the general nature of the embodiments herein very fully, so that others can easily modify and / or adjust such specific embodiments for various applications by applying current knowledge without departing from the general concepts, and therefore, such adjustments and modifications should and are intended to be understood as being within the meaning and scope of equivalents of the disclosed embodiments. It should be understood that the wording or terminology employed herein is for descriptive and not limiting purposes. Therefore, although the embodiments herein have been described according to preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced by modification within the spirit and scope of the embodiments as described herein.

[0184] Although the present disclosure has been described with various embodiments, various changes and modifications may be suggested to one skilled in the art. The present disclosure is intended to encompass such changes and modifications as fall within the scope of the appended claims.

[0185] The foregoing description of specific embodiments will reveal the general nature of the embodiments herein very fully, so that others can easily modify and / or adjust such specific embodiments for various applications by applying current knowledge without departing from the general concepts, and therefore, such adjustments and modifications should and are intended to be understood as being within the meaning and scope of equivalents of the disclosed embodiments. It should be understood that the wording or terminology employed herein is for descriptive and not limiting purposes. Therefore, although the embodiments herein have been described according to preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced by modification within the spirit and scope of the embodiments as described herein.

[0186] At least some of the example embodiments described herein can be constructed using special dedicated hardware in part or in whole. Terms such as "component", "module" or "unit" used herein may include but are not limited to hardware devices, such as circuits in discrete or integrated component form, field programmable gate arrays (FPGA) or application specific integrated circuits (ASIC), which perform certain tasks or provide associated functions. In some embodiments, the described element may be configured to reside on a tangible, persistent, addressable storage medium, and may be configured to execute on one or more processors. In some embodiments, these functional elements may include, for example, components, such as software components, object-oriented software components, class components and task components, processes, functions, attributes, procedures, subroutines, program code segments, drivers, firmware, microcodes, circuits, data, databases, data structures, tables, arrays and variables. Although example embodiments have been described with reference to components, modules and units discussed herein, such functional elements may be combined into fewer elements or separated into additional elements. Various combinations of optional features have been described herein, and it should be understood that the described features may be combined in any suitable combination. In particular, the features of any one exemplary embodiment may be appropriately combined with the features of any other embodiment, except where such combinations are mutually exclusive. Throughout the specification, the term "comprise" or "comprising" means including specified components but does not exclude the presence of other components.

[0187] Attention is paid to all papers and documents which are related to this application and which are filed concurrently with or before this specification and which are open to public inspection with this specification, and the contents of all these papers and documents are incorporated herein by reference.

[0188] All features disclosed in this specification (including any accompanying claims, abstract and drawings) and / or all steps of any method or process so disclosed may be combined in any combination, except combinations where at least some of such features and / or steps are mutually exclusive.

[0189] Unless expressly stated otherwise, each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose. Therefore, unless expressly stated otherwise, each feature disclosed is only an example of a general series of equivalent or similar features.

[0190] The present disclosure is not limited to the details of the foregoing embodiments. The present disclosure extends to any novel feature or any novel combination of features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel step or any novel combination of steps of any method or process disclosed in this manner.

[0191] Although the present disclosure has been described with various embodiments, various changes and modifications may be suggested to one skilled in the art. The present disclosure is intended to encompass such changes and modifications as fall within the scope of the appended claims.

Claims

1. A method for a user equipment UE, the method comprising: Sending a control plane service request CPSR message with cellular Internet of Things (CIoT) user data associated with a protocol data unit (PDU) session to a network entity; receiving a service accept message from a network entity indicating that the PDU session is inactive; verifying that the PDU session has the same identity as the identity of said PDU session included in the CPSR message with CIoT user data; and Based on determining that the PDU session has the same identifier as the identifier of the PDU session included in the CPSR message with CIoT user data, it is determined that the CIoT user data was not successfully sent to the network entity.

2. The method according to claim 1, wherein: The service acceptance message includes a PDU session status information element IE, and the PDU session status IE indicates that a PDU session corresponding to the identifier of the PDU session received in the CPSR message is in an inactive state.

3. A method of a network entity, the method comprising: receiving a control plane service request CPSR message having cellular Internet of Things (CIoT) user data associated with a protocol data unit (PDU) session from a user equipment (UE); When the PDU session is inactive, discarding CIoT data; and A service accept message is sent to the UE indicating that the PDU session is in an inactive state.

4. The method according to claim 3, further comprising: Receiving the CPSR message by an access and mobility management function, AMF, operatively coupled to the network entity; and The sending service accepts the message.

5. The method according to claim 4, wherein: The service acceptance message includes a PDU session status information element IE, and the PDU session status IE indicates that a PDU session corresponding to the identifier of the PDU session received in the CPSR message is in an inactive state.

6. A user equipment UE, the UE comprising: Memory; The transceiver is configured as: Sending a control plane service request CPSR message with cellular Internet of Things (CIoT) user data associated with a protocol data unit (PDU) session to a network entity; receiving a service accept message from a network entity indicating that the PDU session is inactive; and A processor operably coupled to the memory and the transceiver, the processor being configured to: verify that the PDU session has the same identity as the identity of the PDU session included in the CPSR message with the CIoT user data, and Based on determining that the PDU session has the same identifier as the identifier of the PDU session included in the CPSR message with CIoT user data, it is determined that the CIoT user data was not successfully sent to the network entity.

7. The UE according to claim 6, wherein: The service acceptance message includes a PDU session status information element IE, and the PDU session status IE indicates that a PDU session corresponding to the identifier of the PDU session received in the CPSR message is in an inactive state.

8. A network entity, comprising: Memory; A transceiver configured to receive a control plane service request CPSR message having cellular Internet of Things (CIoT) user data associated with a protocol data unit (PDU) session from a user equipment (UE); and a processor operably coupled to the memory and the transceiver, the processor being configured to discard CIoT data when the PDU session is inactive, The transceiver is further configured to send a service acceptance message to the UE indicating that the PDU session is in an inactive state.

9. The network entity according to claim 8, wherein: The transceiver is further configured to: Receiving the CPSR message by an access and mobility management function, AMF, operatively coupled to the network entity; and The sending service accepts the message.

10. The network entity according to claim 9, wherein: The service acceptance message includes a PDU session status information element IE, and the PDU session status IE indicates that a PDU session corresponding to the identifier of the PDU session received in the CPSR message is in an inactive state.

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