CN117998571A - Deregistration and EMM parameter handling taking into account access type - Google Patents

Abstract

De-registration of the access type and EMM parameter handling are considered. The present invention proposes a method of handling deregistration of 3GPP and EPS Mobility Management (EMM) parameters when a UE receives a deregistration request message via non-3 GPP. There is an access type in the deregistration type IE in the deregistration request message. In one novel aspect, the UE processes EMM parameters of the deregistration procedure according to the access type in the received deregistration type IE. Upon receiving the de-registration request message, if the de-registration request is for 3GPP access or for 3GPP access and non-3 GPP access, the UE performs local release of PDU sessions over 3GPP access and non-3 GPP access (if any). Based on the 5GMM reason, the UE also processes corresponding EMM parameters including EMM status, EPS update status, 4G-GUTI, last accessed registration TAI, TAI list, eKSI, and attach attempt counter.

Description

Deregistration and EMM parameter handling taking into account access type

Technical Field

The disclosed embodiments relate generally to wireless communications and, more particularly, to de-registration and EPS mobility management (EPS mobility management, EMM) parameter handling when a UE receives a de-registration request message via non-3 GPP access.

Background

Third generation partnership project (Third generation partnership project,3 GPP) and 5G New Radio (NR) mobile telecommunications systems provide high data rates, lower latency, and improved system performance. In 3GPP NR, a 5G terrestrial New Radio (NR) access network (including a plurality of base stations, e.g., next Generation Node-bs (gnbs)) communicates with a plurality of mobile stations called User Equipments (UEs). Orthogonal frequency division multiple access (Orthogonal Frequency Division Multiple Access, OFDMA) has been selected for NR downlink radio access schemes due to its robustness to multipath fading, higher spectral efficiency and bandwidth scalability. Multiple access in the downlink is achieved by assigning different subbands (i.e., groups of subcarriers, denoted Resource Blocks (RBs)) of the system bandwidth to individual users based on their existing channel conditions.

Operators are seeking to balance data traffic between mobile cellular networks and non-3 GPP accesses in a manner that is transparent to users and reduces mobile network congestion. In 5GS, UEs that can connect to both 3GPP access and non-3 GPP access (using 3GPP NAS signaling) (thus 5GS can exploit these multiple access to improve user experience) optimize traffic distribution across the various accesses. Thus, the UE may register with both 3GPP and non-3 GPP and establish a PDU session or MA PDU session over both 3GPP and non-3 GPP sessions.

If the UE registers with both the 3GPP access and the non-3 GPP access, the UE may receive messages from both accesses. For example, when the UE receives the deregistration request message from the network, the deregistration may be obtained through the 3GPP access when the UE receives the deregistration request message via the non-3 GPP access. In the current specification, the cause processing is determined by the access type of the received message. If a message is received via 3GPP access and the UE is operating in single registration mode, then in case a DETACH REQUEST (DETACH REQUEST) is received with the same value and with the DETACH type EMM cause set to "do not need reattach", the UE processes the EMM parameter as specified in 3GPP TS 24.301, or the UE sets the EPS update status to not update EU2, resets the attach attempt counter, and enters the status EMM deregistration. However, if a message is received via a non-3 GPP access, some processing for the 3GPP access will be missed. If the UE receives a de-registration request over a non-3 GPP access, the UE may not process the EMM parameters, including EMM status, EPS update status, 4G-GUTI, TAI list, and eKSI.

A solution is sought.

Disclosure of Invention

The present invention proposes a method of handling deregistration and EPS Mobility Management (EMM) parameters of 3GPP when a UE receives a deregistration request message containing an access type. There is an access type in the deregistration type IE in the deregistration request message. In one novel aspect, the UE processes EMM parameters of the deregistration procedure according to the access type in the received deregistration type IE. Upon receiving the de-registration request message over the non-3 GPP access, if the de-registration request is for the 3GPP access or for both the 3GPP access and the non-3 GPP access, the UE performs local release of the PDU session over the 3GPP access and the non-3 GPP access (if any). Based on the 5GMM reason, the UE also processes corresponding EMM parameters including EMM status, EPS update status, 4G-GUTI, last accessed registration TAI, TAI list, eKSI, and attach attempt counter. Upon receipt of the de-registration request message over the 3GPP access, if the de-registration request is for a non-3 GPP access, the UE performs a local release of PDU sessions for the non-3 GPP access (if any) and skips processing EMM parameters.

In one embodiment, a UE maintains a set of EPS Mobility Management (EMM) parameters, wherein the UE registers with a 5G network over 3GPP access. The UE is also registered with the 5G network through non-3 GPP access. The UE later receives a deregistration request message from the 5G network over a non-3 GPP access, wherein the message carries a deregistration type Information Element (IE) including an access type and a 5GMM cause value. Then, the UE performs de-registration from the 5g 3GPP and processes EMM parameters based on the access type and the 5GMM cause value, wherein the message is received through the non-3 GPP access and the access type indicates the 3GPP access or indicates both the 3GPP access and the non-3 GPP access.

Other embodiments and advantages are described in the detailed description that follows. This summary is not intended to limit the invention. The invention is defined by the claims.

Drawings

The accompanying drawings illustrate embodiments of the invention in which like reference numerals refer to like parts.

Fig. 1 illustrates an exemplary 5G network and method of handling deregistration and EPS Mobility Management (EMM) parameters when a UE receives a deregistration request message via a non-3 GPP access, according to one novel aspect.

Fig. 2 illustrates a simplified block diagram of a User Equipment (UE) and a network entity according to an embodiment of the present invention.

Fig. 3 illustrates an example of a deregistration type IE carrying an access type, and the UE processes the deregistration procedure and EMM parameters based on the access type.

Fig. 4 illustrates an example of a 5GMM cause value carried by a deregistration request message, and the UE processes the deregistration procedure and EMM parameters based on the 5GMM cause value.

Fig. 5 illustrates one embodiment of a sequence flow between a UE and a 5G network for a de-registration procedure in accordance with one novel aspect.

Fig. 6 is a flow chart of a method of handling deregistration and EPS Mobility Management (EMM) parameters of 3GPP when a UE receives a deregistration request message via non-3 GPP according to one novel aspect of the present invention.

Detailed Description

Reference will now be made in detail to some embodiments of the invention, examples of which are illustrated in the accompanying drawings.

Fig. 1 illustrates an exemplary 5G network and method of handling deregistration and EPS Mobility Management (EMM) parameters when a UE receives a deregistration request message via a non-3GPP access, according to one novel aspect. The 5G New Radio (NR) network 100 includes User Equipment (UE) 101, 3GPP access 102 (e.g., 3GPP radio access network (radio access network, RAN)), non-3GPP access 103 (e.g., non-3GPP AN), access and mobility management functions (ACCESS AND mobility management function, AMF) 110, session management functions (session management function, SMF) 111, non-3GPP interworking functions (non-3GPP interworking function,N3IWF) 112, user plane functions (user plane function, UPF) 113, and 5G core,5 gc) data network 120. The AMF 110 communicates with base stations in the 3GPP access 102, SMF 111, and UPF 113 for access and mobility management of wireless access devices in the 5G network 100. The SMF 111 is primarily responsible for interacting with the decoupled data plane, creating, updating and removing PDU sessions and managing session context with the UPF 113. The N3IWF 112 interfaces to the 5G core network control plane function and is responsible for routing messages outside the 5G AN. Note that an intersystem change may be performed between 5g 3gpp (N1 mode) and 4g 3gpp (S1 mode).

In an Access Stratum (AS) layer, the RAN provides radio Access to the UE 101 via a radio Access technology (radio Access technology, RAT). In a Non-Access Stratum (NAS) layer, AMFs 110 and SMFs 111 communicate with RANs and 5 GCs for Access and mobility management and PDU session management of wireless Access devices in the 5G network 100. The 3GPP access 102 can include a base station (gNB or eNB) that provides radio access for the UE 101 via various 3GPP RATs (including 5G, 4G, and 3G/2G). The non-3 GPP access 103 can include an Access Point (AP) that provides radio access for the UE 101 via a non-3 GPP RAT (including WiFi). The UE 101 may gain access to the data network 120 through the 3GPP access 102, AMF 110, SMF 111, and UPF 113. The UE 101 may gain access to the data network 120 through non-3 GPP access 103, N3IWF 112, AMF 110, SMF 111, and UPF 113. The UE 101 may be equipped with a single Radio Frequency (RF) module or transceiver or multiple RF modules or transceivers for services via different RATs/CNs. In some examples, the UE 101 may be a smart phone, a wearable device, an internet of things (IoT) device, a tablet computer, or the like.

If the UE registers through both the 3GPP access and the non-3 GPP access, the UE may receive messages from both accesses. For example, when the UE receives the deregistration request message from the network, the deregistration may be obtained through the 3GPP access when the UE receives the deregistration request message via the non-3 GPP access. In the current specification, the cause processing is determined by the access type of the received message. If a message is received via 3GPP access and the UE is operating in single registration mode, then in case of receiving DETACH REQUEST with the same value and with the separated type EMM cause set to "no reattach required", the UE processes the EMM parameter as specified in 3GPP TS24.301, or the UE sets EPS update status to not update EU2, resets the attach attempt counter, and enters status EMM deregistration. However, if a message is received via a non-3 GPP access, some processing for the 3GPP access will be missed. For example, if a message is received via a non-3 GPP access, the EMM parameters will not be handled correctly. Furthermore, if a message is received via a 3GPP access and the received access type indicates a non-3 GPP access, the UE will accidentally process the EMM parameters in error.

According to one novel aspect, a method of handling deregistration and EPS Mobility Management (EMM) parameters of a 3GPP when a UE receives a deregistration request message via a non-3 GPP is presented. As shown in fig. 1, UE 101 registers with a 5G network through both 3GPP access 102 and non-3 GPP access 103 (130). Later, the UE 101 receives a network-initiated de-registration request message over the non-3 GPP access 103 (131). The UE 101 then determines the access type and 5GMM cause value contained in the deregistration request (132). If the access type indicates 3GPP or indicates both 3GPP and non-3 GPP, UE 101 performs deregistration and processes EMM parameters based on the 5GMM cause value (133). The processing of EMM parameters by the UE 101 avoids possible accidental use, such as during the next 4G attachment procedure.

Note that the access type exists in the deregistration type IE in the deregistration request message. The current specification specifies that the UE handles the 5GMM reason depending on which access the message is received through, which is incorrect. In a novel aspect, the UE 101 processes EMM parameters of the deregistration procedure according to the access type in the received deregistration type IE. Upon receiving the de-registration request (DEREGISTRATION REQUEST) message, and the de-registration request is for a 3GPP access or for both a 3GPP access and a non-3 GPP access, the UE 101 should perform a local release of PDU sessions over the 3GPP access and the non-3 GPP access (if any). Based on the 5GMM reason, the UE 101 also processes corresponding EMM parameters including EMM status, EPS update status, 4G-GUTI, last accessed registration TAI, TAI list, eKSI, and attach attempt counter.

Fig. 2 illustrates a simplified block diagram of a wireless device (e.g., UE 201 and network entity 211) according to an embodiment of the present invention. The network entity 211 may be a base station and/or an AMF/SMF. The network entity 211 has an antenna 215 that sends and receives radio signals. A radio frequency RF transceiver module 214 coupled to the antenna receives RF signals from the antenna 215, converts the RF signals to baseband signals and transmits the baseband signals to the processor 213. The RF transceiver 214 also converts the baseband signal received from the processor 213 into an RF signal and transmits it to the antenna 215. The processor 213 processes the received baseband signal and invokes different functional modules to perform functions in the base station 211. Memory 212 stores program instructions and data 220 to control the operation of base station 211. In the example of fig. 2, the network entity 211 further comprises a protocol stack 280 and a set of control function modules and circuits 290. The protocol stack 280 includes a Non-Access-Stratum (NAS) layer to communicate with AMF/SMF/MME entities connected to the core network, a radio resource Control (Radio Resource Control, RRC) layer for higher layer configuration and Control, a packet data convergence protocol/radio link Control (PACKET DATA Convergence Protocol/Radio Link Control, PDCP/RLC) layer, a medium Access Control (MEDIA ACCESS Control, MAC) layer, and a Physical (PHY) layer. In one example, the control function module and circuit 290 includes: connection processing circuitry 292 that processes registration circuitry 291 for registration procedures, processes signaling connections; and configuration and control circuitry 293 that provides different parameters to configure and control relevant functions of the UE including registration and de-registration. The network entity 211 may be a 5GS network element or a plurality of 5GS network elements (e.g., access network + AMF + N3IWF + SMF, etc.).

Similarly, the UE 201 has a memory 202, a processor 203, and a Radio Frequency (RF) transceiver module 204. The RF transceiver 204 is coupled to the antenna 205, receives RF signals from the antenna 205, converts the RF signals to baseband signals, and transmits the baseband signals to the processor 203. The RF transceiver 204 also converts the baseband signal received from the processor 203 into an RF signal and transmits it to the antenna 205. The processor 203 processes the received baseband signals and invokes various functional modules and circuits to perform functions in the UE 201. The memory 202 stores data and program instructions 210 to be executed by the processor to control the operation of the UE 201. Suitable processors include, by way of example, a special purpose processor, a digital signal processor (DIGITAL SIGNAL processor, DSP), a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, a controller, microcontrollers, application SPECIFIC INTEGRATED Circuits (ASIC), file programmable gate array (file programmable GATE ARRAY, FPGA) circuits, and other types of integrated circuits (INTEGRATED CIRCUIT, ICs), and/or state machines. A processor associated with the software may be used to implement and configure the functions of the UE 201.

UE 201 also includes a protocol stack 260 and a set of control function modules and circuitry 270. The protocol stack 260 includes a NAS layer to communicate with an AMF/SMF/MME entity connected to the core network, an RRC layer for higher layer configuration and control, a PDCP/RLC layer, a MAC layer, and a PHY layer. The control function modules and circuitry 270 may be implemented and configured by software, firmware, hardware, and/or combinations thereof. When executed by the processor via program instructions contained in the memory, the control function modules and circuits cooperate to allow the UE 201 to perform implementation and functional tasks and functions in the network. In one example, the control function module and circuitry 270 includes: a registration processing circuit 271 that performs registration and de-registration procedures with the network; access and connection processing circuitry 272 that processes RRC and NAS signaling connections; and configuration and control circuitry 273 that processes configuration and control parameters (including maintaining and processing a set of EMM parameters).

Fig. 3 illustrates an example of a deregistration type IE carrying an access type, and the UE processes the deregistration procedure and EMM parameters based on the access type. For a network initiated de-registration procedure, the network sends a de-registration request message to the UE. The deregistration request message carries a deregistration type information element (information element, IE) indicating a deregistration type field, a disconnect field, a re-registration required field, and an access type field. The deregistration request message also carries a 5GMM cause value indicating the reason for deregistration. Specifically, the deregistration type IE includes an "access type" field having two bits, which indicates the access type to which the deregistration request should be applied. The "access type" field has two bits, bit value "01" represents a 3GPP access, bit value "10" represents a non-3 GPP access, and bit value "11" represents both a 3GPP access and a non-3 GPP access. When the UE receives the deregistration request message through the non-3 GPP access type, the UE still needs to check the "access type" carried by the deregistration type IE. If the access type indicates a 3GPP access type, or indicates both a 3GPP access and a non-3 GPP access type, the UE determines whether the deregistration procedure is for a 3GPP access, or for both a 3GPP access and a non-3 GPP access. Thus, the UE performs de-registration and processes corresponding EMM parameters based on the access type. When the UE receives the deregistration request message through the 3GPP access type, the UE also needs to check the "access type" carried by the deregistration type IE. If the access type indicates a non-3 GPP access, the UE determines that the de-registration procedure is for the non-3 GPP access. Thus, the UE performs the de-registration and skipping of the corresponding EMM parameters based on the access type.

Fig. 4 illustrates an example of a 5GMM cause value carried by a deregistration request message, and the UE processes the deregistration procedure and EMM parameters based on the 5GMM cause value. For a network initiated de-registration procedure, the network sends a de-registration request message to the UE. The deregistration request message carries a deregistration type Information Element (IE) and also carries a 5GMM cause value indicating the reason for deregistration. Specifically, the 5GMM cause value may include the following values: #3 (illegal UE), #6 (illegal ME), #7 (no 5GS service allowed), #11 (no PLMN allowed), #12 (no tracking area allowed), #13 (no roaming allowed in the tracking area), #15 (no cell in tracking area), #22 (congested), #27 (no N1 mode allowed), #62 (no network slice available), #78 (no PLMN operation allowed at the current UE location), #79 (no UAS service allowed), and #93 (log-in service termination). Based on the 5GMM cause value, the UE may perform de-registration and process EMM parameters accordingly.

In one example, the network determines that signaling congestion has occurred and decides to unregister the UE with a congestion cause value (# 22) and sends a unregister request message to the UE. The UE registers with both the 3GPP access and the non-3 GPP access and receives a de-registration request message through the non-3 GPP access. The deregistration request message carries the 5GMM reason and the access type in the deregistration type IE. The UE determines whether the de-registration request/procedure is for 3GPP access or for both 3GPP access and non-3 GPP access, and the UE also processes EMM parameters accordingly. If the 5GMM is due to #22 (congestion) and the UE is operating in single registration mode, the UE sets the EPS update state to not update EU2, resets the attach attempt counter, and enters the state EMM de-registration. Note that regardless of which access the deregistration request message is received over, the UE may determine which access the deregistration request/procedure is for via the access type in the deregistration type IE of the received deregistration message. When the received access type is 3GPP access, the UE determines that the de-registration request/procedure is for 3GPP access. When the received access type is 3GPP access and non-3 GPP access, the UE determines that the deregistration request/procedure is for 3GPP access and non-3 GPP access.

Fig. 5 illustrates one embodiment of a sequence flow between a UE 501 and a 5G network for a de-registration procedure in accordance with one novel aspect. The UE 501 may register to the 5G network through 3GPP access via two different alternatives. In a first alternative, the UE 501 attaches to the 4g 3gpp network first and then registers with the 5g 3gpp network later. In step 511, the UE 501 attaches to the 4G network through 3GPP access. The UE 501 obtains EPS Mobility Management (EMM) parameters from the network, such as a 4G globally unique temporary ID (global unique temporary ID, GUTI), a tracking area identity (TRACKING AREA IDENTITY, TAI) list, and a keyset identifier (KEY SET IDENTIFIER, EKSI). The UE 501 also maintains a list of other EMM parameters such as: EMM status, EPS update status, last accessed registration TAI, and attach attempt counter. In step 512, the UE 501 performs an intersystem change from 4g 3gpp to 5g 3 gpp. The UE 501 continues to maintain a list of EMM parameters in 5g 3 gpp. In a second alternative, the UE 501 registers directly with the 5G network over 3GPP access and maintains a list of EMM parameters in the 5G 3 GPP. In this case, the most important parameter to be maintained is EMM status. In the single registration mode, the states should always be synchronized, i.e. the 5GMM state is registered, and the EMM state should also be registered, so that the UE knows that the UE should perform TAU procedure when it enters S1 mode (i.e. decides which procedure to perform depending on the EMM state). In step 521, the UE 501 enters EMM state of EMM registration when the UE 501 successfully completes the registration procedure through 3GPP access in 5g N1 mode and when the UE is operating in single registration mode. In step 531, the UE 501 registers with the 5G network through a non-3 GPP access.

The UE 501 is now registered with 5G 3GPP and also with 5G non-3 GPP. In one example, in step 541, the UE 501 establishes one or more PDU sessions over 3GPP and/or non-3 GPP access. The one or more PDU sessions may be a single access PDU session or a multiple access PDU session for data communication. The PDU session defines an association between the UE and a data network providing the PDU connectivity service. Each PDU session is identified by a PDU session ID and may be established by the 3GPP RAN and/or by the non-3 GPP AN. 5GS session management (5GS session management,5GSM) for PDU sessions over both 3GPP access and non-3 GPP access is managed by AMF and SMF via NAS signaling. The UE 501 may send and receive signaling and data over the established PDU session via 3GPP access and/or non-3 GPP access.

Later, in step 551, the 5G network determines that the condition triggering the de-registration procedure of the UE 501 is satisfied. For example, network congestion occurs and the network decides to initiate a de-registration procedure for the UE 501. In step 552, the network sends a de-registration request message to the UE 501 over the non-3 GPP access. The deregistration request message carries a deregistration type IE and a 5GMM cause value. The deregistration type IE also includes an access type indicating that the deregistration procedure should be applied for 3GPP, for non-3 GPP, or for both 3GPP and non-3 GPP. If the access type indicates a 3GPP access, or indicates a 3GPP access and a non-3 GPP access, the UE 501 still determines that the requested deregistration procedure is for a 3GPP access even though the deregistration request message itself is received through a non-3 GPP access. In step 553, the UE 501 locally releases all established PDU sessions (if any). In step 554, the UE 501 completes the deregistration procedure to deregister from the 5G 3GPP, for example, by 3GPP sending a deregistration accept (DE-REGISTRATION ACCEPT) message to the 5G network.

In step 561, based on the 5GMM cause value, the UE 501 also processes the previously maintained EMM parameters accordingly. The EMM parameters include EMM status, EPS update status, 4G-GUTI, last accessed registration TAI, TAI list and eKSI, and attach attempt counter. For example, due to 3GPP congestion (e.g., 5GMM cause value # 22), the UE 501 may delete the 4G-GUTI. Further, the USIM of the UE 501 should be considered invalid for non-EPS services until the UICC closing or containing the USIM is removed or the timer T3245 expires.

Fig. 6 is a flow chart of a method of handling deregistration and EPS Mobility Management (EMM) parameters of 3GPP when a UE receives a deregistration request message via non-3 GPP according to one novel aspect of the present invention. In step 601, the UE maintains a set of EPS Mobility Management (EMM) parameters, wherein the UE is registered with the 5G network. In step 602, the UE also registers with the 5G network through a non-3 GPP access. In step 603, the UE receives a deregistration request message from the 5G network, wherein the message carries a deregistration type Information Element (IE) including an access type and a 5GMM cause value. In step 604, the UE performs a deregistration procedure to deregister from the 5g 3gpp and processes EMM parameters based on the access type and the 5GMM cause value. In one embodiment, the set of EMM parameters includes at least one of EMM status, EPS update status, 4G Globally Unique Temporary ID (GUTI), last accessed registration Tracking Area Identity (TAI), TAI list, and keyset identifier (eKSI), and an attach attempt counter.

Although the present invention has been described in connection with certain specific embodiments for purposes of illustration, the present invention is not limited thereto. Accordingly, various modifications, adaptations, and combinations of the various features of the described embodiments can be practiced without departing from the scope of the invention as set forth in the claims.

Claims (20)

1. A method, the method comprising:

a User Equipment (UE) maintains a set of EPS Mobility Management (EMM) parameters, wherein the UE is registered to a 5G network through 3GPP access;

The UE is registered to the 5G network through non-3 GPP access;

receiving a deregistration request message from the 5G network, wherein the deregistration request message carries a deregistration type information element IE including an access type and a 5GMM cause value; and

A deregistration procedure is performed to deregister from the 5g 3gpp and process the EMM parameters based on the access type and the 5GMM cause value.

2. The method of claim 1, wherein the message is received over a non-3 GPP access and the access type indicates a 3GPP access or indicates both a 3GPP access and a non-3 GPP access.

3. The method of claim 1, wherein the set of EMM parameters includes an EMM status, an EPS update status, a 4G globally unique temporary ID GUTI, at least one of a last accessed registration tracking area identity TAI, a TAI list, and a key set identifier eKSI, and an attach attempt counter.

4. A method according to claim 3, wherein the UE sets the EPS update state to not update EU2, resets the attach attempt counter, and enters an EMM de-registration state.

5. The method of claim 1, wherein the 5GMM cause value indicates one of an illegal UE, an illegal ME, disallowing 5GS service, disallowing PLMN, disallowing tracking area, disallowing roaming in the tracking area, no suitable cell in the tracking area, congestion, disallowing N1 mode, no network slice available, disallowing PLMN operation at a current UE location, disallowing UAS service and login service termination.

6. The method of claim 1, wherein the UE registers with a 4G network through 3GPP access and then performs an intersystem change to the 5G network through 3 GPP.

7. The method of claim 1, wherein the UE registers with the 5G network through 3GPP and enters EMM registration state upon successful registration.

8. The method of claim 1, wherein the 5GMM cause value indicates network congestion, and wherein the UE deletes 4G-GUTI as one of the EMM parameters.

9. The method of claim 1, wherein the UE operates in a single registration mode.

10. The method of claim 1, wherein the access type indicates a 3GPP access and the UE determines that the de-registration procedure is for a 3GPP access.

11. The method of claim 1, wherein the access type indicates a 3GPP access and a non-3 GPP access, and the UE determines that the de-registration procedure is for both 3GPP access and non-3 GPP access.

12. A user equipment, UE, the UE comprising:

A registration circuit that registers to a 5G network over a non-3 GPP access, wherein the UE maintains a set of EPS mobility management EMM parameters;

A receiver that receives a deregistration request message from the 5G network, wherein the deregistration request message carries a deregistration type information element IE including an access type and a 5GMM cause value; and

A deregistration circuit performs a deregistration procedure to deregister the UE from the 5g 3gpp and processes the EMM parameter based on the access type and the 5GMM cause value.

13. The UE of claim 12, wherein the message is received over a non-3 GPP access and the access type indicates a 3GPP access or indicates both a 3GPP access and a non-3 GPP access.

14. The UE of claim 12, wherein the set of EMM parameters includes an EMM status, an EPS update status, a 4G globally unique temporary ID GUTI, at least one of a last accessed registration tracking area identity TAI, a TAI list, and a key set identifier eKSI, and an attach attempt counter.

15. The UE of claim 14, wherein the UE sets the EPS update state to not update EU2, resets the attach attempt counter, and enters an EMM de-registration state.

16. The UE of claim 12, wherein the 5GMM cause value indicates one of an illegal UE, an illegal ME, a disallowed 5GS service, a disallowed PLMN, a disallowed tracking area, a disallowed roaming in the tracking area, no suitable cell in the tracking area, congestion, a disallowed N1 mode, no network slice available, a disallowed PLMN operating at a current UE location, a disallowed UAS service, and a logged on service termination.

17. The UE of claim 12, wherein the UE registers with a 4G network over 3GPP access and then performs an intersystem change to the 5G network over 3 GPP.

18. The UE of claim 12, wherein the UE registers with the 5G network through 3GPP and enters EMM registration state upon successful registration.

19. The UE of claim 12, wherein the 5GMM cause value indicates network congestion, and wherein the UE deletes 4G-GUTI as one of the EMM parameters.

20. The UE of claim 12, wherein the access type indicates a 3GPP access and a non-3 GPP access, and the UE determines that the de-registration procedure is for a 3GPP access and a non-3 GPP access.