5G Session Management (5GSM) Process Enhancement Method and User Equipment

Abstract

A method and user equipment for enhancing a 5G session management process are provided. The method may include the following steps: receiving a first 5G session management (5GSM) message from a mobile communication network, the message including at least one mapped evolved packet system (EPS) bearer context for inter-system changes; and determining whether the at least one mapped EPS bearer context has one or more invalid or missing parameters; in response to the at least one mapped EPS bearer context having one or more invalid or missing parameters, sending a second 5GSM message to the mobile communication network to delete the at least one mapped EPS bearer context. According to the method and user equipment for enhancing a 5G session management process provided in the present application, the processing of the 5GSM process can be enhanced, and the UE operation and network operation related to the upcoming inter-system change can be improved.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. Provisional Application No. 62 / 907,925, filed on September 30, 2019, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present application relates generally to mobile communications, and more specifically, to an apparatus and method for 5G Session Management (5GSM) process enhancement. Background Art

[0004] In a typical mobile communication environment, a user equipment (UE) (also called a mobile station (MS)) (e.g., a mobile phone (also called a cellular phone or mobile phone) or a tablet personal computer (PC) with wireless communication capabilities) can communicate voice and / or data signals to one or more mobile communication networks. Wireless communication between UE and mobile communication network can be performed using various radio access technologies (Radio Access Technology, RAT), such as Global System for Mobile communications (GSM) technology, General Packet Radio Service (GPRS) technology, Enhanced Data rates for Global Evolution (EDGE) technology, Wideband Code Division Multiple Access (WCDMA) technology, Code Division Multiple Access 2000 (CDMA-2000) technology, Time Division-Synchronous Code Division Multiple Access (TD-SCDMA) technology, Worldwide Interoperability for Microwave Access (WiMAX) technology, Long Term Evolution (LTE) technology, Advanced LTE (LTE-Advanced, LTE-A) technology, etc. In particular, GSM / GPRS / EDGE technology is also called 2G cellular technology; WCDMA / CDMA-2000 / TD-SCDMA technology is also called 3G cellular technology; LTE / LTE-A / TD-LTE technology is also called 4G cellular technology.

[0005] These RATs have been used in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate at municipal, national, regional, and even global levels. An example of an emerging telecommunication standard is 5G New Radio (NR). 5G NR is a set of enhancements to the LTE mobile standard promulgated by the Third Generation Partnership Project (3GPP). It is designed to better support mobile broadband Internet access by improving spectrum efficiency, reducing costs, and improving services.

[0006] In 5G, a Protocol Data Unit (PDU) session defines the association between a UE and a data network that provides a PDU connection service. Each PDU session is identified by a PDU session ID and may include multiple Quality of Service (QoS) flows and QoS rules. QoS flows are the optimal granularity for QoS management to achieve more flexible QoS control. The concept of QoS flows in 5G is similar to the Evolved Packet System (EPS) bearer in 4G. According to 3GPP specifications compliant with 5G NR, interworking between the 5G System (5GS) and EPS can be supported, and the UE is allowed to perform an inter-system change procedure to switch from 5GS to EPS or from EPS to 5GS. Before the inter-system change from 5GS to EPS, the parameters of the PDU session should be correctly mapped to the parameters of the EPS bearer, and the mapped EPS bearer context should be provided to the UE through the 5GSM process.

[0007] However, in some cases, semantic errors may occur in the mapped EPS bearer context. As a result, after the inter-system change, the UE may not be able to successfully establish the corresponding EPS bearer context, which may cause service continuity failure. Summary of the invention

[0008] In order to solve the above problems, the present application proposes to enable the UE to check the mapped EPS bearer contexts to see if there are semantic errors in each mapped EPS bearer context. In particular, semantic errors of the generated mapped EPS bearer contexts with invalid or missing parameters should be discovered for appropriate processing.

[0009] In a first aspect of the present application, a method is provided, which is performed by a UE that is communicatively connected to a mobile communication network. The method comprises the following steps: receiving a first 5GSM message including at least one mapped EPS bearer context for inter-system change from the mobile communication network; and determining whether at least one mapped EPS bearer context has one or more invalid or missing parameters; in response to at least one mapped EPS bearer context having one or more invalid or missing parameters, sending a second 5GSM message to the mobile communication network to delete at least one mapped EPS bearer context.

[0010] In another embodiment of the first aspect, the first 5GSM message is a PDU SESSIONMODIFICATION COMMAND message or a PDU SESSION ESTABLISHMENT ACCEPT message.

[0011] In another embodiment of the first aspect, when the UE is in N1 mode, a first 5GSM message is received, and the inter-system change is from N1 mode to S1 mode.

[0012] In another embodiment of the first aspect, the mapped EPS bearer context includes an operation code indicating creation of a new EPS bearer or modification of an existing EPS bearer.

[0013] In another embodiment of the first aspect, the invalid or missing parameter is a mandatory parameter for activating a dedicated EPS bearer context for inter-system change.

[0014] In another embodiment of the first aspect, the mandatory parameters include a plurality of EPS Quality of Service (QoS) parameters and a plurality of Traffic Flow Template (TFT) parameters for a dedicated EPS bearer context.

[0015] In another embodiment of the first aspect, the invalid or missing parameter is a mandatory parameter for activating a default EPS bearer context for the inter-system change.

[0016] In another embodiment of the first aspect, the mandatory parameters include a plurality of EPS QoS parameters for a default EPS bearer context.

[0017] In another embodiment of the first aspect, each invalid parameter is a mandatory parameter that has a reserved value, a decoding error, a length error, a syntactical error, or a semantic error, or is empty.

[0018] In another embodiment of the first aspect, the second 5GSM message is a PDU SESSIONMODIFICATION REQUEST message including a 5GSM cause indicating an invalid mapped EPS bearer identity.

[0019] In a second aspect of the present application, a UE including a wireless transceiver and a controller is provided. The wireless transceiver is configured to perform wireless transmission and reception with a mobile communication network. The controller is coupled to the wireless transceiver and is configured to receive a first 5GSM message including at least one mapped EPS bearer context for inter-system change from the mobile communication network via the wireless transceiver, and determine whether the at least one mapped EPS bearer context has one or more invalid or missing parameters. The controller also sends a second 5GSM message to the mobile communication network via the wireless transceiver in response to at least one mapped EPS bearer context having one or more invalid or missing parameters to delete at least one mapped EPS bearer context.

[0020] In another embodiment of the second aspect, the first 5GSM message is a PDU session modification command message or a PDU session establishment accept message.

[0021] In another embodiment of the second aspect, when the UE is in N1 mode, a first 5GSM message is received, and the inter-system change is from N1 mode to S1 mode.

[0022] In another embodiment of the second aspect, the mapped EPS bearer context includes an operation code indicating creation of a new EPS bearer or modification of an existing EPS bearer.

[0023] In another embodiment of the second aspect, the invalid or missing parameter is a mandatory parameter for activating a dedicated EPS bearer context for inter-system change.

[0024] In another embodiment of the second aspect, the mandatory parameters include EPS QoS parameters and TFT parameters for the dedicated EPS bearer context.

[0025] In another embodiment of the second aspect, the invalid or missing parameter is a mandatory parameter for activating a default EPS bearer context for the inter-system change.

[0026] In another embodiment of the second aspect, the mandatory parameters include a plurality of EPSQoS parameters for a default EPS bearer context.

[0027] In another embodiment of the second aspect, each invalid parameter is a mandatory parameter that has a reserved value, a decoding error, a length error, a syntax error, or a semantic error, or is empty.

[0028] In another embodiment of the second aspect, the second 5GSM message is a PDU SESSION MODIFY REQUEST message including a 5GSM cause indicating an invalid mapped EPS bearer identity.

[0029] According to the method and user equipment for enhancing the 5G session management process provided in the present application, the processing of the 5GSM process can be enhanced and the UE operation and network operation related to the upcoming inter-system changes can be improved.

[0030] After reading the following description of specific embodiments of the method and UE for 5GSM process enhancement, other aspects and features of the present application will become apparent to one of ordinary skill in the art. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The present application may be more fully understood by reading the following detailed description and examples with reference to the accompanying drawings, in which:

[0032] Figure 1 is a block diagram of a mobile communication environment according to an embodiment of the present application;

[0033] Figure 2 is a block diagram showing a UE 110 according to an embodiment of the present application;

[0034] Figure 3 is a flow chart showing a method for 5GSM process enhancement according to an embodiment of the present application;

[0035] Figure 4 is a message sequence chart showing an enhancement of a network requested PDU session modification procedure according to an embodiment of the present application; and

[0036] Figure 5 Detailed description of the invention is given in the following figure: FIG. 1 is a message sequence chart showing an enhancement of a UE-requested PDU session establishment procedure according to an embodiment of the present application. DETAILED DESCRIPTION

[0037] The following description is made to illustrate the general principles of the present application and should not be understood in a limiting sense. It should be understood that the embodiments can be implemented in software, hardware, firmware or any combination thereof. When the terms "comprise", "comprising", "include" and / or "including" are used in this application, the presence of the features, integers, steps, operations, elements and / or components is specified, but the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof is not excluded.

[0038] Figure 1 is a block diagram of a mobile communication environment according to an embodiment of the present application.

[0039] like Figure 1 As shown, the mobile communication environment 100 may include a UE 110 and two mobile communication networks 120 and 130, wherein the UE 110 may selectively connect to one or both of the mobile communication networks 120 and 130 for obtaining mobile services.

[0040] UE 110 may be a feature phone, a smart phone, a tablet personal computer (PC), a laptop computer, or any wireless communication device supporting the RAT utilized by mobile communication network 120 and mobile communication network 130 .

[0041] The mobile communication network 120 may include an access network 121 and a core network 122, and the mobile communication network 130 may include an access network 131 and a core network 132. The access network 121 and the access network 131 are responsible for processing radio signals, terminating radio protocols, and connecting the UE 110 to the core network 122 and the core network 132, respectively. The core network 122 and the core network 132 are responsible for performing mobility management, network-side authentication, and interfacing with a public / external network (e.g., the Internet). The access network 121 and the access network 131 and the core network 122 and the core network 132 may each include one or more network nodes for performing the functions.

[0042] For example, the mobile communication network 120 may be a 5G NR network, and the access network 121 and the core network 122 may be a Next Generation Radio Access Network (NG-RAN) and a Next Generation Core Network (NG-CN).

[0043] The NG-RAN may include one or more cell sites, such as next generation NodeBs (gNBs) supporting high frequency bands (e.g., above 24 GHz), and each gNB may further include one or more Transmission Reception Points (TRPs). Some gNB functions may be distributed across different TRPs, while other functions may be centralized, retaining the flexibility and scope for specific deployments to meet the requirements of specific situations.

[0044] NG-CN is typically composed of various network functions, including Access and Mobility Function (AMF), Session Management Function (SMF), Policy Control Function (PCF), Application Function (AF), Authentication Server Function (AUSF), User Plane Function (UPF) and User Data Management (UDM), each of which can be implemented as an element on dedicated hardware, as a software instance running on dedicated hardware, or as a virtualized function instantiated on an appropriate platform (e.g., cloud infrastructure).

[0045] AMF provides UE-based authentication, authorization, mobility management, etc. SMF is responsible for session management and assigns Internet Protocol (IP) addresses to UEs. SMF also selects and controls UPF for data transmission. If the UE has multiple sessions, different SMFs can be assigned to each session to manage them separately, and different functions may be provided for each session. AF provides information about packet flows to the PCF responsible for policy control to support QoS. Based on this information, the PCF determines policies on mobility and session management to enable the normal operation of the AMF and SMF. The AUSF stores data for UE authentication, while the UDM stores UE subscription data.

[0046] For example, the mobile communication network 130 may be a 4G LTE network, and the access network 131 and the core network 132 may be an Evolved-Universal Terrestrial Radio Access Network (E-UTRAN) and an Evolved Packet Core (EPC), respectively.

[0047] The E-UTRAN may include at least an evolved NodeB (eNB) (e.g., a macro eNB, a femto eNB, or a pico eNB). The EPC may include a Home Subscriber Server (HSS), a Mobility Management Entity (MME), a Serving Gateway (S-GW), and a Packet Data Network Gateway (PDN-GW / P-GW).

[0048] The HSS is a central database that contains user-related and subscription-related information. The functions of the HSS include functions such as mobility management, call and session establishment support, user authentication and access authorization.

[0049] The MME is responsible for idle mode UE paging and marking procedures including retransmissions. The MME is involved in the bearer activation / deactivation process and is also responsible for selecting the S-GW for the UE 110 at the time of initial connection and at intra-LTE handover including core network (CN) node relocation. The MME is also responsible for user authentication (by interacting with the HSS) and generating / allocating temporary identities to the UE 110. The MME is also the termination point in the network for ciphering / integrity protection of Non Access Stratum (NAS) signaling and handles security key management.

[0050] The S-GW is responsible for routing and forwarding user data packets, while also acting as the mobility anchor point for the user plane during inter-eNB handovers and as the mobility anchor point between LTE and other 3GPP technologies.

[0051] The P-GW provides connectivity from the UE 110 to external PDNs by acting as the egress and ingress point for traffic of the UE 110. The PGW also provides policy enforcement, packet filtering for each user, charging support, lawful interception, and packet screening.

[0052] It should be understood that Figure 1 The mobile communication environment 100 described in the embodiment is for illustration purposes only and is not intended to limit the scope of the present application.

[0053] Figure 2 is a block diagram illustrating a UE 110 according to an embodiment of the present application.

[0054] like Figure 2As shown, UE 110 may include a wireless transceiver 10 , a controller 20 , a storage device 30 , a display device 40 , and an input / output (I / O) device 50 .

[0055] The wireless transceiver 10 is configured to perform wireless transmission and reception with the mobile communication network 120 and / or the mobile communication network 130 .

[0056] Specifically, the wireless transceiver 10 may include a baseband processing device 11, a radio frequency (RF) device 12, and an antenna 13, wherein the antenna 13 may include an antenna array for beamforming.

[0057] The baseband processing device 11 is configured to perform baseband signal processing and control communication between one or more subscriber identity cards (not shown) and the RF device 12. The baseband processing device 11 may include multiple hardware components to perform baseband signal processing, including analog-to-digital conversion (ADC) / digital-to-analog conversion (DAC), gain adjustment, modulation / demodulation, encoding / decoding, etc.

[0058] The RF device 12 can receive an RF wireless signal via an antenna 13, convert the received RF wireless signal into a baseband signal processed by the baseband processing device 11, or receive a baseband signal from the baseband processing device 11 and convert it, convert the received baseband signal into an RF wireless signal, and then send the RF wireless signal through the antenna 13. The RF device 12 may also include multiple hardware devices to perform radio frequency conversion. For example, the RF device 12 may include a mixer to multiply the baseband signal with a carrier oscillating in the radio frequency of the supported RAT, where the radio frequency can be any radio frequency used in 5G NR technology (for example, millimeter wave is 30 GHz to 300 GHz), or it can be 900 MHz, 2100 MHz or 2.6 GHz used in 4G LTE / LTE-A / TD-LTE technology, or other radio frequencies, depending on the RAT used.

[0059] The controller 20 can be a general-purpose processor, a micro control unit (MCU), an application processor, a digital signal processor (DSP), a graphics processing unit (GPU), a holographic processing unit (HPU), a neural processing unit (NPU), etc., which includes various circuits for providing data processing and computing, controlling the wireless transceiver 10 to wirelessly communicate with the mobile communication network 120 and / or the mobile communication network 130, storing data in the storage device 30 and retrieving data (e.g., program code) from the storage device 30, sending a series of frame data (e.g., representing text messages, graphics, images, etc.) to the display device 40, and receiving user input or output signals through the I / O device 50.

[0060] In particular, the controller 20 coordinates the aforementioned operations of the wireless transceiver 10 , the storage device 30 , the display device 40 , and the I / O device 50 to execute the method of the present application.

[0061] In another embodiment, the controller 20 may be incorporated into the baseband processing device 11 to function as a baseband processor.

[0062] As will be appreciated by those skilled in the art, the circuitry of the controller 20 will typically include transistors configured to control the operation of the circuitry in accordance with the functions and operations described herein. As will be further appreciated, the specific structure or interconnection of the transistors will typically be determined by a compiler such as a register transfer language (RTL) compiler. The RTL compiler can be operated by a processor on a script that is very similar to assembly language code to compile the script into a form for final circuit layout or manufacturing. In fact, RTL is well known for its role and use in facilitating the design of electronic and digital systems.

[0063] The storage device 30 can be a non-temporary machine-readable storage medium, including a memory such as FLASH memory or non-volatile random access memory (NVRAM), or a magnetic storage device such as a hard disk, a disk, a tape, an optical disk, or any combination thereof for storing data, instructions, and / or program codes of applications, communication protocols, and / or methods of the present application.

[0064] The display device 40 may be a liquid crystal display (LCD), a light-emitting diode (LED) display, an organic LED (OLED) display, or an electronic paper display (EPD) to provide a display function. Optionally, the display device 40 may further include one or more touch sensors arranged on or below it for sensing a touch, contact, or proximity of an object such as a finger or a pen.

[0065] The I / O device 50 may include one or more buttons, keyboards, mice, touch pads, cameras, microphones and / or speakers, etc., to serve as a man-machine interface (MMI) for interaction with users.

[0066] It should be understood that Figure 2 The components described in the embodiments are for illustrative purposes only and are not intended to limit the scope of the present application.

[0067] For example, the UE may include more components, such as a power source, a global positioning system (GPS) device, and / or another wireless transceiver. The power source may be a mobile / replaceable battery that powers all other components of the UE 110. The GPS device may provide location information of the UE 110 for use by certain location-based services or applications. In the case where the UE 110 supports dual registration to 5GS and EPS, another wireless transceiver may be used for wireless transceiver with one of the mobile communication network 120 and the mobile communication network 130, and the wireless transceiver 10 may be used for wireless transceiver with the other of the mobile communication network 120 and the mobile communication network 130. Optionally, the UE may include fewer components. For example, the UE may not include a display device 40 and / or an I / O device 50.

[0068] Figure 3 is a flowchart illustrating a method for 5GSM process enhancement according to an embodiment of the present application.

[0069] In this embodiment, the method for 5GSM process enhancement may be applied to and executed by a UE (e.g., UE 110) that is wirelessly and communicatively connected to a mobile communication network (e.g., mobile communication network 120).

[0070] First, the UE receives a first 5GSM message including at least one mapped EPS bearer context for inter-system change from a mobile communication network (step S310).

[0071] Specifically, when the UE is in N1 mode, the first 5GSM message is received, and the inter-system change is from N1 mode to S1 mode. N1 mode refers to a mode in which the UE is allowed to access the 5G core network via a 5G access network, while S1 mode refers to a mode in which the UE is allowed to access the 4G core network via a 4G access network.

[0072] In one embodiment, the first 5 GSM message may be received during a network requested PDU session modification procedure, and the first 5 GSM message may be a PDU session modification command message.

[0073] In another embodiment, the first 5 GSM message may be received during a UE-requested PDU session establishment procedure, and the first 5 GSM message may be a PDU session establishment accept message.

[0074] After step S310, the UE determines whether at least one mapped EPS bearer context has one or more invalid or missing parameters (step S320).

[0075] Specifically, the mapped EPS bearer context includes an operation code indicating "create a new EPS bearer" or "modify an existing EPS bearer".

[0076] In one embodiment, the invalid or missing parameters may be mandatory parameters for activating a dedicated EPS bearer context for inter-system change. For example, the mandatory parameters may include a plurality of EPS QoS parameters and a plurality of TFT parameters for a dedicated EPS bearer context.

[0077] In another embodiment, the invalid or missing parameters may be mandatory parameters for activating a default EPS bearer context for inter-system change. For example, the mandatory parameters may include a plurality of EPS QoS parameters for the default EPS bearer context.

[0078] If any of the multiple EPS QoS parameters and the multiple TFT parameters has a reserved value, a decoding error, a length error, a syntax error, or a semantic error, or is empty, it can be determined that the mapped EPS bearer context contains invalid parameters. For the definition of the reserved value, decoding error, length error, syntax error, or semantic error of the above parameters, reference can be made to the 3GPP specification that complies with 5G NR.

[0079] After step S320, the UE sends a second 5GSM message to the mobile communication network to delete at least one mapped EPS bearer context in response to at least one mapped EPS bearer context having one or more invalid or missing parameters (step S330), and the method ends.

[0080] Specifically, the second 5GSM message is a PDU Session Modification Request message, which includes a 5GSM cause indicating "Invalid mapped EPS bearer identity" (e.g., 5GSM cause #85).

[0081] Figure 4 is an enhanced message sequence chart showing a network requested PDU session modification procedure according to an embodiment of the present application.

[0082] In step S410, UE 110 receives a PDU session modification command message including multiple mapped EPS bearer contexts from mobile communication network 120 (e.g., 5GS).

[0083] In step S420, UE 110 checks semantic errors of each mapped EPS bearer context. Specifically, a specific semantic error is found in one of the multiple mapped EPS bearer contexts, wherein the specific semantic error refers to an operation code indicating "create new EPS bearer" or "modify existing EPS bearer", and the obtained multiple mapped EPS bearer contexts have invalid or missing mandatory parameters (for example, multiple mapped EPS QoS parameters or multiple TFTs of a dedicated EPS bearer context).

[0084] In step S430 , UE 110 sends a PDU session modification complete message to mobile communication network 120 .

[0085] In step S440, when a specific semantic error is found in the mapped EPS bearer context, UE 110 initiates the PDU session modification procedure by sending a PDU session modification request message to delete the mapped EPS bearer context with 5GSM cause #85 "Invalid mapped EPS bearer identity".

[0086] In step S450, UE 110 receives a PDU Session Modification Command message from mobile communication network 120. Specifically, the PDU Session Modification Command message includes the mapped EPS bearer context to be deleted.

[0087] In step S460, UE 110 deletes the mapped EPS bearer context according to the PDU Session Modification Command message.

[0088] In step S470 , UE 110 sends a PDU session modification complete message to mobile communication network 120 .

[0089] Figure 5 Detailed description of the invention is given in the following figure: FIG. 1 is a message sequence chart showing an enhancement of a UE-requested PDU session establishment procedure according to an embodiment of the present application.

[0090] In step S510, UE 110 sends a PDU session establishment request message to the mobile communication network 120 (e.g., 5GS).

[0091] In step S520 , UE 110 receives a PDU session establishment accept message including a plurality of mapped EPS bearer contexts from mobile communication network 120 .

[0092] In step S530, UE 110 checks semantic errors of each mapped EPS bearer context. Specifically, a specific semantic error is found in one of the mapped EPS bearer contexts, wherein the specific semantic error refers to an operation code indicating "create new EPS bearer" or "modify existing EPS bearer", and the resulting mapped EPS bearer context has invalid or missing mandatory parameters (e.g., multiple EPS QoS parameters or multiple TFTs mapped for a dedicated EPS bearer context).

[0093] In step S540, when a specific semantic error is found in the mapped EPS bearer context, UE 110 initiates the PDU session modification procedure by sending a PDU session modification request message to delete the mapped EPS bearer context with 5GSM cause #85 "Invalid mapped EPS bearer identity".

[0094] In step S550, UE 110 receives a PDU Session Modification Command message from mobile communication network 120. Specifically, the PDU Session Modification Command message includes a mapped EPS bearer context to be deleted.

[0095] In step S560, UE 110 deletes the mapped EPS bearer context according to the PDU Session Modification Command message.

[0096] In step S570 , UE 110 sends a PDU session modification complete message to mobile communication network 120 .

[0097] In view of the foregoing embodiments, it will be appreciated that the present application enhances the processing of 5GSM procedures (e.g., network-requested PDU session modification procedures and UE-requested PDU session establishment procedures) by enabling the UE to thoroughly check the semantic errors of the mapped EPS bearer context. In particular, semantic errors of the resulting mapped EPS bearer context with invalid or missing parameters are thus discovered for appropriate processing. Advantageously, UE operations and network operations related to upcoming inter-system changes can be improved.

[0098] Although the present application has been described by way of example and according to preferred embodiments, it should be understood that the present application is not limited thereto. Without departing from the scope and spirit of the present application, those skilled in the art can still make various changes and modifications. Therefore, the scope of the present application should be limited and protected by the attached claims and their equivalents.

Claims

1. A method for enhancing a 5G session management process, performed by a user equipment communicatively connected to a mobile communication network, the method comprising: receiving, from the mobile communications network, a first 5G session management message including at least one mapped evolved packet system bearer context for inter-system change; determining that there is a semantic error in the at least one mapped evolved packet system bearer context; as well as In response to the semantic error being that the mapped evolved packet system bearer context includes an operation code indicating creation of a new evolved packet system bearer or modification of an existing evolved packet system bearer and the resulting mapped evolved packet system bearer context has invalid or missing mandatory parameters, a second 5G session management message is sent to the mobile communication network to delete the at least one mapped evolved packet system bearer context.

2. The method according to claim 1, characterized in that The first 5G session management message is a protocol data unit session modification command message or a protocol data unit session establishment acceptance message.

3. The method according to claim 1, characterized in that The first 5G session management message is received when the user equipment is in N1 mode, and the inter-system change is from the N1 mode to the S1 mode.

4. The method according to claim 1, characterized in that: The invalid or missing parameter is a mandatory parameter for activating a dedicated evolved packet system bearer context for the inter-system change, or the invalid or missing parameter is a mandatory parameter for activating a default evolved packet system bearer context for the inter-system change.

5. The method according to claim 4, characterized in that The mandatory parameters include a plurality of EPS quality of service parameters and a plurality of service flow template parameters for the dedicated EPS bearer context, or the mandatory parameters include a plurality of EPS quality of service parameters for the default EPS bearer context.

6. The method according to claim 1, characterized in that Each of the invalid parameters is a mandatory parameter that has a reserved value, a decoding error, a length error, a syntax error, or a semantic error, or is empty.

7. The method according to claim 1, characterized in that The second 5G session management message is a protocol data unit session modification request message, which includes a 5G session management cause indicating an invalid mapped evolved packet system bearer identity.

8. A user equipment for 5G session management process enhancement, comprising: A wireless transceiver configured to perform wireless transmission and reception with a mobile communication network; as well as A controller is coupled to the wireless transceiver and configured to receive a first 5G session management message from the mobile communication network via the wireless transceiver, the message including at least one mapped evolved packet system bearer context for inter-system change, determine that there is a semantic error in the at least one mapped evolved packet system bearer context, and in response to the semantic error being that the mapped evolved packet system bearer context includes an operation code indicating the creation of a new evolved packet system bearer or the modification of an existing evolved packet system bearer and the resulting mapped evolved packet system bearer context has an invalid or missing mandatory parameter, send a second 5G session management message to the mobile communication network via the wireless transceiver to delete the at least one mapped evolved packet system bearer context.

9. The user equipment according to claim 8, characterized in that The first 5G session management message is a protocol data unit session modification command message or a protocol data unit session establishment acceptance message.

10. The user equipment according to claim 8, characterized in that The first 5G session management message is received when the user equipment is in N1 mode, and the inter-system change is from the N1 mode to the S1 mode.

11. The user equipment according to claim 8, characterized in that The invalid or missing parameter is a mandatory parameter for activating a dedicated evolved packet system bearer context for the inter-system change, or the invalid or missing parameter is a mandatory parameter for activating a default evolved packet system bearer context for the inter-system change.

12. The user equipment according to claim 11, characterized in that The mandatory parameters include a plurality of EPS quality of service parameters and a plurality of service flow template parameters for the dedicated EPS bearer context, or the mandatory parameters include a plurality of EPS quality of service parameters for the default EPS bearer context.

13. The user equipment according to claim 8, characterized in that Each of the invalid parameters is a mandatory parameter that has a reserved value, a decoding error, a length error, a syntax error, or a semantic error, or is empty.

14. The user equipment according to claim 8, characterized in that The second 5G session management message is a protocol data unit session modification request message, which includes a 5G session management cause indicating an invalid mapped evolved packet system bearer identity.

15. A non-transitory machine-readable storage medium comprising program instructions and data, which, when executed by a controller of a user equipment enhanced by a 5G session management process, causes the user equipment to perform the following operations: receiving, from the mobile communications network, a first 5G session management message including at least one mapped evolved packet system bearer context for inter-system change; determining that there is a semantic error in the at least one mapped evolved packet system bearer context; and In response to the semantic error being that the mapped evolved packet system bearer context includes an operation code indicating creation of a new evolved packet system bearer or modification of an existing evolved packet system bearer and the resulting mapped evolved packet system bearer context has invalid or missing mandatory parameters, a second 5G session management message is sent to the mobile communication network to delete the at least one mapped evolved packet system bearer context.

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