IMS re-registration during ongoing mmtel sessions or smsoip in 5g network

Abstract

A user equipment (UE) is configured to decode an internet protocol (IP) multimedia subsystem (IMS) registration response including a timer value for IMS registration validity, start a timer with the timer value, prior to the timer expiring, initiate a registration with the IMS, when at least one service of a group of services is ongoing over IMS, skip an access check for IMS registration and configure transceiver circuitry to transmit an IMS registration request without performing the access check for IMS registration.

Description

IMS Re-Registration During Ongoing MMTEL Sessions or SMSoIP in 5G NetworkInventors: Nirlesh Koshta, Krisztian Kiss, Pradeep Pangi, Robert Zaus, Roland Gruber and Sridhar PrakasamBackground

[0001] A user equipment (UE) may connect to a fifth generation (5G) core network via a 5G new radio (NR) network. Prior to receiving certain Internet Protocol (IP) based services, e.g., multimedia telephony (MMTel) services or short messaging service (SMS) over IP (SMSoIP) , the UE registers with the IP Multimedia Subsystem (IMS) . The IMS registration procedure includes the transmission of a registration request by the UE and the reception of a registration response. If the IMS registration is successful, the UE can receive in the registration response a timer value indicating a duration within which the UE is to re-register with the IMS. If the UE does not re-register with the IMS before the expiration of the timer, then the IMS can de-register the UE . In another procedure, the UE can subscribe for a registration-state event package by transmitting a SUBSCRIBE request and receiving a NOTIFY request in response. The NOTIFY request may include a timer value indicating a duration within which the UE is to refresh the subscription .

[0002] Access control generally refers to a congestion control method for preventing access to a network for certain types of traffic. An access check may be performed at the UE prior to requesting access to the network or initiating the signaling for a service. The access check may comprise reading access parameters from a subscriber identification module (SIM) , determining a type of access attempt, drawing a random number'rand' from the interval 0 < 'rand' < 1 and checking these parameters (or parameters derived therefrom) against access barring information broadcast by the network. If the access check fails, then the UE does not transmit the request to access the network or the request for the specific service.

[0003] In Rel-16, a new access category was added for the IMS registration service for differentiating IMS session initiation protocol (SIP) registration traffic (e.g. , SIP signaling) and registration-state event package subscription traffic from multimedia services over IMS, e.g. , MMTel voice, MMTel video, and / or SMSoIP, and other services based on normal packet switched (PS) data traffic over IMS. However, this has resulted in some cases where the UE does not perform IMS registration before the registration validity timer expires. If the UE fails to re-register before the expiration of the timer, and an MMTel or SMSoIP session is ongoing, the de-registration of the UE by the IMS may result in an abrupt termination of the service.Summary

[0004] Some exemplary aspects are related to an apparatus of a user equipment (UE) having processing circuitry configured to decode an internet protocol (IP) multimedia subsystem (IMS) registration response including a timer value for IMS registration validity, start a timer with the timer value, prior to the timer expiring, initiate a registration with the IMS, when at least one service of a group of services is ongoing over IMS, skip an access check for IMS registration and configure transceiver circuitry to transmit an IMS registration request without performing the access check for IMS registration.

[0005] Other exemplary embodiments are related to an apparatus of a user equipment (UE ) having processing circuitry configured to decode an internet protocol ( IP ) multimedia subsystem ( IMS ) NOTI FY request including a timer value for subscription validity, start a timer with the timer value , prior to the timer expiring, initiate a subscription refresh, when at least one service of a group of services is ongoing over IMS , skip an access check for transmitting a SUBSCRIBE request and configure transceiver circuitry to transmit the SUBSCRIBE request without performing the access check for the SUBSCRIBE request .

[0006] Still further exemplary embodiments are related to a method performed by an internet protocol ( IP) multimedia subsystem ( IMS ) entity, the method including transmitting an IMS registration response to a user equipment (UE ) including a timer value for IMS registration validity, starting a timer with the timer value and when the timer expires while the UE has at least one service of a group of services ongoing over IMS , delaying a deregistration of the UE until the service is inactive .Brief Description of the Drawings

[0007] Fig . 1 shows a diagram for access control according to various exemplary embodiments .

[0008] Fig . 2a shows a table for mapping an access identity and access category to an RRC establishment cause according to existing speci fication .

[0009] Fig . 2b shows a table for mapping an access attempt to an access category according to existing speci fication .

[0010] Fig. 3 shows a signaling diagram of a scenario in which IMS re-registration fails during an MMTEL voice session, an MMTEL video session or a SMS over IP session due to an access check failure according to one example.

[0011] Fig. 4 shows a signaling diagram for IMS reregistration including skipping an access check during an MMTEL voice session, an MMTEL video session or a SMS over IP session according to various exemplary embodiments.

[0012] Fig. 5 shows a network arrangement according to various exemplary embodiments.

[0013] Fig. 6 shows an exemplary UE according to various exemplary embodiments.Detailed Description

[0014] The exemplary aspects may be further understood with reference to the following description and the related appended drawings, wherein like elements are provided with the same reference numerals. The exemplary aspects describe operations for a user equipment (UE) to register with the Internet Protocol (IP) Multimedia Subsystem (IMS) in view of access control considerations. In particular, the exemplary aspects relate to IMS registration (re-registration) before the expiration of an IMS registration validity timer. In some cases, the UE may fail an internal access check (access barred) for transmitting IMS registration signaling and consequently will not re-register with the IMS prior to the expiration of the timer. If the IMS de-registers the UE prior to receiving the registration request (re-registration request) , and the UE has an active multimediatelephony (MMTel) service or short messaging service (SMS) over IP (SMSoIP) , the de-registration will cause an abrupt termination of the service. In one aspect of these exemplary embodiments, the UE can skip the access check while the MMTel and / or SMSoIP service is ongoing. In another aspect of these exemplary embodiments, the IMS can delay the de-registration of the UE while the MMTel and / or SMSoIP service is ongoing.

[0015] The exemplary aspects are described with regard to a UE . However, the use of a UE is provided for illustrative purposes. The exemplary aspects may be utilized with any electronic component that may establish a connection with a network and is configured with the hardware, software, and / or firmware to exchange information and data with the network. Therefore, the UE as described herein is used to represent any electronic component that is capable of accessing IMS services.

[0016] The exemplary embodiments are also described with regard to a fifth generation (5G) New Radio (NR) network and a next generation node B (gNB) connected to a 5G core network. However, reference to a 5G NR network and a gNB is merely provided for illustrative purposes. The exemplary embodiments may also be utilized with an Evolved Universal Terrestrial Radio Access (E-UTRA) network and a next generation evolved node B(ng-eNB) connected to a 5G core network, or with any appropriate type of network and base station including further evolutions of the cellular standards, e.g., 6G networks.

[0017] The Internet Protocol (IP) Multimedia Subsystem (IMS) refers to an architecture for providing multimedia services using the IP protocol. Multimedia telephony (MMTel) services, e.g., MMTel voice and MMTel video, and text services, e.g.,short messaging service (SMS) over IP (SMSoIP) , are based on IMS. Voice calls in 5G networks are possible over IMS. MMTel voice / video is one of the preferred ways for users to communicate with other users and, in some regions, MMTel voice / video is the only way for users to communicate.

[0018] IMS registration is required for a UE to establish IP services. The Session Initiation Protocol (SIP) refers to a signaling protocol used in the IMS registration processes. A UE can transmit an IMS registration request to a base station (e.g., gNB) , which forwards the request to the IMS via a user plane function (UPF) in the core network. A call session control function (CSCE) refers to a SIP server or proxy used to process SIP signaling and facilitate SIP registration processes in the IMS. A proxy CSCF (P-CSCF) refers to a SIP proxy server located in either a visited network or the home network that serves as a first point of contact for a UE for SIP traffic. A serving CSCF (S-CSCF) refers to a SIP server located in the home network that accesses subscriber profile information for handling SIP registration processes. These entities of the IMS core network may be referred to herein collectively as the S / P- CSCF. An interrogating CSCF (I-CSCF) refers to a SIP function that enables requests to be routed from the P-CSCF to the correct S-CSCF. The S-CSCF performs authentication of the IMS registration request and may either reject the registration request in a registration response (e.g. , 401 Unauthorized) or indicate successful registration in a registration response (e.g. , 200 OK) .

[0019] The UE receives a timer value in the registration response (e.g., 200 OK) message from the IMS core network. The timer value indicates a duration for which the IMS registrationis valid and may be referred to herein as a registration validity timer. The registration validity timer is maintained at both the UE and the IMS core network. Prior to the expiration of the timer, the UE can attempt to re-register with the IMS core network by transmitting another registration request. If the re-registration attempt is received by the IMS core network prior to the expiration of the timer, the IMS core network can accept the request and provide another registration validity timer value to the UE for the updated IMS registration. If the re-registration attempt is not received by the IMS core network prior to the expiration of the timer, the IMS core network can initiate a de-registration of the UE for IMS services .

[0020] Another IMS registration-related signaling procedure is the SUBSCRIBE procedure used by the UE to subscribe for a "registration-state event package." To subscribe for this package, the UE sends a SUBSCRIBE request to the network and in response it receives a NOTIFY request which may include a timer value indicating a duration within which the UE is to refresh the subscription to the registration-state event package.

[0021] Access control refers to congestion control methods for preventing UE access to a network for certain types of traffic. Access control can be implemented in two different ways, e.g., by the UE and / or by the network. An access check can be performed at the UE prior to requesting access for a service. In this process, the UE determines whether a connection for a mobile originating (MO) service is barred based on broadcast information received from a gNB in a master information block (MIB) and / or a system information block (SIB) , e.g., SIB1. The broadcast information may include accessbarring information. Access control may also be implemented at the base station, where the base station determines whether a connection request sent from the UE should be served or rejected with an RRCConnectionRe ect message including a cause code. One or both methods may be used by a mobile operator. The network may bar access to various types of traffic according to traffic conditions .

[0022] Unified Access Control (UAC) refers to a mechanism for access control in which a UE associates itself with one or more Access Identities, based upon the UE SIM configuration and parameters received in information broadcast by the 5G network in SIB1 or received from the 5G network via non-access stratum (NAS) signaling, indicating the validity of the various Access Identities for the UE . When the non-access stratum (NAS) detects an access event, the NAS maps the type of request to one or more access identities and one access category, and lower layers perform access barring checks for that request based on the determined access identities and access category in view of the barring control information received in SIB1.

[0023] A UE may be assigned an access class of 0-15. Access classes 11-15 are assigned to high priority users, where classes 11, 15 are valid in the HPLMN and EHPLMN only and classes 12-14 are valid in the HPLMN, EHPLMN and VPLMNs of the home country. Most UE SIMs are provisioned with an access class within 0-9. When access control is implemented by the UE, the UE can derive an Access Identity from Access Class by reading the parameters EFACC and EFUAC_AIC from the SIM. The EFACC parameter contains the access class of the UE . The EFUAC AIC contains information regarding whether Multimedia Priority Service (MPS) and Mission Critical Service (MCS) Identity is to be used. The UE can alsobe assigned to use priority access identities if the network indicates the MPS Indicator (MPSI) or MCS Indicator (MCSI) in the 5GS Network feature support information element (IE) in the NAS REGISTRATION ACCEPT message.

[0024] The access identities 11-15 are mapped directly from access classes 11-15. Access identity 1 is for multimedia priority service (MPS) and access identity 2 is for mission critical service (MCS) . Access classes 0-9 are mapped to Access identity 0. Based on the requested type of access or service, each access attempt or service is assigned to an access category .

[0025] For a "normal" subscriber the access check for IMS registration involves drawing a random number 'rand' uniformly distributed in the range 0 < 'rand' < 1 and checking whether 'rand' is lower than a "barring factor" broadcast by the network. For prioritized subscribers, the check can involve checking whether a certain bit is set in a bitmap broadcast by the network.

[0026] Fig. 1 shows a diagram 100 for access control according to various exemplary embodiments. The type of access attempt or service 104 determines an access category 106 for the UE . An access check 108 is performed by the UE for the access identity 102 in combination with the access category 106 in view of the barring control information broadcast in SIB1. If the access check 108 is successful, or if the access check is requested to be skipped, the UE transmits an access request 110 including a Radio Resource Control (RRC) establishment cause.

[0027] Fig. 2a shows a table 200 for mapping an access identity and access category to an RRC establishment cause according to existing specification. The table 200 is found in TS 24.501 Table 4.5.6.1. As shown, the access category 4, for mobile originating (MO) MMTel voice, is mapped to RRC establishment cause mo-VoiceCall . The access category 5, for MO MMTel video, is mapped to RRC establishment cause mo-VideoCall . The access category 6, for MO SMS and SMSoIP, is mapped to RRC establishment cause mo-SMS. The access category 9, for MO IMS registration related signaling, is mapped to RRC establishment cause mo-Data.

[0028] A new access category for the IMS registration service was added in Rel-16 for differentiating IMS SIP registration data traffic from normal packet switched (PS) data traffic.

[0029] Fig. 2b shows a table 202 for mapping an access attempt to an access category according to existing specification. The table 202 is found in TS 24.501 Table 4.5.2.2. As shown, according to rule 7.1, an access attempt of type "mobile originating IMS registration related signaling" is mapped to the access category 9. The new access category was added so that the network has better control of UE-initiated traffic. For example, the network can allow registration- related traffic at certain times and can allow PS data traffic at other times. This was not possible in LTE and Rel-15 5G networks as the networks could not restrict PS data services without affecting the IMS registration signaling of the UE .

[0030] However, introducing an access category for IMS registration has resulted in some cases where the UE may not be able to perform IMS registration when an MMTEL session or SMSoIPis active. For example, the access category 9 can be barred even when the access categories 4, 5 and / or 6 are not barred.

[0031] As described above, 3GPP IMS specifications define IMS network handling where it will release ongoing MMTEL or SMSoIP sessions if the UE does not perform IMS registration before the registration validity timer expires. This can result in the user experiencing abrupt termination of a voice / video call or SMS transaction. Depending on the context of the MMTEL session or SMS transaction any such abrupt release will result in a problem for the user and is not expected. Present handling in 3GPP 5G specifications for the following scenario can lead to abrupt clearing of MMTEL sessions (voice / video) if the UE does not perform IMS Re-Registration for subscription refresh in time .

[0032] Fig. 3 shows a signaling diagram 300 of a scenario in which IMS re-registration fails during an MMTEL voice session, an MMTEL video session or a SMS over IP session due to an access check failure according to one example. The signaling diagram 300 includes a UE 302, a gNB 304, a UPF instance 306, and a S / P- CSCF instance 308. When the IMS re-registration fails during the ongoing session, the session can be abruptly released by the S / P-CSCF 308. In this example, the ongoing session is an MMTel voice session, however, it should be understood that the signaling diagram 300 similarly applies to MMTel video and SMSoIP.

[0033] In 310, an IMS PDU session is activated. In 315, the UE is registered for IMS and receives the registration validity timer value. In 320, the UE starts the timer with the timer value .

[0034] In 325, an MMTEL voice session is ongoing between the UE and the network. In 330, the UE determines that it needs to initiate an IMS re-registration before the registration validity timer expires. The UE attempts to re-register before the timer expires and performs access barring checks as per TS 24.501 section 4.5.1.

[0035] In 335, in this example, the access check for IMS registration fails, e.g. , if a random number 'rand' drawn by the UE uniformly from the interval 0 < 'rand' < 1 is greater or equal than a barring factor broadcast by the network for the access category 9 for IMS registration. The UE waits for expiry of the barring time broadcast by the network for IMS registration signaling service, however, before this occurs, the IMS network initiates de-registration of UE for IMS services. In 340, the S / P-CSCF does not receive the re-registration attempt from the UE before the timer expires. In 345, the S / P-CSCF initiates the release of the ongoing MMTEL session.

[0036] According to one aspect of the present disclosure, the UE is allowed to skip the access check for IMS registration when an MMTel session or SMSoIP is ongoing. Thus, even if access for IMS registration is barred by the network in SIB1, the UE can transmit the registration request while the service is ongoing and prior to the expiration of the timer. Appropriate specification changes may be made to TS 3GPP 24.501 so that the UE performs the access check only when the 5G mobility management (5GMM) receives an MO-IMS-registration-related- signaling-started indication and no MMTEL voice call, MMTEL video call or SMSoIP is ongoing. The UE does not perform theaccess check when the 5G mobility management (5GMM) receives an MO-IMS-registration-related-signaling-started indication and an MMTEL voice call, MMTEL video call or SMSoIP is ongoing.

[0037] Fig. 4 shows a signaling diagram 400 for IMS reregistration including skipping an access check during an MMTEL voice session, an MMTEL video session or a SMS over IP session according to various exemplary embodiments. Similar to the signaling diagram 300 of Fig. 3, the signaling diagram 400 includes a UE 402, a gNB 404, a UPF instance 406, and a S / P-CSCF instance 408. Operations 410-430 correspond to operations 310- 330 of the signaling diagram 300 and further description of these operations is omitted hereinafter.

[0038] In 435, in this example, the UE skips the access check for IMS registration. In 440, the UE transmits the registration request and re-registers with the IMS. In 445, the MMTel session continues.

[0039] An example of a change to TS 3GPP 24.501 to implement the above described aspect may be as follows:The UE shall perform access barring checks if it is in 5GMM- CONNECTED mode over 3GPP access and one of the following events occurs :1) 5GMM receives an MO-MMTEL-voice-call-started indication, an MO-MMTEL-video-call-started indication or an MO-SMSoIP- attempt-started indication from upper layers; la) 5GMM receives an MO-IMS-registration-related-signaling- started indication and no MMTEL voice call, MMTEL video call or SMSoIP is ongoing;2) 5GMM receives a request from upper layers to send a mobile originated SMS over NAS unless the request triggered aservice request procedure to transition the UE from 5GMM-IDLE mode or 5GMM-IDLE mode with suspend indication to 5GMM-C0NNECTED mode ;3) 5GMM receives a request from upper layers to send an UL NAS TRANSPORT message for the purpose of PDU session establishment unless the request triggered a service request procedure to transition the UE from 5GMM-IDLE mode or 5GMM-IDLE mode with suspend indication to 5 GMM- CONNECTED mode;4) 5GMM receives a request from upper layers to send an UL NAS TRANSPORT message for the purpose of PDU session modification unless the request triggered a service request procedure to transition the UE from 5GMM-IDLE mode or 5GMM-IDLE mode with suspend indication to 5 GMM- CONNECTED mode;5) 5GMM receives a request to re-establish the user-plane resources for an existing PDU session;6) 5GMM is notified that an uplink user data packet is to be sent for a PDU session with suspended user-plane resources.

[0040] In another embodiment, the UE is allowed to skip the access check for the SUBSCRIBE procedure when an MMTel session or SMSoIP is ongoing. As discussed above, this procedure includes the UE sending a SUBSCRIBE request to the network. The subscription and subscription refresh procedure is also mapped to "MO IMS registration related signaling" according to rule 7.1 discussed above in Fig. 2b. When the UE determines that it needs to initiate a signaling procedure for a subscription refresh, and at least one of an MMTel voice / video session or SMSoIP is ongoing, the UE can skip the access barring checks and send the SUBSCRIBE request right away.

[0041] According to another aspect of the present disclosure, the P / S-CSCF can delay the release of the MMTel session orSMSoIP session for a UE when the sessions are ongoing and the UE has not performed re-registration. Thus, the ongoing session can continue until its natural termination prior to deregistering the UE . It is also possible the UE is able to reregister after the expiry of the registration validity timer but before the termination of the session. Appropriate specification changes may be made to TS 24.229 and / or TS 23.288 so that the IMS does not release the MMTel / IMSoIP session or clear the network states for the UE while the MMTel / IMSoIP session is ongoing.

[0042] It is noted that this second embodiment would involve greater changes to 3GPP specification than the first embodiment in which the UE skips the access check.

[0043] Fig. 5 shows an exemplary network arrangement 500 according to various exemplary embodiments. The exemplary network arrangement 500 include UEs 510, 512. Those skilled in the art will understand that the UEs 510, 512 may be any type of electronic component that is configured to communicate via a network, e.g., mobile phones, tablet computers, desktop computers, smartphones, phablets, embedded devices, wearables (e.g., HMD, AR glasses, etc.) , Internet of Things (loT) devices, etc. It should also be understood that an actual network arrangement may include any number of UEs being used by any number of users. Thus, the example of two UEs 510, 512 is merely provided for illustrative purposes.

[0044] The UEs 510, 512 may communicate directly with one or more networks. In the example of the network configuration 500, the networks with which the UEs 510, 512 may wirelessly communicate are a 5G NR radio access network (5G NR-RAN) 520, anLTE radio access network (LTE-RAN) 522 and a wireless local access network (WLAN) 524. However, the UEs 510, 512 may also communicate with other types of networks and the UEs 510, 512 may also communicate with networks over a wired connection. Therefore, the UEs 510, 512 may include a 5G NR chipset to communicate with the 5G NR-RAN 520, an LTE chipset to communicate with the LTE-RAN 522 and an ISM chipset to communicate with the WLAN 524.

[0045] The 5G NR-RAN 520 and the LTE-RAN 522 may be portions of cellular networks that may be deployed by a network carrier (e.g., Verizon, AT&T, T-Mobile, etc.) . These networks 520, 522 may include, for example, cells or base stations (Node Bs, eNodeBs, HeNBs, eNBS, gNBs, gNodeBs, macrocells, microcells, small cells, femtocells, etc.) that are configured to send and receive traffic from UEs that are equipped with the appropriate cellular chip set. The WLAN 524 may include any type of wireless local area network (WiFi, Hot Spot, IEEE 802. llx networks, etc . ) .

[0046] The UEs 510, 512 may connect to the 5G NR-RAN via the gNB 520A or the gNB 520B. Reference to two gNBs 520A, 520B is merely for illustrative purposes. The exemplary embodiments may apply to any appropriate number of gNBs. The UEs 510, 512 may also connect to the LTE-RAN 522 via the eNBs 522A, 522B. Those skilled in the art will understand that any association procedure may be performed for the UEs 510, 512 to connect to the 5G NR-RAN 520 and the LTE-RAN 522. For example, as discussed above, the 5G NR-RAN 520 and the LTE-RAN 522 may be associated with a particular cellular provider where the UEs 510, 512 and / or the user thereof has a contract and credential information (e.g., stored on a SIM card) . Upon detecting thepresence of the 5G NR-RAN 520, the UEs 510, 512 may transmit the corresponding credential information to associate with the 5G NR-RAN 520. More specifically, the UEs 510, 512 may associate with a specific base station (e.g., the gNB 520A of the 5G NR- RAN 520, the eNB 522A of the LTE-RAN 522) .

[0047] In addition to the networks 520, 522 and 524 the network arrangement 500 also includes a cellular core network 530, the Internet 540, an IP Multimedia Subsystem (IMS) 550, and a network services backbone 560. The cellular core network 530 may be considered to be the interconnected set of components that manages the operation and traffic of the cellular network. The cellular core network 530 also manages the traffic that flows between the cellular network and the Internet 540. The IMS 550 may be generally described as an architecture for delivering multimedia services to the UEs 510, 512 using the IP protocol. The IMS 550 may communicate with the cellular core network 530 and the Internet 540 to provide the multimedia services to the UEs 510, 512. The network services backbone 560 is in communication either directly or indirectly with the Internet 540 and the cellular core network 530. The network services backbone 560 may be generally described as a set of components (e.g., servers, network storage arrangements, etc.) that implement a suite of services that may be used to extend the functionalities of the UEs 510, 512 in communication with the various networks .

[0048] Fig. 6 shows an exemplary UE 510 according to various exemplary embodiments. The UE 510 will be described with regard to the network arrangement 500 of Fig. 5. The UE 510 may include a processor 605, a memory arrangement 610, a display device 615, an input / output (I / O) device 620, a transceiver 625and other components 630 . The other components 630 may include , for example , an audio input device , an audio output device , a power supply, a data acquisition device, ports to electrically connect the UE 510 to other electronic devices , etc .

[0049] The processor 605 may be configured to execute a plurality of engines of the UE 510 . For example , the engines may include an access check engine 635 for performing various operations related to skipping an access check for IMS registration when a MMTel or SMSoIP session is ongoing, as described above .

[0050] The above referenced engine 635 being an application ( e . g . , a program) executed by the processor 605 is provided merely for illustrative purposes . The functionality associated with the engine 635 may also be represented as a separate incorporated component of the UE 510 or may be a modular component coupled to the UE 510 , e . g . , an integrated circuit with or without firmware . For example, the integrated circuit may include input circuitry to receive signals and processing circuitry to process the signals and other information . The engines may also be embodied as one application or separate applications . In addition, in some UEs , the functionality described for the processor 605 is split among two or more processors such as a baseband processor and an applications processor . The exemplary embodiments may be implemented in any of these or other configurations of a UE .

[0051] The memory arrangement 610 may be a hardware component configured to store data related to operations performed by the UE 510 . The display device 615 may be a hardware component configured to show data to a user while the I / O device 620 maybe a hardware component that enables the user to enter inputs.The display device 615 and the I / O device 620 may be separate components or integrated together such as a touchscreen. The transceiver 625 may be a hardware component configured to establish a connection with the 5G NR-RAN 520 and / or any other appropriate type of network. Accordingly, the transceiver 625 may operate on a variety of different frequencies or channels (e.g., set of consecutive frequencies) . The transceiver 625 includes circuitry configured to transmit and / or receive signals (e.g., control signals, data signals) . Such signals may be encoded with information implementing any one of the methods described herein. The processor 605 may be operably coupled to the transceiver 625 and configured to receive from and / or transmit signals to the transceiver 625. The processor 605 may be configured to encode and / or decode signals (e.g., signaling from a base station of a network) for implementing any one of the methods described herein.Examples

[0052] In a first example, a method comprising decoding an internet protocol (IP) multimedia subsystem (IMS) registration response including a timer value for IMS registration validity, starting a timer with the timer value, prior to the timer expiring, initiating a registration with the IMS, when at least one service of a group of services is ongoing over IMS, skipping an access check for IMS registration and configuring transceiver circuitry to transmit an IMS registration request without performing the access check for IMS registration.

[0053] In a second example, the method of the first example, wherein the group of services comprises a multimedia telephony (MMTel) voice session or MMTel video session.

[0054] In a third example, the method of the first example, wherein the group of services comprises a short messaging service (SMS) over IP session.

[0055] In a fourth example, a processor of a user equipment configured to perform any of the methods of the first through third examples.

[0056] In a fifth example, user equipment comprising a transceiver configured to communicate with a network and a processor communicatively coupled to the transceiver and configured to perform any of the methods of the first through third examples.

[0057] In a sixth example, a method comprising decoding an internet protocol (IP) multimedia subsystem (IMS) NOTIFY request including a timer value for subscription validity, starting a timer with the timer value, prior to the timer expiring, initiating a subscription refresh, when at least one service of a group of services is ongoing over IMS, skipping an access check for transmitting a SUBSCRIBE request and configuring transceiver circuitry to transmit the SUBSCRIBE request without performing the access check for the SUBSCRIBE request.

[0058] In a seventh example, the method of the sixth example, wherein the group of services comprises a multimedia telephony (MMTel) voice session or MMTel video session.

[0059] In an eighth example, the method of the sixth example, wherein the group of services comprises a short messaging service (SMS) over IP session.

[0060] In a ninth example, a processor of a user equipment configured to perform any of the methods of the sixth through eighth examples.

[0061] In a tenth example, user equipment comprising a transceiver configured to communicate with a network and a processor communicatively coupled to the transceiver and configured to perform any of the methods of the sixth through eighth examples.

[0062] In an eleventh example, a method comprising transmitting an internet protocol (IP) multimedia subsystem (IMS) registration response to a user equipment (UE) including a timer value for IMS registration validity, starting a timer with the timer value, when the timer expires while the UE has at least one service of a group of services ongoing over IMS, delaying a deregistration of the UE until the service is inactive .

[0063] In a twelfth example, the method of the eleventh example, wherein the group of services comprises a multimedia telephony (MMTel) voice session or MMTel video session.

[0064] In a thirteenth example, the method of the eleventh example, wherein the group of services comprises a short messaging service (SMS) over IP session.

[0065] In a fourteenth example, a processor of a network server configured to perform any of the methods of the eleventh through thirteenth examples.

[0066] In a fi fteenth example, a network server configured to perform any of the methods of the eleventh through thirteenth examples .

[0067] Those skilled in the art will understand that the above-described exemplary embodiments may be implemented in any suitable software or hardware configuration or combination thereof . An exemplary hardware platform for implementing the exemplary embodiments may include, for example , an Intel x86 based platform with compatible operating system, a Windows OS , a Mac platform and MAC OS , a mobile device having an operating system such as iOS , Android, etc . The exemplary embodiments described above may be embodied as a program containing lines of code stored on a non-transitory computer readable storage medium that, when compiled, may be executed on a processor or microprocessor .

[0068] Although this application described various embodiments each having different features in various combinations , those skilled in the art will understand that any of the features of one embodiment may be combined with the features of the other embodiments in any manner not speci fically disclaimed or which is not functionally or logically inconsistent with the operation of the device or the stated functions of the disclosed embodiments .

[0069] It is well understood that the use of personally identi fiable information should follow privacy policies and practices that are generally recogni zed as meeting or exceeding industry or governmental requirements for maintaining the privacy of users . In particular, personally identifiable information data should be managed and handled so as to minimi zerisks of unintentional or unauthori zed access or use , and the nature of authori zed use should be clearly indicated to users .

[0070] It will be apparent to those skilled in the art that various modi fications may be made in the present disclosure , without departing from the spirit or the scope of the disclosure . Thus , it is intended that the present disclosure cover modifications and variations of this disclosure provided they come within the scope of the appended claims and their equivalent .

Claims

What is Claimed:

1. An apparatus of a user equipment (UE) , the apparatus comprising processing circuitry configured to: decode an internet protocol (IP) multimedia subsystem (IMS) registration response including a timer value for IMS registration validity; start a timer with the timer value; prior to the timer expiring, initiate a registration with the IMS; when at least one service of a group of services is ongoing over IMS, skip an access check for IMS registration; and configure transceiver circuitry to transmit an IMS registration request without performing the access check for IMS registration .

2. The apparatus of claim 1, wherein the group of services comprises a multimedia telephony (MMTel) voice session or MMTel video session.

3. The apparatus of claim 1, wherein the group of services comprises a short messaging service (SMS) over IP session.

4. An apparatus of a user equipment (UE) , the apparatus comprising processing circuitry configured to: decode an internet protocol (IP) multimedia subsystem (IMS) NOTIFY request including a timer value for subscription validity; start a timer with the timer value; prior to the timer expiring, initiate a subscription refresh;when at least one service of a group of services is ongoing over IMS, skip an access check for transmitting a SUBSCRIBE request; and configure transceiver circuitry to transmit the SUBSCRIBE request without performing the access check for the SUBSCRIBE request .

5. The apparatus of claim 4, wherein the group of services comprises a multimedia telephony (MMTel) voice session or MMTel video session.

6. The apparatus of claim 4, wherein the group of services comprises a short messaging service (SMS) over IP session.

7. A method performed by an internet protocol (IP) multimedia subsystem (IMS) entity, comprising: transmitting an IMS registration response to a user equipment (UE) including a timer value for IMS registration validity; starting a timer with the timer value; when the timer expires while the UE has at least one service of a group of services ongoing over IMS, delaying a deregistration of the UE until the service is inactive.

8. The method of claim 7, wherein the group of services comprises a multimedia telephony (MMTel) voice session or MMTel video session.

9. The method of claim 7, wherein the group of services comprises a short messaging service (SMS) over IP session.

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