Patent Publication Number: US-2023142552-A1

Title: Radio capability change

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to U.S. patent application Ser. No. 16/417,155 entitled “RADIO CAPABILITY CHANGE” and filed on May 20, 2019 for Genadi Velev, Prateek Basu Mallick, Joachim Loehr, and Ravi Kuchibhotla, which application is incorporated herein by reference. Application Ser. No. 16/417,155 claims priority to U.S. Provisional Patent Application No. 62/673,790 entitled “RADIO CAPABILITY MODIFICATION FOR DUAL REGISTRATION TERMINALS” and filed on May 18, 2018 for Genadi Velev, Prateek Basu Mallick, Joachim Loehr, and Ravi Kuchibhotla, which is incorporated herein by reference. 
    
    
     FIELD 
     The subject matter disclosed herein relates generally to wireless communications and more particularly relates to radio capability change. 
     BACKGROUND 
     In certain wireless communications networks, an evolved packet core network (“EPC”) and a fifth generation core network (“5GC”) may be deployed without an N26 interface. The N26 interface supports EPS/5GS interworking, thus a User Equipment (“UE”) may simultaneously register with an evolved packet system (“EPS”) and a fifth-generation system (“5GS”), referred to as Dual Registration (“DR”) mode for interworking between EPS/E-UTRAN and 5GS/NR. However, when a UE operating in DR mode goes out of 5GS/NR coverage and enters an Evolved UMTS Terrestrial Radio Access (“E-UTRA”) cell providing access to both EPC and 5GC, continuing DR mode would undesirably result in the UE: A) using the same cell to connect to two different CNs and B) having two Radio Resource Control (“RRC”) connections to the same Evolved Node B (“eNB”), whereas the one RRC connection is for EPC and the other one to 5GC. 
     BRIEF SUMMARY 
     Methods are disclosed for modifying a radio capability. Apparatuses and systems also perform the functions of the methods. The methods may also be embodied in one or more computer program products comprising executable code. 
     A method of a first network entity for modifying a radio capability includes receiving, from a UE, a first message indicating an updated radio access capability and deleting a radio access capability associated with the UE based at least in part on the received first message. The method includes transmitting, to a second network entity, a second message excluding the radio access capability associated with the UE and receiving, from the second network entity, a third message indicating a new radio access capability associated with the UE. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A more particular description of the embodiments briefly described above will be rendered by reference to specific embodiments that are illustrated in the appended drawings. Understanding that these drawings depict only some embodiments and are not therefore to be considered to be limiting of scope, the embodiments will be described and explained with additional specificity and detail through the use of the accompanying drawings, in which: 
         FIG.  1    is a schematic block diagram illustrating one embodiment of a wireless communication system for modifying a radio capability; 
         FIG.  2    is a block diagram illustrating one embodiment of a network architecture for modifying a radio capability; 
         FIG.  3 A  is a block diagram illustrating one procedure for modifying a radio capability; 
         FIG.  3 B  is a continuation of  FIG.  3 A ; 
         FIG.  4    is a block diagram illustrating another procedure for modifying a radio capability; 
         FIG.  5    is a block diagram illustrating a user equipment apparatus for modifying a radio capability; 
         FIG.  6    is a flow chart diagram illustrating a first method of modifying a radio capability; 
         FIG.  7    is a flow chart diagram illustrating a second method of modifying a radio capability; and 
         FIG.  8    is a flow chart diagram illustrating a third method of modifying a radio capability. 
     
    
    
     DETAILED DESCRIPTION 
     As will be appreciated by one skilled in the art, aspects of the embodiments may be embodied as a system, apparatus, method, or program product. Accordingly, embodiments may take the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, micro-code, etc.) or an embodiment combining software and hardware aspects that may all generally be referred to herein as a “circuit,” “module” or “system.” Furthermore, embodiments may take the form of a program product embodied in one or more computer readable storage devices storing machine readable code, computer readable code, and/or program code, referred hereafter as code. The storage devices may be tangible, non-transitory, and/or non-transmission. The storage devices may not embody signals. In a certain embodiment, the storage devices only employ signals for accessing code. 
     Any combination of one or more computer readable medium may be utilized. The computer readable medium may be a computer readable storage medium. The computer readable storage medium may be a storage device storing the code. The storage device may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, holographic, micromechanical, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. 
     More specific examples (a non-exhaustive list) of the storage device would include the following: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random-access memory (“RAM”), a read-only memory (“ROM”), an erasable programmable read-only memory (“EPROM” or Flash memory), a portable compact disc read-only memory (“CD-ROM”), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In the context of this document, a computer readable storage medium may be any tangible medium that can contain or store a program for use by or in connection with an instruction execution system, apparatus, or device. 
     Code for carrying out operations for embodiments may be any number of lines and may be written in any combination of one or more programming languages including an object-oriented programming language such as Python, Ruby, Java, Smalltalk, C++, or the like, and conventional procedural programming languages, such as the “C” programming language, or the like, and/or machine languages such as assembly languages. The code may execute entirely on the user&#39;s computer, partly on the user&#39;s computer, as a stand-alone software package, partly on the user&#39;s computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer may be connected to the user&#39;s computer through any type of network, including a local area network (“LAN”) or a wide area network (“WAN”), or the connection may be made to an external computer (for example, through the Internet using an Internet Service Provider). 
     Reference throughout this specification to “one embodiment,” “an embodiment,” or similar language means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, appearances of the phrases “in one embodiment,” “in an embodiment,” and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment, but mean “one or more but not all embodiments” unless expressly specified otherwise. The terms “including,” “comprising,” “having,” and variations thereof mean “including but not limited to,” unless expressly specified otherwise. An enumerated listing of items does not imply that any or all of the items are mutually exclusive, unless expressly specified otherwise. The terms “a,” “an,” and “the” also refer to “one or more” unless expressly specified otherwise. 
     Furthermore, the described features, structures, or characteristics of the embodiments may be combined in any suitable manner. In the following description, numerous specific details are provided, such as examples of programming, software modules, user selections, network transactions, database queries, database structures, hardware modules, hardware circuits, hardware chips, etc., to provide a thorough understanding of embodiments. One skilled in the relevant art will recognize, however, that embodiments may be practiced without one or more of the specific details, or with other methods, components, materials, and so forth. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of an embodiment. 
     Aspects of the embodiments are described below with reference to schematic flowchart diagrams and/or schematic block diagrams of methods, apparatuses, systems, and program products according to embodiments. It will be understood that each block of the schematic flowchart diagrams and/or schematic block diagrams, and combinations of blocks in the schematic flowchart diagrams and/or schematic block diagrams, can be implemented by code. The code may be provided to a processor of a general-purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions/acts specified in the schematic flowchart diagrams and/or schematic block diagrams block or blocks. 
     The code may also be stored in a storage device that can direct a computer, other programmable data processing apparatus, or other devices to function in a particular manner, such that the instructions stored in the storage device produce an article of manufacture including instructions which implement the function/act specified in the schematic flowchart diagrams and/or schematic block diagrams block or blocks. 
     The code may also be loaded onto a computer, other programmable data processing apparatus, or other devices to cause a series of operational steps to be performed on the computer, other programmable apparatus, or other devices to produce a computer implemented process such that the code which execute on the computer or other programmable apparatus provide processes for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks. 
     The schematic flowchart diagrams and/or schematic block diagrams in the Figures illustrate the architecture, functionality, and operation of possible implementations of apparatuses, systems, methods, and program products according to various embodiments. In this regard, each block in the schematic flowchart diagrams and/or schematic block diagrams may represent a module, segment, or portion of code, which includes one or more executable instructions of the code for implementing the specified logical function(s). 
     It should also be noted that, in some alternative implementations, the functions noted in the block may occur out of the order noted in the Figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. Other steps and methods may be conceived that are equivalent in function, logic, or effect to one or more blocks, or portions thereof, of the illustrated Figures. 
     Although various arrow types and line types may be employed in the flowchart and/or block diagrams, they are understood not to limit the scope of the corresponding embodiments. Indeed, some arrows or other connectors may be used to indicate only the logical flow of the depicted embodiment. For instance, an arrow may indicate a waiting or monitoring period of unspecified duration between enumerated steps of the depicted embodiment. It will also be noted that each block of the block diagrams and/or flowchart diagrams, and combinations of blocks in the block diagrams and/or flowchart diagrams, can be implemented by special purpose hardware-based systems that perform the specified functions or acts, or combinations of special purpose hardware and code. 
     The description of elements in each figure may refer to elements of proceeding figures. Like numbers refer to like elements in all figures, including alternate embodiments of like elements. 
     Generally, the present disclosure describes systems, methods, and apparatus for modifying a radio capability. In various embodiments, a UE may operate in a Dual Registration (“DR”) mode having simultaneous registrations with EPS and 5GS. In some embodiments, the DR mode is used only in networks which do not support interworking via N26 interface. 
     In a given public land mobile network (“PLMN”), the Access and mobility Management Function (“AMF”) (in the 5GC) and the Mobility Management Entity (“MIME”), (in the EPC) provide an indication to UEs that EPS-5GS interworking without N26 is supported. This indication may be provided during Initial Registration (in 5GC) or during the Attach procedure (in EPC). Moreover, this indication is valid for the entire Registered PLMN and for PLMNs equivalent to the Registered PLMN. Additionally, the same indication is provided to all UEs served by the same PLMN. 
     Accordingly, UEs that operate in a PLMN that supports EPS-5GS interworking without N26 (e.g., operable in DR mode) may use this indication to decide whether to register early in the target system. Note that the network does not provide mapped Quality of Service (“QoS”) parameters to a UE in DR mode, i.e., if interworking with N26 is not supported. 
     In various embodiments, the UE provides the following indications to the core network (e.g., AMF or MME) during Initial Attach to EPC or during Registration to 5GC: 
     In some embodiments, the UE indicates its support of EPC Non-Access Stratum (“NAS”) during the registration procedure with the AMF or its support of 5GC NAS during the attach procedure with the MME. For example, the UE may provide the indication using the “UE Network Capability” parameter. This indication might be used by the AMF/MME to select combo PGW-C+SMF node for EPS-5GS interworking. 
     Additionally, the UE may indicate that it supports Request Type flag “handover” for Packet Data Network (“PDN”) connectivity request during the attach procedure in EPC and during initial registration and mobility Registration Update in 5GC. Note that this indication may be used for Internet Protocol (“IP”) address preservation in the case of interworking without N26. 
     For interworking without N26, the UE needs to indicate that it is moving from 5GC (or from EPC) so that the MME or AMF does not include “initial attach” indicator to the Home Subscriber Server (“HSS”) and Unified Data Management entity (“UDM”). Because the “initial attach” indicator is not included, the HSS+UDM does not cancel the earlier registration of AMF or MME. 
       FIG.  1    depicts a wireless communication system  100  for suspending services in a first core network while attached to a second core network, according to embodiments of the disclosure. In one embodiment, the wireless communication system  100  includes at least one remote unit  105 , a first access network  120  containing at least one base unit  110 , a second access network  125  containing at least one base unit  110 , wireless communication links  115  between remote unit  105  and base unit  110 , a first core network  130 , and a second core network  140 . Even though a specific number of remote units  105 , access networks  120 ,  125 , base units  110 , wireless communication links  115 , and core networks  130 ,  140  are depicted in  FIG.  1   , one of skill in the art will recognize that any number of remote units  105 , access networks  120 ,  125 , base units  110 , wireless communication links  115 , and core networks  130 ,  140  may be included in the wireless communication system  100 . In various embodiments, the access networks  120 ,  125  may contain one or more wireless LAN (“WLAN”) (e.g., Wi-Fi™) access points (“APs”). Here, the first access network  120 , second access network  125 , first core network  130  and second core network  140  belong to the same mobile communication network (e.g., the same PLMN). 
     In one implementation, the wireless communication system  100  is compliant with the 5G system and the Long Term Evolution (“LTE”) system specified in the Third Generation Partnership Project (“3GPP”) specifications. More generally, however, the wireless communication system  100  may implement some other open or proprietary communication network, for example, Worldwide Interoperability for Microwave Access (“WiMAX”), among other networks. The present disclosure is not intended to be limited to the implementation of any particular wireless communication system architectures or protocols. 
     In one embodiment, the remote units  105  may include computing devices, such as desktop computers, laptop computers, personal digital assistants (“PDAs”), tablet computers, smart phones, smart televisions (e.g., televisions connected to the Internet), smart appliances (e.g., appliances connected to the Internet), set-top boxes, game consoles, security systems (including security cameras), vehicle on-board computers, network devices (e.g., routers, switches, modems), or the like. In some embodiments, the remote units  105  include wearable devices, such as smart watches, fitness bands, optical head-mounted displays, or the like. Moreover, the remote units  105  may be referred to as subscriber units, mobiles, mobile stations, users, terminals, mobile terminals, fixed terminals, subscriber stations, UEs, user terminals, a device, or by other terminology used in the art. The remote units  105  may communicate directly with one or more of the base units  110  via uplink (“UL”) and downlink (“DL”) communication signals. Furthermore, the UL and DL communication signals may be carried over the wireless communication links  115 . 
     In some embodiments, the remote units  105  communicate with a remote host  180  (for example, an application server) via a data path that passes through one of the core networks  130 ,  140  and through the data network  175 . For example, a remote unit  105  may establish a Protocol Data Unit (“PDU”) session (or similar data connection) to the data network  175  via the first core network  130 . The first core network  130  then relays traffic between the remote unit  105  and the remote host  180  using the PDU session. As another example, a remote unit  105  may establish a PDN connection to the data network  175  via the second core network  140 . The second core network  140  then relays traffic between the remote unit  105  and the remote host  180  using the PDN connection. 
     The base units  110  may be distributed over a geographic region. In certain embodiments, a base unit  110  may also be referred to as an access terminal, an access point, a base, a base station, a Node-B, an eNB, a Next Generation Node B (“gNB”), a Home Node-B, a relay node, a device, or by any other terminology used in the art. The base units  110  are generally part of a radio access network (“RAN”), such as the first access network  120  (e.g., NG-RAN) and/or the second access network  125  (e.g., Evolved UMTS Terrestrial Radio Access Network (“E-UTRAN”)), that may include one or more controllers communicably coupled to one or more corresponding base units  110 . These and other elements of the radio access network are not illustrated, but are well known generally by those having ordinary skill in the art. 
     The base units  110  may serve a number of remote units  105  within a serving area, for example, a cell or a cell sector via a wireless communication link  115 . The base units  110  may communicate directly with one or more of the remote units  105  via communication signals. Generally, the base units  110  transmit downlink (“DL”) communication signals to serve the remote units  105  in the time, frequency, and/or spatial domain. Furthermore, the DL communication signals may be carried over the wireless communication links  115 . The wireless communication links  115  may be any suitable carrier in licensed or unlicensed radio spectrum. The wireless communication links  115  facilitate communication between one or more of the remote units  105  and/or one or more of the base units  110 . 
     As depicted, the wireless communication system  100  includes both a first core network  130  and a second core network  140  and various interworking network functions for to support interworking between the user plane and certain control plane functions in the first core network  130  and the second core network  140 . The first core network  130  includes an AMF  135  that is not shared with the second core network  140 . Similarly, the second core network  140  includes an MME  145  and a Serving Gateway (“SGW”)  150  that are note shared with the first core network  130 . However, there is a combined User Plane Function (“UPF”) and Packet Data Gateway (“PGW”)-user-plane (i.e., “UPF+PGW-U”)  155 , a combined Session Management Function (“SMF”) and PGW-control-plane (i.e., “SMF+PGW-C”)  160 , a combined Policy Control Function (“PCF”) and Policy and Charging Rules Function (“PCRF”) (i.e., “PCF+PCRF”)  165 , and a combined HSS and UDM (i.e., “HSS+UDM”) that support interworking between the first core network  130  and second core network  140 . Note that the notions “SMF+PGW-C” and “UPF+PGW-U” are used to show that the network functions used for, e.g., PDU Sessions in 5GC and PDN Connections in EPC are common, in case that IP session continuity is required during transfer of PDU Sessions to PDN Connections and vice-versa. Although specific numbers and types of network functions are depicted in  FIG.  1   , one of skill in the art will recognize that any number and type of network functions may be included in the mobile core networks  130  and/or  140 . 
     As depicted, the wireless communication system  100  includes various network interfaces that facilitate communication among the core network (“CN”) elements. For example, a base unit  110  (or RAN) may communicate with the AMF  135  via the N2 interface and with the UPF+PGW-U  155  via the N3 interface. As another example, a base unit  110  may communicate with the MIME  145  via the S1-MME interface and with the SGW via the S1-U interface. Other network interfaces are depicted, including, but not limited to, a N4 interface between the UPF+PGW-U  155  and the SMF+PGW-C  160 , a N7 interface between the SMF+PGW-C  160  and the PCF+PCRF  165 , a N8 interface between the AMF  135  and the HSS+UDM  170 , a N10 interface between the SMF+PGW-C  160  and the HSS+UDM  170 , a N11 interface between the AMF  135  and the SMF+PGW-C  160 , a N15 interface between the AMF  135  and the PCF+PCRF  165 , a S5-U interface between the SGW  150  and the UPF+PGW-U  155 , a S5-C interface between the SGW  150  and the SMF+PGW-C  160 , a S6a interface between the MME  145  and the HSS+UDM  170 , and the S11 interface between the MME  145  and the SGW  150 . 
     Although not depicted, the wireless communication system  100  may support a N1 interface between the remote unit  105  and the AMF  135 . Note, however, that there is no network interface between the AMF  135  and the MME  145  (i.e., no N26 interface). This is because the AMF  135  and the MME  145  are not communicatively coupled. Accordingly, inter-system handover from the 5GC to EPC (or vice versa) is not supported. 
     In various embodiments, the remote unit  105  may register with a first communication system and indicate (e.g., announce) one or more radio capabilities to the first communication system. Here, the radio capabilities relate to RAT. The remote unit  105  later determines to register with a second communication system and updates the one or more UE radio capabilities using a NAS procedure. Here, the first and second communication systems may belong to the same PLMN. In one embodiment, the first communication system includes an EPC and wherein the second communication system comprises a 5GC. 
     In certain embodiments, the remote unit  105  may perform a radio capability exchange towards a base unit  110  (e.g., a RAN node). Here, the remote unit  105  updates one or more RAT capabilities of the second communication system during the radio capability exchange. 
     If the remote unit  105 &#39;s NG-RAN UE Radio Capability information changes while in CM-IDLE state, the remote unit  105  performs the Registration procedure with the Registration type set to Mobility Registration Update indicating “UE Radio Capability Update”. When the AMF receives Registration Update Request with “UE Radio Capability Update”, it shall delete any UE Radio Capability information that it has stored for the remote unit  105 . 
     If the trigger to change the remote unit  105 &#39;s NG-RAN UE Radio Capability information happens when the UE is in CM-CONNECTED state, the remote unit  105  first enters CM-IDLE state and then perform the Registration procedure with the Registration type set to Mobility Registration Update indicating “UE Radio Capability Update”. 
     To update the one or more UE radio capabilities, the remote unit  105  transitions to a UE idle state, such as the CM-IDLE state. Note that the transition of the “UE state” is in both the remote unit  105  and in the network. As described in further detail herein, the transition may be based on explicit signaling. Alternatively, this may be an implicit transition without signaling. and (within the remote unit  105 ) a NAS entity (e.g., in the NAS layer) instructs an Access Stratum (“AS”) entity (e.g., in the AS layer) to modify an AS layer capability. In one embodiment, modifying the AS layer capability comprises disabling a radio capability for a particular radio access technology. In another embodiment, modifying the AS layer capability comprises enabling a radio capability for a particular radio access technology. In certain embodiments, when entering the CM Idle state, the remote unit  105  may deactivate a radio resource control (“RRC”) idle state, e.g., using NAS signaling and/or RRC signaling. This is an instruction from the NAS layer to the AS layer to transition to RRC idle state. As such, the NAS entity in the remote unit  105  may instruct the AS entity to discard (or deactivate) the existing AS context and to modify an AS layer capability for the remote unit  105 . 
     In some embodiments, the remote unit  105  updates the one or more UE radio capabilities by having a NAS layer entity initiate a NAS update procedure. One suitable NAS update is the EPS NAS tracking area update procedure. Alternatively, the remote unit  105  may initiate the NAS update procedure by sending a 5GS NAS registration request for mobility update. 
     In other embodiments, a remote unit  105  may register with a first communication system via a radio access network (“RAN”) node, announce radio capabilities for at least one RAT to the first communication system, and detect a need to change an AS capability of the UE. In response, the remote unit  105  may send a request to the network that a particular AS capability be deprecated or disclaimed. Here, the request may be via NAS signaling or RRC signaling. Upon receiving the indication of a deprecated/disclaimed capability (e.g., AS capability), the RAN node (e.g., base unit  110 ) does not consider the deprecated AS capability (e.g., considers the remote unit  105  to not have the particular AS capability). 
     In certain embodiments, requesting that a particular AS capability be deprecated (disclaimed) includes the remote unit  105  indicating that a previously indicated (claimed) RAT capability is deprecated (disclaimed). In certain embodiments, the request that a particular AS capability be deprecated includes an indication that the network does not need to update the UE radio capability. In response to the depreciation indication (disclaiming a RAT capability), the base unit  110  (e.g., RAN node) no longer considers the deprecated capability (e.g., considers the remote unit  105  to not have the previously indicated RAT capability). 
     In one embodiment, detecting the need to change the AS capability of the UE comprises determining to register with a second communication system. In other embodiments, other trigger events may require the change in AS capability. Additionally, the remote unit  105  may later send a request to the network to abolish the deprecated AS capability. 
       FIG.  2    depicts a network architecture  200  used for suspending services in a first core network while attached to a second core network, according to embodiments of the disclosure. The network architecture  200  may be a simplified embodiment of the wireless communication system  100 . As depicted, the network architecture  200  includes a UE  205  that communicates with a 5GC  210  and with an EPC  215  via a RAN  220 . The UE  205  may be one embodiment of the remote unit  105 , the 5GC  210  may be an embodiment of the first core network  130 , and the EPC  215  may be an embodiment of the second core network  140 . Additionally, the network architecture  200  includes multiple core interworking functions  240 , such as a SMF/PGW-C interworking function, a UPF/PGW-U interworking functions, etc. Although shared by the 5GC  210  and the EPC  215 , the HSS+UDM is depicted as separate from the core interworking functions  240 . 
     In the depicted embodiment, the 5GC  210  and EPC  215  belong to the same PLMN. In various embodiments, the RAN  220  broadcasts an indication in the system information (e.g., System Information Block (“SIB”)) that the PLMN supports DR-mode. Here, the UE  205  is configured to operate in DR-mode. 
       FIG.  2    shows an example of how a UE  205  may operate in DR mode, i.e., registered to EPS and 5GC simultaneously. The UE  205  may establish PDN Connections in EPS and PDU sessions in 5GS. However, some PDN connection in EPS may not support interworking with 5GS, for example EPS-exclusive connections  265  having the S/PGW  250  as the anchor point in the user plane. Accordingly, such a PDN connection cannot be transferred to 5GS. Similarly, some PDU Sessions in 5GS may not support interworking with EPS, for example 5GS-exclusive connections  270  having the UPF  245  as the anchor point in the user plane. Accordingly, such a PDU session cannot be transferred to EPS. Yet another type of PDN connections or PDU session can support interworking between EPS and 5GS, depicted as interworking connections  275 , because the anchor point in the control plane (e.g., SMF+PGW-C) for the PDN connection or PDU session is a common entity (e.g., one of the core interworking functions  240 ) and the anchor point in the user plane (e.g., UPF+PGW-U) is also a common entity. 
     A UE  205  is expected to be able to enable (and disable) capabilities to access 5GS (e.g., 5GC  210 ). However, at the time of invention there is no access stratum procedure available to accomplish a change of UE capabilities. Thus, the UE  205  may rely on upper layer (e.g., NAS) procedures to accomplish such a change. One example of a NAS procedure is the Detach/Re-attach procedure. Note that the UE  205  NAS capability is used in the mobility management entity (e.g., MME  235  or AMF  230 ) to select a combined PGW-C+SMF entity (e.g., core interworking function  240 ) in case of the UE  205  supporting both 5GC NAS and EPC NAS. The UE  205  NAS capability is distinct from the UE  205  radio capability; thus, it should be differentiated between UE  205  NAS capability announcement and the UE  205  radio capability announcement. 
     DR mode is intended for interworking between EPS/E-UTRAN and 5GS/NR. A problem occurs when a UE  205  operating in DR mode goes out of 5GS/NR coverage and enters an E-UTRA cell providing access to both EPC  215  and 5GC  210 . The UE  205  would end-up in 1) using the same cell to connect to two different CNs (e.g., EPC  215  and 5GC  210 ) and 2) having two RRC connections to the same eNB, whereas the one RRC connection is for EPC  215  and the other one to 5GC  210 . 
     In order to avoid such scenario, the UE  205  operating in DR mode is not to send its E-UTRA capability to NG-RAN when connected to 5GS/NR to avoid being handed over to 5GC-connected E-UTRA (e.g., RAN  220 ). This prevents the UE  205  from being connected to E-UTRAN/EPC  215  and E-UTRA/5GC  210  simultaneously using separate RRC connections via a single RAN node (in the RAN  220 ) as a result of handover. However, 3GPP Release 15 (“Rel-15”) leaves unclear which capability the UE  205  is to announce when attaching to the EPS/E-UTRAN. Additionally, it is unclear whether the UE  205  is to send to the CN its NAS capabilities (5GC NAS and/or EPC NAS capabilities) when disabling/enabling in the AS layer a particular RAT radio capability. Accordingly, current standards do not specify whether the UE  205  sends its New Radio (“NR”) capability to the EPS/E-UTRAN when operating in DR mode. 
     In various embodiments, the UE  205  operating in DR mode is not to send its E-UTRA capability to NG-RAN when connected to 5GS/NR in order to avoid being handed over to 5GC-connected E-UTRA. However, Rel-15 does not provide details about the UE  205  behavior while attached/registered to the EPS. In order to avoid the configuration on Dual Connectivity (“DC”) with NR when the UE  205  is connected to E-UTRA/EPS and the simultaneous use of RRC connection in NR/5GC, in one embodiment, the UE  205  does not send its NR capability to E-UTRA when connected to EPS/E-UTRA to avoid being configured in EN-DC mode while also using NR for accessing 5GS/NR. 
     If the UE  205  has been operating in DR mode and the UE  205  deregisters from one system, e.g., the UE  205  deregisters from the 5GS (this deregistration may be implicit deregistration due to lack of coverage) and the UE  205  changes to Scheduling Request (“SR”) mode with EPS only, then the UE  205  may update its radio capability (e.g., to increase radio capability by including the NR capability) to the other system where the UE  205  continues to be registered (e.g., in the EPS). 
     Note that by increasing the radio capability, the already selected core network for existing PDU Sessions or PDN Connections may need to be reselected. For example, if the UE  205  is registered to EPS/E-UTRAN and 5GS/NR and the UE  205  a) has not indicated NR capability to E-UTRAN and b) has not indicated E-UTRA capability to NR, the corresponding core network node (e.g., MME  235 ) may have selected user plane nodes (e.g., SGW or UPF) which do not support Dual Connectivity. Accordingly, after increasing the capability, e.g., after the UE  205  indicates Dual Connectivity support with multiple RATs, the core network (e.g., MME  235 ) may need to reselect another user plane node. 
     When considering UE capabilities, it should be differentiated between NAS layer capabilities and AS layer capabilities. For example, on the NAS layer the UE  205  may be capable of DR mode, may be 5GC NAS capable and/or EPC NAS capable, the UE  205  may support user plane (“UP”) and/or control plane (“CP”) Consumer Internet-of-Things (“CIoT”) optimizations or Narrowband Internet-of-Things (“NB-IoT”) capability, to mention just some of the NAS layer capabilities. Additionally, on the AS layer, the UE  205  may support different RATs (e.g., UTRAN capable, E-UTRAN capable and/or NR capable) or different frequency bands and other features. 
     The UE  205  needs to differentiate between the following use cases for disabling/enabling 4G or 5G capability: 
     Use Case A: If the UE  205  disables 5G capability in order to stay attached with EPS only due to e.g., use of feature(s) non-supported in 5GS (e.g., ProSe, Multimedia Broadcast Multicast Services (“MBMS”), CIoT optimizations, Vehicle-to-Everything (“V2X”), etc.) but also other use cases can be possible, then the UE  205  does not indicate 5GC NAS to the EPC (e.g., MME  235 ) during NAS (e.g., TAU/Attach) procedure and the UE  205  disables the NR capability in the AS layer. With other words, “disabling 5G capability” means disabling the 5GC NAS capability and the AS capability (e.g., NR capability). 
     Similarly, if the UE  205  enables the 5G capability, then the UE  205  indicate 5GC NAS support to the EPC (e.g., MME  235 ) during NAS (e.g., TAU/Attach) procedure and the UE  205  enables the NR capability in the AS layer. 
     Please note that before disabling the 5G capability internally in the UE  205 , in order to assure clean state(s) in the network functions in 5GS and avoid unnecessary paging or other signaling, the UE  205  may deregister in the 5GS. For example, the UE  205  sends a Deregistration Request message indicating an appropriate cause, e.g., moving to other system. If explicit deregistration is performed and after the UE  205  receives the Deregistration Accept message, the UE  205  transfers to RM-Deregistered state in 5GS and the NAS layer may trigger the AS layer to disable the NR capability and the NAS layer itself disables the 5GC NAS support. The deregistration may be also implicit. 
     Use Case B: If the UE  205  disables 5G capability due to e.g., use of DR mode (but also other use cases can be possible), then the UE  205  indicates 5GC NAS support to the EPC (e.g., MME  235 ) but disables only the NR capability in the AS layer. Therefore, in case of change between DR mode and SR mode, the talk is about AS capability change (e.g., RAT capability) and not of 5G capability change. 
     Similarly, if the UE  205  enables the 5G capability due to use of DR mode, the UE  205  indicates 5GC NAS support to the EPC (e.g., MME  235 ) during NAS (e.g., TAU/Attach) procedure and the UE  205  enables the NR capability in the AS layer. 
     When the DR-capable UE  205  is initially registered with the 5GC  210  and then discovers LTE coverage, the following steps may be taken. Note that in general the UE  205  first registers with a single system e.g., the UE  205  performs initial registration to 5GC in a PLMN (see messaging  255 ). Thus, the UE  205  would initially operate in a single registration mode and can announce its radio capability for multiple RATs (e.g., capable of NR and LTE). At some point of time the UE  205  determines to perform DR mode. 
     When the DR-capable UE  205  is initially registered with the EPC  215  and then discovers NR coverage, the following steps may be taken. Note that in general the UE  205  first registers with a single system e.g., the UE  205  performs initial attach to EPC  215  in a PLMN (see messaging  260 ). Thus, the UE  205  would initially operate in a single registration mode and can announce its radio capability for multiple RATs (e.g., capable of NR and LTE). At some point of time the UE  205  determines to perform DR mode. 
     In various embodiments, when registering with the EPC  215 , the UE  205  indicates its capabilities, e.g., 5G NAS capable, support of “handover” for PDN connectivity, etc. Because the UE  205  intends to only use EPS currently (e.g., no NR coverage), the UE  205  indicate its E-UTRAN and NR capabilities to the LTE. The EPS/E-UTRAN may decide to configure Dual Connectivity with NR, if NR cell is available. The MME  235  indicates to the UE  205  that interworking with 5GS is supporting without N26. 
     While attached to the EPC  215 , the UE  205  may discover NR coverage and decide to perform DR mode, i.e., to register with 5GS. Per Rel-15, a UE  205  wanting to use one or more EPS functionalities not supported by 5G System (e.g., ProSe, MBMS, CIOT optimizations, V2X, etc.), may disable all the related radio capabilities that allow the UE  205  to access 5G System when in CM-IDLE. Thus, radio capability change may be performed in CM/EMM Idle state, e.g., in order to prevent abrupt termination of services (disruption if active bearers) in CM/EMM Connected state. 
     Accordingly, the UE  205  may transition to CM/EMM Idle state to modify its radio capabilities in the EPS. In various embodiments, the UE  205  detects internally based on implementation, configuration (e.g., initiation of DR mode, termination of DR mode, 5GS non-supported feature use, etc.) that radio capability change should be performed in a first registered system. The UE  205  first enters CM/EMM Idle state before the NAS layer requests the AS layer to reconfigure the radio capabilities (e.g., increase or decrease radio capabilities). Afterwards the UE  205  performs NAS layer signaling to 1) to request update for the UE capability update (e.g., in 5GS or EPS) and 2) to change the registration in the corresponding system. If the UE  205  is in CM/EMM Connected and RRC Inactive state for long time, the UE  205  may request the deactivation of the RRC Inactive state (or requesting Idle state due to capability change/modification) using the NAS protocol or the RRC protocol. 
     For initiating 5GS to EPS dual registration operation: if the UE  205  is aware that the network supports 5GS-EPS interworking without N26 and the UE  205  is dual registration capable and is already registered with the 5GS, when the UE  205  determines to attach to a second system (e.g., EPS) in dual registration mode, the UE  205  performs the following procedures: 
     a. If the UE  205  is in connection management (CM) CONNECTED state in the first system, the UE  205  may indicate to the CN of the first system that capability change (e.g., reduce radio capabilities by excluding the radio capabilities of the RAT of a second system) is required. This indication may be performed via NAS layer signaling. 
     b. The 5GS (e.g., AMF  230 ) may disable RRC Inactive state in the NG-RAN. 
     c. The UE  205  enters CM IDLE state. 
     d. The NAS layer of the UE  205  indicates to the AS layer to disable the LTE capability when using NR. 
     e. The NAS layer of the UE  205  initiates registration update procedure towards AMF  230  to update its capabilities. The UE  205  indicates reduced capability to the NG-RAN (e.g., NR) node. 
     f. The UE  205  initiates NAS attach procedure with a second system (EPS) for DR mode. 
     For initiating EPS to 5GS dual registration operation: if the UE  205  is aware that the network supports EPS-5GS interworking without N26 and the UE  205  is dual registration capable and is already registered with the EPS, when the UE  205  determines to attach to a second system (e.g., 5GS) in dual registration mode, the UE  205  performs the following procedures: 
     a. If the UE  205  is in connection management (CM) CONNECTED state in the first system, the UE  205  may indicate to the CN of the first system that capability change (e.g., reduce radio capabilities by excluding the radio capabilities of the RAT of a second system) is required. This indication may be performed via NAS layer signaling. 
     b. The EPS (e.g., MME  235 ) may disable RRC Inactive state in the LTE-RAN. 
     c. The UE  205  enters CM IDLE state. 
     d. The NAS layer of the UE  205  indicates to the AS layer to disable the NR capability when using LTE. 
     e. The NAS layer of the UE  205  initiates registration update procedure towards MME  235  to update its capabilities. The UE  205  indicates reduced capability to the LTE-RAN node. 
     f. The UE  205  initiates NAS register procedure with a second system (5GS) for DR mode. 
       FIGS.  3 A- 3 B  depict a first procedure  300  for radio capability change of a UE  205 , according to embodiments of the disclosure. The first procedure  300  involves the UE  205 , an NR RAN  305 , an LTE RAN  310 , the AMF  230 , the MME  235 , a SMF+PGW-C  160 , and the HSS+UDM  225 . The steps shown in  FIGS.  3 A- 3 B  are as described follows: 
     The procedure  300  begins at  FIG.  3 A . In step 0: The UE  205  is registered in 5GS (see messaging  315 ). The UE  205  has indicated support of 1) NR+LTE radio capability to the NG-RAN node and 2) EPS NAS capability to the AMF  230 . In certain embodiments, the 5GS may configure Dual Connectivity. The 5GS indicates to the UE  205  the interworking without N26 is supported. 
     Step 1: The UE  205  detects LTE coverage and determines to initiate dual registration mode of operation. The UE  205  decides to change radio capabilities in the currently used system, e.g., in the 5GS/NR (see block  320 ). The UE  205  also determines that it is in CM Connected state and either in RRC Connected or RRC Inactive state (see block  325 ). 
     Step 2: If the UE  205  is in CM/EMM Connected state, the UE  205  may determine to initiate transition to CM Idle state. For this purpose, the UE  205  may perform one of the following actions: 
     The UE  205  NAS layer may query the RRC layer about the RRC state (i.e., RRC Connected or RRC Inactive state). If the RRC state is RRC Inactive, the UE  205  may send a NAS indication to the AMF  230  to request disablement of the RRC Inactive state. For example, the UE  205  can send a Registration Request message having a type of Mobility Registration Update with indication ‘transfer to Idle state’ or ‘disable RRC Inactive state’ or a similar indication). In addition, the UE  205  may indicate the reason for transition to Idle state, e.g., UE  205  needs to change AS layer capabilities. 
     The UE  205  may send NAS Deregistration Request message to the AMF  230  with an indication that the Deregistration is due to UE  205  radio capability change and an indication that re-registration is (e.g., soon) expected (see messaging  330 ). In such case, the AMF  230  may initiate a deregistration procedure, for example the deregistration procedure described in 3GPP TS 23.502 version 15.1.0. At the end of the deregistration procedure, the UE  205  state in the AMF  230  is RM-Deregistered. The AMF  230  may however keep the security context downloaded previously from the UDM/UDR because the AMF  230  may expect re-registration soon. 
     The UE  205  may send an RRC message to the NG-RAN node (e.g., gNB) to indicate to disable the RRC Inactive state (see messaging  330 ). For this purpose, the UE  205  may perform the RRC resume procedure with an indication to disable RRC Inactive state. 
     Step 3: AMF  230  to NR RAN  305 : The AMF  230  initiates N2 procedure for disabling the RRC Inactive state, if the RRC state is RRC Inactive (see messaging  335 ). An existing N2 message or a new N2 message can be used to request the NG-RAN node to disable the RRC Inactive state. If the AMF  230  is not aware about the RRC state, the AMF  230  may request the NG-RAN node to release the UE context of the UE  205 . 
     Optionally, the AMF  230  may include an indication that the release is not urgent and can be performed upon UE Inactivity. For example, the AMF  230  may use N2 UE Context Release Request (release cause value, delay tolerant release), where the cause value may indicate the reason for releasing the UE context, e.g., UE radio capability change. The ‘delay tolerant release’ indicates to the NG-RAN node that the RRC connection can be release upon UE Inactivity (e.g., short inactivity of 5 seconds or 10 seconds), so that the release is not urgent. 
     Step 4: The NG-RAN node performs procedure for RRC Idle state transition, e.g., after Inactivity timer expires (see messaging  340 ). 
     Step 5: UE  205  in CM/EMM Idle or RM Deregistered state: the NAS layer performs AS layer modification (see block  345 ). For example, the AS layer may increase or decrease radio capabilities, e.g., by including or excluding a RAT capability. 
     The procedure  300  continues at  FIG.  3 B . In step 6a, UE  205  to CN (e.g., AMF  230 ): (Note, the UE  205  may be in CM/EMM Idle state) UE  205  initiates NAS procedure (e.g., Registration procedure) to indicate change of its radio capabilities (e.g., to reduce radio capabilities by excluding the radio capabilities of a RAT or to increase the radio capabilities) (see messaging  350 ). The UE  205  may use Registration Request message having a type of Mobility Registration Update and including an indication that radio capability change is required. This indication can be called e.g., ‘UE  205  radio capability’ or ‘UE  205  radio capability change’ or any other similar parameter name can be used. This ‘UE  205  radio capability change’ indication causes at the AMF  230  to perform the steps 6b and/or 6c. The AMF  230  may reply to the UE  205  with Registration Accept message including an appropriate cause value of accepting or rejecting the requested radio capability change. 
     In step 6b: The AMF  230  deletes the already stored UE  205  radio capabilities received previously from the NG-RAN node (see block  355 ). 
     In step 6c: The AMF  230  initiates N2 procedure to inform the NG-RAN node that the AS capabilities are changed (see messaging  360 ). The AMF  230  does not include already stored UE  205  radio capabilities. The AMF  230  may send UE  205  context to the NG-RAN node, so that the NG-RAN node can know that the AS capabilities are changed. 
     In step 6d: The NG-RAN node initiates RRC procedure to query the UE  205  radio capabilities (see messaging  365 ). The UE  205  announces/sends its radio capabilities by excluding the E-UTRA capabilities, since the AS layer has been instructed so by the NAS layer. 
     If the UE  205  is in CM/EMM Connected state and the RRC Inactive state (please note that the AMF  230  may be aware about the activation of RRC Inactive state if the AMF  230  has subscribed to RRC state notification as described in TS 23.502 clause 4.8.3 “N2 Notification procedure”) and the indication ‘UE  205  radio capability change’ is included, the AMF  230  may decide first to disable the RRC Inactive state. 
     If the UE  205  is in RM-Deregistered state, the UE  205  does not need to include ‘UE  205  radio capability’ indication, as the AMF  230  would have already deleted the previously stored UE  205  radio capabilities. The UE  205  performs normal Registration procedure with type Initial registration. 
     Step 7: The UE  205  initiates Attach procedure in the EPC/E-UTRAN system (see block  370 ). 
     Step 8: If the UE  205  is registered to another system (e.g., using DR mode and already registered to 5GS), the UE  205  announces (or sends) its AS layer capability (i.e., the E-UTRA capability) to the eNB, but the UE  205  excludes the NR radio capability (see messaging  375 ). 
     Note that steps 2-4 (grouped in the dotted line box (A)) show one solution option for explicit UE-initiated signaling for disabling the RRC Inactive state or for transition to CM Idle state. Another option is to integrate the RRC Inactive state disablement procedure in the Registration procedure for UE capability change, e.g., as shown in step 6. Also, note that  FIG.  4    shows an example signaling flow for the case where the UE  205  is registered first to the 5GS, and the UE  205  attempts a DR mode operation with EPS later. 
     For initiating EPS to 5GS dual registration case: analogically to the above, just exchanging the EPS and 5GS. In other embodiments, similar signaling flow is also applicable in the scenario where the UE  205  is first attached in the EPS and the UE  205  attempts a DR mode operation with 5GS. In such case, the UE  205  would first need to decrease its radio capabilities in the EPS, i.e., to disable the NR capability, and then the UE  205  attempts Registration procedure to the 5GS via NR. In such embodiments, UE  205  perform at least steps 2 and/or 5 towards the EPS (e.g., eNB and/or MME  235 ) to request Idle state or disable the RRC Inactive state in the E-UTRAN. 
       FIG.  4    shows a second procedure  400  for radio capability change of a UE  205 , according to embodiments of the disclosure. The second procedure  400  involves the UE  205 , an NR RAN  305 , an LTE RAN  310 , the AMF  230 , the MME  235 , a SMF+PGW-C  160 , and the HSS+UDM  225 . The steps shown in  FIG.  4    are as described follows: 
     The UE  205  sends a request to the network (e.g., an indication in NAS message to the mobility serving node (e.g., MME  235  or AMF  230 )) that a particular AS capability (e.g., RAT capability) should not be considered (i.e., the RAT capability is deprecated/disclaimed). In such case UE  205  radio capability is decreased without sending the full radio capability to the network. In similar way, the UE  205  can at any time endorse the use of the deprecated RAT capability, i.e., the UE  205  can increase its capability without sending the full radio capability, but instead abolishing/canceling previously deprecated capability. This solution may be applicable to any of the UE  205  states, e.g., CM/EMM Connected or CM/EMM Idle. 
     For example, the UE  205 , which is attached to EPS and having announces E-UTRA and NR capability to the E-UTRAN, indicates in NAS signaling to the MME  235  that the NR shall not be considered for dual connectivity. The UE  205  may trigger such signaling e.g., based on starting a DR-mode and registering with 5GS/NR. Then the MME  235  indicates to the NG-RAN node (e.g., eNB) that dual connectivity with NR shall not be configured. Upon the signaling from the MME  235 , the eNB learns that UE  205 &#39;s radio capability has not changed, but the eNB shall not consider configuring the DC with NR for this UE  205 . 
     If the UE  205  changes from DR mode to SR mode and stays attached to a first system (e.g., EPS) or other trigger events for increasing the radio capability occur, the UE  205  sends an indication in NAS signaling to the MME  235  that the deprecated RAT capability (e.g., NR capability) may be endorsed, i.e., the deprecated RAT capability can be considered for dual connectivity. With other words, the NAS signaling ‘activates’ a deprecated RAT (e.g., NR) capability. 
     Step 0: The UE  205  is registered in 5GS (see messaging  405 ). The UE  205  has indicated support of 1) NR+LTE radio capability to the NG-RAN node and 2) EPS NAS capability to the AMF  230 . 5GS can configure dual connectivity (DC). The 5GS indicates to the UE  205  the interworking without N26 is supported. 
     Step 1: The UE  205  detects LTE coverage and determines to initiate dual registration mode of operation (see block  410 ). The UE  205  decides to change radio capabilities in the currently used system, e.g., in the 5GS/NR. The UE  205  may determine that it is in CM Connected state and RRC Inactive state. 
     Step 2: The UE  205  initiates NAS procedure towards the core network (e.g., AMF  230 ) indicating that a particular AS capability (e.g., RAT capability) is deprecated (see messaging  415 ). With other words this RAT capability should not be considered for dual connectivity (DC) configuration. For example, the UE  205  may send a Registration Request message including an indication that the E-UTRA capability should not be considered in the system. 
     Step 3 a : From CN to RAN: (if the UE  205  is in CM/EMM Connected state,) the AMF  230  initiates UE  205  Context updated procedure towards the NG-RAN node to indicate that a particular UE  205  radio capability is deprecated (see messaging  420 ). For example, the AMF  230  indicates to the NG-RAN node that the NR capability is deprecated, i.e., dual connectivity with E-UTRAN should not be configured. 
     Step 3 b : After the NG-RAN node acknowledges the reception (and possibly processing of the requested to deprecate RAT capability) (see messaging  425 ). The Core network (e.g., the AMF  230 ) may respond to the registration request of step 2 by sending an appropriate cause value whether the request from step 2 is accepted or rejected. 
     Step 4: The NG-RAN node performs RRC reconfiguration to disable the UE  205  radio measurements in the indicated RAT (e.g., in the E-UTRA) (See messaging  430 ). 
     Step 5: The UE  205  initiates Attach procedure in the EPC/E-UTRAN system (see block  435 ). 
     Step 6: The UE  205  announces E-UTRA capability to the eNB, but the UE  205  excludes the NR radio capability (see block  440 ). 
     In summary, the  FIG.  5    shows a method for deprecating a particular AS capability, e.g., using NAS signaling, without the need to send the complete UE  205  radio capabilities to the network (e.g., to the RAN node). Please note that  FIG.  5    shows an example signaling flow for the case where the UE  205  is registered first to the 5GS, and the UE  205  attempts a DR mode operation with EPS later. 
     In another embodiment, it is also possible that the UE  205  abolishes the deprecated AS capability at some point, i.e., the UE  205  enables (or endorses) the deprecated AS capability. For example, the UE  205  sends a NAS message (e.g., Registration Request message or TAU request message) including an indication that a deprecated AS capability (e.g., deprecated RAT capability) should be enabled. Then the core network (e.g., MME  235  or AMF  230 ) updates the NG-RAN node via S1 or N2 interface with an indication to enable the deprecated AS capability. The NG-RAN node can perform RRC reconfiguration to configure the UE  205  to report measurements for previously deprecated RAT. 
     In another embodiment related to the  FIG.  4   , similar signaling flow is also applicable in the scenario where the UE  205  is first attached in the EPS and the UE  205  attempts a DR mode operation with 5GS. In such case, the UE  205  would first deprecate particular AS capabilities in the EPS, i.e., to disable the NR capability, and then the UE  205  attempts Registration procedure to the 5GS via NR. 
     In yet another embodiment related to the  FIG.  4   , the network may determine to deprecate a particular AS capability (e.g., RAT capability) without explicit indication by the UE  205 . For example, this can be performed including signaling exchange via HSS+UDM  225 . When a UE  205  registered to 5GS decides to use DR mode and attempts to attach to the EPS (e.g., MME  235 ), the MME  235  updates the HSS+UDM  225  indicating that the UE  205  is attaching for DR mode of operation. The HSS+UDM  225  informs the AMF  230  that the UE  205  is now in addition attached to the EPS. Then the AMF  230  initiates signaling towards the NG-RAN node (e.g., gNB) to indicate that the E-UTRA capability is deprecated. The AMF  230  assumes that the UE  205  has sent E-UTRA capability to gNB because the E-UTRA is a native RAT in NG-RAN. 
     In certain embodiments, the UE  205  may determine to not send radio measurement reports to the NG-RAN node including measurements from a RAT which the UE  205  uses in another system. For example, if the UE  205  has announced NR capabilities to the E-UTRAN node and the UE  205  is configured to perform measurements of NR cell, and the UE  205  is in DR mode with the 5GC/NR, the UE  205  determines to not report radio measurements of NR cell even if the UE  205  can measure signal from NR cell. This can be done by either signaling some special or reserved values; that indicate to the network that the UE  205  is neither measuring NR cell nor is it interested in being handed over to NR cell; or, by not making any measurements at all. In any case, the UE  205  shall report only especial or Zero signal level (Reference Signal Received Power (“RSRP”), for example) if periodic reporting is configured. The UE  205  may reject measurement gaps configured for such purposes. Alternatively, a UE  205  may directly indicate to the RAN network that it is not interested in measuring or being handed over to an NR cell, by way of a new RRC signaling just for example. 
     In certain embodiments, if the UE  205  is operating in DR mode, but the UE  205  is only attached/registered with the first system (e.g., 5GS) without established PDN connection or PDU Session, then the UE  205  continues to use its dual radio capabilities, i.e., the UE  205  uses the first system radio capability (e.g., NR capabilities) to the second system (e.g., EPS). Before the UE  205  initiates PDN connection establishment or PDU Session establishment in the first system, the UE  205  performs radio capability update procedure in the second system in order to exclude the radio capabilities of the first system (e.g., exclude NR capability). 
     Please note that the use cases for triggering radio capability change can be various. In some embodiments the assumption is the enablement or disablement of DR mode, however other use cases are possible. For example, the modem capabilities (e.g., mobile equipment (ME) capability) changes due to hardware modification like attaching or detaching hardware to the terminal. Another example is that the user can enable or disable terminal capability via the phone&#39;s menu. 
       FIG.  5    depicts a user equipment apparatus  500  that may be used for UE power control for multiple UL carriers, according to embodiments of the disclosure. The user equipment apparatus  500  may be one embodiment of the remote unit  105  and/or UE  205 , described above. Furthermore, the user equipment apparatus  500  may include a processor  505 , a memory  510 , an input device  515 , an output device  520 , a transceiver  525  for communicating with one or more base units  110 . 
     As depicted, the transceiver  525  may include a transmitter  530  and a receiver  535 . The transceiver  525  may also support one or more network interfaces  540 , such as the Uu interface used to communicate with a gNB, or another suitable interface for communicating with a RAN (e.g., first access network  120  and/or second access network  125 ). In some embodiments, the input device  515  and the output device  520  are combined into a single device, such as a touchscreen. In certain embodiments, the user equipment apparatus  500  may not include any input device  515  and/or output device  520 . 
     The processor  505 , in one embodiment, may include any known controller capable of executing computer-readable instructions and/or capable of performing logical operations. For example, the processor  505  may be a microcontroller, a microprocessor, a central processing unit (“CPU”), a graphics processing unit (“GPU”), an auxiliary processing unit, a field programmable gate array (“FPGA”), or similar programmable controller. In some embodiments, the processor  505  executes instructions stored in the memory  510  to perform the methods and routines described herein. The processor  505  is communicatively coupled to the memory  510 , the input device  515 , the output device  520 , and the transceiver  525 . 
     In various embodiments, the processor  505  registers with a first communication system via the RAN node. In some embodiments, registering with the first communication system includes indicating one or more UE radio capabilities for at least one RAT to the first communication system. 
     The processor  505  detects a trigger to perform radio capability change for at least one radio access technology (“RAT”). In some embodiments, detecting a trigger to perform radio capability change includes determining to perform dual-registration with a second communication system. In some embodiments, detecting a trigger to perform radio capability change includes determining to register with a second communication system, the second system different than the first system. In certain embodiments, the first and second communication systems belonging to the same PLMN. In certain embodiments, the first communication system includes an EPC and wherein the second communication system includes a 3GPP fifth generation core network. 
     The processor  505  transitions the UE state of the user equipment apparatus  500  to an idle state. In various embodiments, transitioning the UE state to an idle state includes entering a Connection Management (“CM”) Idle state on the NAS layer. In such embodiments, a NAS entity instructs a UE Access Stratum (“AS”) entity to discard/deactivate the existing AS context and instructs the UE AS entity to modify an AS layer capability for the user equipment apparatus  500  in response to entering the CM Idle state. In certain embodiments, modifying the AS layer capability includes disabling a UE capability for a particular radio access technology. In certain embodiments, modifying the AS layer capability includes enabling a UE capability for a particular radio access technology. In certain embodiments, entering the CM Idle state includes deactivating the AS context to enter a radio resource control (“RRC”) idle state using, e.g., NAS signaling and/or RRC signaling. 
     The processor  505  requests the network (e.g., the first communication system) to update one or more UE radio capabilities while in the idle state. In some embodiments, requesting to update one or more UE radio capabilities includes performing a radio capability exchange towards the RAN node. 
     In various embodiments, requesting to update one or more UE radio capabilities includes using a NAS signaling procedure to indicate the update of one or more UE radio capabilities. In one embodiment, requesting to update one or more UE radio capabilities includes sending a NAS registration request. Here, the NAS registration has a mobility registration type and indicates the updated one or more UE radio capabilities. In another embodiment, requesting to update one or more UE radio capabilities includes sending a tracking area update (“TAU”) request. Here, the TAU request indicates the updated one or more UE radio capabilities. 
     In some embodiments, detecting a trigger to perform radio capability change includes detecting a need to change an Access Stratum (“AS”) capability of the user equipment apparatus  500 . In such embodiments, requesting to update one or more UE radio capabilities includes requesting that a particular AS capability be deprecated, wherein the RAN node does not consider the particular AS capability. In certain embodiments, requesting that a particular AS capability be deprecated includes sending one of a NAS message and an RRC message to a core network. 
     In certain embodiments, requesting that a particular AS capability be deprecated includes indicating that a previously indicated RAT capability is deprecated. In certain embodiments, requesting that a particular AS capability be deprecated includes indicating that the core network does not need to update the UE radio capability. In some embodiments, detecting the need to change the AS capability of the user equipment apparatus  500  includes determining to register with a second communication system. In certain embodiments, the processor  505  further sends a request to the network to abolish the deprecated AS capability. 
     The memory  510 , in one embodiment, is a computer readable storage medium. In some embodiments, the memory  510  includes volatile computer storage media. For example, the memory  510  may include a RAM, including dynamic RAM (“DRAM”), synchronous dynamic RAM (“SDRAM”), and/or static RAM (“SRAM”). In some embodiments, the memory  510  includes non-volatile computer storage media. For example, the memory  510  may include a hard disk drive, a flash memory, or any other suitable non-volatile computer storage device. In some embodiments, the memory  510  includes both volatile and non-volatile computer storage media. 
     In some embodiments, the memory  510  stores data related to modifying a radio capability. For example, the memory  510  may store radio capabilities, registrations, and the like. In certain embodiments, the memory  510  also stores program code and related data, such as an operating system or other controller algorithms operating on the remote unit  105 . 
     The input device  515 , in one embodiment, may include any known computer input device including a touch panel, a button, a keyboard, a stylus, a microphone, or the like. In some embodiments, the input device  515  may be integrated with the output device  520 , for example, as a touchscreen or similar touch-sensitive display. In some embodiments, the input device  515  includes a touchscreen such that text may be input using a virtual keyboard displayed on the touchscreen and/or by handwriting on the touchscreen. In some embodiments, the input device  515  includes two or more different devices, such as a keyboard and a touch panel. 
     The output device  520 , in one embodiment, is designed to output visual, audible, and/or haptic signals. In some embodiments, the output device  520  includes an electronically controllable display or display device capable of outputting visual data to a user. For example, the output device  520  may include, but is not limited to, a Liquid Crystal Display (“LCD”), a Light-Emitting Diode (“LED”) display, an Organic LED (“OLED”) display, a projector, or similar display device capable of outputting images, text, or the like to a user. As another, non-limiting, example, the output device  520  may include a wearable display separate from, but communicatively coupled to, the rest of the user equipment apparatus  500 , such as a smart watch, smart glasses, a heads-up display, or the like. Further, the output device  520  may be a component of a smart phone, a personal digital assistant, a television, a table computer, a notebook (laptop) computer, a personal computer, a vehicle dashboard, or the like. 
     In certain embodiments, the output device  520  includes one or more speakers for producing sound. For example, the output device  520  may produce an audible alert or notification (e.g., a beep or chime). In some embodiments, the output device  520  includes one or more haptic devices for producing vibrations, motion, or other haptic feedback. In some embodiments, all or portions of the output device  520  may be integrated with the input device  515 . For example, the input device  515  and output device  520  may form a touchscreen or similar touch-sensitive display. In other embodiments, the output device  520  may be located near the input device  515 . 
     The transceiver  525  includes at least transmitter  530  and at least one receiver  535 . One or more transmitters  530  may be used to provide UL communication signals to a base unit  110 . Similarly, one or more receivers  535  may be used to receive DL communication signals from the base unit  110 , as described herein. Although only one transmitter  530  and one receiver  535  are illustrated, the user equipment apparatus  500  may have any suitable number of transmitters  530  and receivers  535 . Further, the transmitter(s)  530  and the receiver(s)  535  may be any suitable type of transmitters and receivers. In one embodiment, the transceiver  525  includes a first transmitter/receiver pair used to communicate with a mobile communication network over licensed radio spectrum and a second transmitter/receiver pair used to communicate with a mobile communication network over unlicensed radio spectrum. 
     As discussed above, the transceiver  525  communicates with one or more network functions of a mobile communication network via one or more access networks. The transceiver  525  operates under the control of the processor  505  to transmit messages, data, and other signals and also to receive messages, data, and other signals. For example, the processor  505  may selectively activate the transceiver (or portions thereof) at particular times in order to send and receive messages. The transceiver  525  may include one or more transmitters  530  and one or more receivers  535 . In certain embodiments, the one or more transmitters  530  and/or the one or more receivers  535  may share transceiver hardware and/or circuitry. For example, the one or more transmitters  530  and/or the one or more receivers  535  may share antenna(s), antenna tuner(s), amplifier(s), filter(s), oscillator(s), mixer(s), modulator/demodulator(s), power supply, and the like. 
     In various embodiments, the transceiver  525  is configured to communication with 3GPP access network(s) and/or non-3GPP access network(s). In some embodiments, the transceiver  525  implements modem functionality for the 3GPP access network(s) and/or the non-3GPP access network(s). In one embodiment, the transceiver  525  comprises a chip that implements multiple logical transceivers using different communication protocols or protocol stacks, while using common physical hardware. For example, the transceiver  525  may include one application-specific integrated circuit (“ASIC”) which includes the function of first transceiver and second transceiver for accessing networks of different RATs. In other embodiments, the transceiver  525  comprises separate transceiver hardware for accessing networks of different RATs. 
       FIG.  6    is a schematic flow chart diagram illustrating one embodiment of a method  600  for modifying a radio capability, according to embodiments of the disclosure. In some embodiments, the method  600  is performed by a UE, such as the remote unit  105 , the UE  205 , and/or the user equipment apparatus  500 . In certain embodiments, the method  600  may be performed by a processor executing program code, for example, a microcontroller, a microprocessor, a CPU, a GPU, an auxiliary processing unit, a FPGA, or the like. 
     The method  600  includes registering  605  with a first communication system via a radio access network (“RAN”) node. In some embodiments, registering with the first communication system includes indicating one or more UE radio capabilities for at least one RAT to the first communication system. 
     The method  600  includes detecting  610  a trigger to perform radio capability change for at least one radio access technology (“RAT”). In some embodiments, detecting  610  a trigger to perform radio capability change includes determining to register with a second communication system, the second system different than the first system. In certain embodiments, the first and second communication systems belonging to the same PLMN. In certain embodiments, the first communication system includes an EPC and wherein the second communication system includes a 3GPP fifth generation core network. 
     The method  600  includes transitioning  615  the UE state to an idle state. In various embodiments, transitioning  615  the UE state to an idle state includes entering a Connection Management (“CM”) Idle state on the NAS layer entity of the UE. In certain embodiments, entering the CM Idle state includes deactivating the AS context (e.g., using NAS signaling or RRC signaling) to enter an RRC idle state. 
     The method  600  includes sending  620  a request to the network to update one or more UE radio capabilities while in the idle state. The method  600  ends. In some embodiments, sending  620  the request to update one or more UE radio capabilities includes using a NAS signaling procedure to indicate the update of one or more UE radio capabilities. In one embodiment, sending  620  the request to update one or more UE radio capabilities includes sending a NAS registration request, said request having a mobility registration type and indicating the updated one or more UE radio capabilities. In another embodiment, sending  620  the request to update one or more UE radio capabilities includes sending a tracking area update request, said request indicating the updated one or more UE radio capabilities. 
     In certain embodiments, detecting  610  a trigger to perform radio capability change includes determining to perform dual-registration with a second communication system. In such embodiments, sending  620  the request to update one or more UE radio capabilities includes performing a radio capability exchange towards the RAN node. 
     In some embodiments, detecting  610  a trigger to perform radio capability change includes detecting a need to change an Access Stratum (“AS”) capability of the UE, wherein sending  620  the request to update one or more UE radio capabilities includes requesting that a particular AS capability be deprecated, wherein the RAN node does not consider the particular AS capability. In certain embodiments, detecting the need to change the AS capability of the UE includes determining to register with a second communication system. 
     In certain embodiments, requesting that a particular AS capability be deprecated includes sending a NAS message or an RRC message to a core network. In certain embodiments, requesting that a particular AS capability be deprecated includes indicating that a previously indicated RAT capability is deprecated. In certain embodiments, requesting that a particular AS capability be deprecated includes indicating that the core network does not need to update the UE radio capability. 
       FIG.  7    is a schematic flow chart diagram illustrating one embodiment of a method  700  for modifying a radio capability, according to embodiments of the disclosure. In some embodiments, the method  700  is performed by a UE, such as the remote unit  105 , the UE  205 , and/or the user equipment apparatus  500 . In certain embodiments, the method  700  may be performed by a processor executing program code, for example, a microcontroller, a microprocessor, a CPU, a GPU, an auxiliary processing unit, a FPGA, or the like. 
     The method  700  includes determining  705  that an update of a radio access capability for a first radio access technology is required based at least in part on whether to use a second radio access technology. The method  700  includes switching  710  to an idle state based on determining that the update of the radio access capability for the first radio access technology is required. The method  700  includes transmitting  715  a request message indicating that the update of the radio access capability for the first radio access technology is required in response to switching to the idle state, the request message further indicating to delete a stored radio access capability associated with the UE and obtain a new radio access capability associated with the UE. The method  700  ends. 
       FIG.  8    is a schematic flow chart diagram illustrating one embodiment of a method  800  for modifying a radio capability, according to embodiments of the disclosure. In some embodiments, the method  800  is performed by a mobility management function, such as the AMF  135 , the AMF  230 , and/or the MIME  235 . In certain embodiments, the method  800  may be performed by a processor executing program code, for example, a microcontroller, a microprocessor, a CPU, a GPU, an auxiliary processing unit, a FPGA, or the like. 
     The method  800  includes receiving  805 , from a UE, a first message indicating an updated radio access capability. The method  800  includes deleting  810  a radio access capability associated with the UE based at least in part on the received first message. The method  800  includes transmitting  815 , to a second network entity, a second message excluding the radio access capability associated with the UE. The method  800  includes receiving  820 , from the second network entity, a third message indicating a new radio access capability associated with the UE. The method  800  ends. 
     Disclosed herein is a first apparatus for modifying a radio capability. The first apparatus may be implemented by the remote unit  105 , the UE  205 , and/or the user equipment apparatus  500 . The first apparatus includes a processor and a transceiver that communicates with a RAN node. The processor registers with a first communication system via the RAN node. The processor detects a trigger to perform radio capability change for at least one radio access technology (“RAT”) and transitions a UE state of the apparatus to an idle state. The processor further sends a request to the first communication system to update one or more UE radio capabilities while in the idle state. 
     In some embodiments, registering with the first communication system includes indicating one or more UE radio capabilities for at least one RAT to the first communication system. In some embodiments, detecting a trigger to perform radio capability change includes determining to perform dual-registration with a second communication system. In such embodiments, sending the request to update one or more UE radio capabilities includes performing a radio capability exchange towards the RAN node, wherein the processor updates one or more UE radio access technology capabilities of the second communication system during the radio capability exchange. 
     In various embodiments, sending the request to update one or more UE radio capabilities includes using a NAS signaling procedure to indicate the update of one or more UE radio capabilities. In one embodiment, sending the request to update one or more UE radio capabilities includes sending a NAS registration request. Here, the NAS registration has a mobility registration type and indicates the updated one or more UE radio capabilities. In another embodiment, sending the request to update one or more UE radio capabilities includes sending a tracking area update (“TAU”) request. Here, the TAU request indicates the updated one or more UE radio capabilities. 
     In some embodiments, detecting a trigger to perform radio capability change includes determining to register with a second communication system, the second system different than the first system. In certain embodiments, the first and second communication systems belonging to the same PLMN. In certain embodiments, the first communication system includes an EPC and wherein the second communication system includes a 3GPP fifth generation core network. 
     In various embodiments, transitioning the UE state to an idle state includes entering a Connection Management (“CM”) Idle state on the NAS layer. In such embodiments, the first apparatus includes a NAS entity that instructs a UE Access Stratum (“AS”) entity to discard (or deactivate) the existing AS context and instructs the UE AS entity to modify an AS layer capability for the apparatus in response to entering the CM Idle state. In certain embodiments, modifying the AS layer capability includes disabling a UE capability for a particular radio access technology. In certain embodiments, modifying the AS layer capability includes enabling a UE capability for a particular radio access technology. In certain embodiments, entering the CM Idle state includes deactivating the AS context to enter a radio resource control (“RRC”) idle state using, e.g., NAS signaling and/or RRC signaling. 
     In some embodiments, detecting a trigger to perform radio capability change includes detecting a need to change an Access Stratum (“AS”) capability of the apparatus. In such embodiments, sending the request to update one or more UE radio capabilities includes requesting that a particular AS capability be deprecated, wherein the RAN node does not consider the particular AS capability. In certain embodiments, requesting that a particular AS capability be deprecated includes sending wither a NAS message or an RRC message to a core network. 
     In certain embodiments, requesting that a particular AS capability be deprecated includes indicating that a previously indicated RAT capability is deprecated. In certain embodiments, requesting that a particular AS capability be deprecated includes indicating that the core network does not need to update the UE radio capability. In some embodiments, detecting the need to change the AS capability of the apparatus includes determining to register with a second communication system. In certain embodiments, the processor further sends a request to the network to abolish the deprecated AS capability. 
     Disclosed herein is a first method for modifying a radio capability. The first method may be performed by a UE, such as the remote unit  105 , the UE  205 , and/or the user equipment apparatus  500 . The first method includes registering with a first communication system via a radio access network (“RAN”) node and detecting a trigger to perform radio capability change for at least one radio access technology (“RAT”). The first method includes transitioning a UE state to an idle state and sending a request to the first communication system to update one or more UE radio capabilities while in the idle state. 
     In some embodiments, registering with the first communication system includes indicating one or more UE radio capabilities for at least one RAT to the first communication system. In certain embodiments, detecting a trigger to perform radio capability change includes determining to perform dual-registration with a second communication system. In such embodiments, sending the request to update one or more UE radio capabilities includes performing a radio capability exchange towards the RAN node. Here, the first method may also include updating one or more UE radio access technology capabilities of the second communication system during the radio capability exchange. 
     In some embodiments, sending the request to update one or more UE radio capabilities includes using a NAS signaling procedure to indicate the update of one or more UE radio capabilities. In one embodiment, sending the request to update one or more UE radio capabilities includes sending a NAS registration request, said request having a mobility registration type and indicating the updated one or more UE radio capabilities. In another embodiment, sending the request to update one or more UE radio capabilities includes sending a tracking area update request, said request indicating the updated one or more UE radio capabilities. 
     In some embodiments, detecting a trigger to perform radio capability change includes determining to register with a second communication system, the second system different than the first system. In certain embodiments, the first and second communication systems belonging to the same PLMN. In certain embodiments, the first communication system includes an EPC and wherein the second communication system includes a 3GPP 5GC. 
     In various embodiments, transitioning to an idle state includes entering a Connection Management (“CM”) Idle state on the NAS layer of the UE. In such embodiments, the first method may include a NAS entity instructing a UE Access Stratum (“AS”) entity to discard/deactivate the existing AS context and instructing the UE AS entity to modify an AS layer capability for the UE in response to entering the CM Idle state. In certain embodiments, modifying the AS layer capability includes disabling a UE capability for a particular radio access technology. In certain embodiments, modifying the AS layer capability includes enabling a UE capability for a particular radio access technology. In certain embodiments, entering the CM Idle state includes deactivating the AS context to enter a radio resource control (“RRC”) idle state using, e.g., NAS signaling and/or RRC signaling. 
     In some embodiments, detecting a trigger to perform radio capability change includes detecting a need to change an Access Stratum (“AS”) capability of the UE, wherein sending the request to update one or more UE radio capabilities includes requesting that a particular AS capability be deprecated, wherein the RAN node does not consider the particular AS capability. In certain embodiments, detecting the need to change the AS capability of the UE includes determining to register with a second communication system. Here, the first method may include sending a request to the network to abolish the deprecated AS capability. 
     In certain embodiments, requesting that a particular AS capability be deprecated includes sending a NAS message or an RRC message to a core network. In certain embodiments, requesting that a particular AS capability be deprecated includes indicating that a previously indicated RAT capability is deprecated. In certain embodiments, requesting that a particular AS capability be deprecated includes indicating that the core network does not need to update the UE radio capability. 
     Disclosed herein is a first method for modifying a radio capability. The first method may be performed by a UE, such as the remote unit  105 , the UE  205 , and/or the user equipment apparatus  500 . The first method includes a memory and a processor coupled to the memory, the processor configured to cause the apparatus to: A) determine that an update of a radio access capability for a first radio access technology is required based at least in part on whether to use a second radio access technology; B) switch to an idle state based on the determination that the update of the radio access capability for the first radio access technology is required; and C) transmit a request message indicating that the update of the radio access capability for the first radio access technology is required in response to the switch to the idle state, the request message further indicating to delete a stored radio access capability associated with the apparatus and obtain a new radio access capability associated with the apparatus. 
     In some embodiments, to determine that the update of the radio access capability for the first radio access technology is required, the processor is configured to cause the apparatus to determine whether the apparatus is operating concurrently in accordance with the first radio access technology and the second radio access technology. 
     In some embodiments, to transmit the request message indicating that the update of the radio access capability for the first radio access technology is required, the processor is configured to cause the apparatus to transmit the request message using a non-access stratum procedure. In such embodiments, the request message includes a non-access stratum request message. 
     In some embodiments, to transmit the request message indicating that the update of the radio access capability for the first radio access technology is required, the processor is configured to cause the apparatus to transmit a tracking area update request indicating that the update of the radio access capability for the first radio access technology is required. 
     In some embodiments, the processor is configured to cause the apparatus to register with a first communication system using the first radio access technology. In certain embodiments, to determine that the update of the radio access capability for the first radio access technology is required, the processor is configured to cause the apparatus to determine whether the registered first communication system supports a service for the apparatus. 
     In some embodiments, to determine that the update of the radio access capability for the first radio access technology is required, the processor is configured to cause the apparatus to detect a trigger that the update of the radio access capability for the first radio access technology is required. In such embodiments, the trigger includes that a service for the apparatus is unsupported by the registered first communication system. 
     In certain embodiments, the processor is configured to cause the apparatus to register with a second communication system based on the determination that the update of the radio access capability for the first radio access technology is required. In further embodiments, the first communication system is different than the second communication system. In some embodiments, to register with the first communication system, the processor is configured to cause the apparatus to transmit an indication of one or more radio access capabilities associated with the apparatus. 
     Disclosed herein is a second method for modifying a radio capability. The second method may be performed by a UE, such as the remote unit  105 , the UE  205 , and/or the user equipment apparatus  500 . The second method includes determining that an update of a radio access capability for a first radio access technology is required based at least in part on whether to use a second radio access technology. The second method includes switching to an idle state based on determining that the update of the radio access capability for the first radio access technology is required and transmitting a request message indicating that the update of the radio access capability for the first radio access technology is required in response to switching to the idle state, the request message further indicating to delete a stored radio access capability associated with the UE and obtain a new radio access capability associated with the UE. 
     In some embodiments, determining that the update of the radio access capability for the first radio access technology is required includes determining whether the UE is operating concurrently in accordance with the first radio access technology and the second radio access technology. 
     In some embodiments, transmitting the request message indicating that the update of the radio access capability for the first radio access technology is required includes transmitting the request message using a non-access stratum procedure. In such embodiments, the request message may include a non-access stratum request message. 
     In some embodiments, transmitting the request message indicating that the update of the radio access capability for the first radio access technology is required includes transmitting a tracking area update request indicating that the update of the radio access capability for the first radio access technology is required. 
     In some embodiments, the second method further includes registering with a first communication system using the first radio access technology. In certain embodiments, determining that the update of the radio access capability for the first radio access technology is required includes determining whether the registered first communication system supports a service for the UE. 
     In some embodiments, determining that the update of the radio access capability for the first radio access technology is required includes detecting a trigger that the update of the radio access capability for the first radio access technology is required. In such embodiments, the trigger includes that a service for the UE is unsupported by the registered first communication system. 
     In certain embodiments, the second method further includes registering with a second communication system based on determining that the update of the radio access capability for the first radio access technology is required. In further embodiments, the first communication system is different than the second communication system. In some embodiments, registering with the first communication system includes transmitting an indication of one or more radio access capabilities associated with the UE. 
     Disclosed herein is a third apparatus for modifying a radio capability. The third apparatus may be implemented by a mobility management function, such as the AMF  135 , the AMF  230 , and/or the MME  235 . The third apparatus includes a memory and a processor coupled to the memory, where the processor is configured to: A) receive, from a UE, a first message indicating an updated radio access capability; B) delete a radio access capability associated with the UE based at least in part on the received first message; C) transmit, to a network entity, a second message excluding the radio access capability associated with the UE; and D) receive, from the network entity, a third message indicating a new radio access capability associated with the UE. 
     In some embodiments, the processor is configured to cause the apparatus to transmit, to the UE, a fourth message comprising a cause value that indicates acceptance of the updated radio access capability indicated in the first message. In certain embodiments, the first message comprises a registration request message having a mobility registration type and the fourth message comprises a registration accept message. 
     In certain embodiments, the first message and the fourth message are part of a NAS procedure between the third apparatus and the UE, and the second message and the third message are part of a N2 procedure between the third apparatus and the network entity. In some embodiments, the first message comprises a tracking area update request. 
     In some embodiments, the first message is received while the UE is in an idle state. In some embodiments, the processor is configured to cause the apparatus to transition a UE state associated with the UE to an idle state prior to receipt of the first message. In some embodiments, the first message comprises an indication to delete a radio access capability associated with the UE. 
     In some embodiments, to transmit the second message, the processor is configured to cause the apparatus to initiate an N2 procedure informing the network entity that an AS capability associated with the UE is changed. Here, the network entity may be a RAN node, such as the base unit  110 , the NG-RAN node (e.g., gNB), or the like. In some embodiments, the second message comprises a UE context associated with the UE. 
     In some embodiments, the processor is configured to cause the apparatus to store the new radio access capability associated with the UE. In some embodiments, the radio access capability comprises a capability associated with a specific RAT supported by the UE and wherein, for each RAT, the radio access capability comprises a supported frequency band. 
     Disclosed herein is a third method for modifying a radio capability. The third method may be performed by a first network entity, such as the AMF  135 , the AMF  230 , and/or the MME  235 . The third method includes receiving, from a UE, a first message indicating an updated radio access capability and deleting a radio access capability associated with the UE based at least in part on the received first message. The third method includes transmitting, to a second network entity, a second message excluding the radio access capability associated with the UE and receiving, from the second network entity, a third message indicating a new radio access capability associated with the UE. 
     In some embodiments, the third method includes transmitting, to the UE, a fourth message comprising a cause value that indicates acceptance of the updated radio access capability. In certain embodiments, the first message comprises a registration request message having a mobility registration type and the fourth message comprises a registration accept message. 
     In certain embodiments, the first message and the fourth message are part of a NAS procedure between the first network entity and the UE, and the second message and the third message are part of a N2 procedure between the first network entity and the second network entity. In some embodiments, the first message comprises a tracking area update request. 
     In some embodiments, the first message is received while the UE is in an idle state. In some embodiments, third method includes transitioning a UE state associated with the UE to an idle state prior to receipt of the first message. In some embodiments, the first message comprises an indication to delete a radio access capability associated with the UE. 
     In some embodiments, transmitting the second message comprises initiating an N2 procedure informing the second network entity that an AS capability associated with the UE is changed. Here, the second network entity may be a RAN node, such as the base unit  110 , the NG-RAN node (e.g., gNB), or the like. In some embodiments, the second message comprises a UE context associated with the UE. 
     In some embodiments, the third method includes storing the new radio access capability associated with the UE. In some embodiments, the radio access capability comprises a capability associated with a specific RAT supported by the UE and wherein, for each RAT, the radio access capability comprises a supported frequency band. 
     Embodiments may be practiced in other specific forms. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.