On Inter-System Registration Failure Case In Mobile Communications

Examples pertaining to an improvement on the inter-system registration failure case in mobile communications are described. A user equipment (UE) performs a registration procedure with a wireless network after an inter-system change. In response to detecting a failure of the registration procedure, the UE reattempts the registration procedure. The UE reattempts the registration procedure either: (i) after detecting the failure; or (ii) upon expiry of a first timer used by the UE which has a shorter duration than a second timer used by the UE.

TECHNICAL FIELD

The present disclosure is generally related to mobile communications and, more particularly, to an improvement on the inter-system registration failure case in mobile communications.

BACKGROUND

In wireless communications, including mobile communications in accordance with the 3rdGeneration Partnership Project (3GPP) specification(s) such as the 3GPP Technical Specification (TS) 23.502 and TS 23.401, after an inter-system change from an Evolved Packet System (EPS) to a 5thGeneration System (5GS) by a user equipment (UE) in an idle mode, the 5thGeneration Mobility Management (5GMM) layer is to include an integrity protected TRACKING AREA UPDATE (TAU) REQUEST message in a 5GMM REGISTRATION REQUEST message. The source Mobility Management Entity (MME) in the EPS integrity verifies the TRACKING AREA UPDATE REQUEST during the registration procedure and sends a failure indication to the target Access and Mobility Management Function (AMF) if the verification fails, thereby causing a 5GMM REGISTRATION REJECT message being sent to the UE. If the integrity verification in the MME is successful, the Mobility Management (MM) context is to be transferred to the target AMF and be removed from the source MME. The source MME may keep the MM context for an implementation-specific time after MM context transfer in order to allow the UE to reattempt the procedure in case of a failure. A reattempt may be necessary, for example, if the EPS tracking area updating or 5GMM registration procedure fails abnormally. The context preservation may be controlled by an implementation-specific timer.

If the 5GMM registration procedure fails abnormally, the UE is to reattempt registration after the expiry of timer T3511 (e.g., 10 seconds). However, if the MM context preservation timer in the MME is shorter than timer T3511, the MM context would be removed from the source MME before the new registration attempt. This would result in a failure when the MME is unable to verify the TRACKING AREA UPDATE REQUEST and thus would lead to a 5GMM registration failure. Therefore, there is a need for a solution of an improvement on the inter-system registration failure case in mobile communications.

SUMMARY

One objective of the present disclosure is propose schemes, concepts, designs, systems, methods and apparatus pertaining to an improvement on the inter-system registration failure case in mobile communications. It is believed that the above-described issue would be avoided or otherwise alleviated by implementing one or more of the proposed schemes described herein.

In one aspect, a method may involve a processor of an apparatus (e.g., UE) performing a registration procedure with a wireless network after an inter-system change. The method may also involve the processor detecting a failure of the registration procedure. In response to the detecting, the method may further involve the processor reattempting the registration procedure either: (i) after detecting the failure; or (ii) upon expiry of a first timer used by the UE which has a shorter duration than a second timer used by the UE.

In another aspect, an apparatus may include a transceiver and a processor coupled to the transceiver. The transceiver may be configured to communicate with a wireless network. The processor may perform, via the transceiver, a registration procedure with a wireless network after an inter-system change. The processor may also detect, via the transceiver, a failure of the registration procedure. In response to the detecting, the processor may reattempt, via the transceiver, the registration procedure either: (i) after detecting the failure; or (ii) upon expiry of a first timer used by the UE which has a shorter duration than a second timer used by the UE.

It is noteworthy that, although description provided herein may be in the context of certain radio access technologies, networks and network topologies such as 5G/New Radio (NR) and 4thGeneration (4G) EPS mobile networking, the proposed concepts, schemes and any variation(s)/derivative(s) thereof may be implemented in, for and by other types of wireless and wired communication technologies, networks and network topologies such as, for example and without limitation, Ethernet, Universal Terrestrial Radio Access Network (UTRAN), Evolved UTRAN (E-UTRAN), Global System for Mobile communications (GSM), General Packet Radio Service (GPRS)/Enhanced Data rates for Global Evolution (EDGE) Radio Access Network (GERAN), Long-Term Evolution (LTE), LTE-Advanced, LTE-Advanced Pro, Internet-of-Things (IoT), Industrial loT (IIoT), Narrow Band Internet of Things (NB-loT), and any future-developed networking technologies. Thus, the scope of the present disclosure is not limited to the examples described herein.

DETAILED DESCRIPTION OF PREFERRED IMPLEMENTATIONS

Overview

FIG.1illustrates an example network environment100in which various solutions and schemes in accordance with the present disclosure may be implemented.FIG.2~FIG.5illustrate examples of implementation of various proposed schemes in network environment100in accordance with the present disclosure. The following description of various proposed schemes is provided with reference toFIG.1~FIG.5.

Referring toFIG.1, network environment100may involve a UE110and a wireless network120, which may include a 5GS and an EPS. Depending on channel condition, availability and/or other factor(s), UE110may be in wireless communication with wireless network120via one or more network nodes as represented by a network node125. Wireless network120may also include an AMF and an MME (e.g., as part of 5GS although they are shown separate from the 5GS inFIG.1). In network environment100, UE110and wireless network120may implement various schemes pertaining to an improvement on the inter-system registration failure case in mobile communications in accordance with the present disclosure, as described below. It is noteworthy that, while the various proposed schemes may be individually or separately described below, in actual implementations each of the proposed schemes may be utilized individually or separately. Alternatively, some or all of the proposed schemes may be utilized jointly.

Under a proposed scheme in accordance with the present disclosure, in an event that a 5GMM registration procedure for inter-system change (e.g., from EPS to 5GS) when UE110is in an idle mode, UE110may have an option to reattempt registration earlier than expiry of timer T3511 before the MM context is removed from the source MME. That is, under the proposed scheme, the MME would still have the MM context when the registration is reattempted by UE110so that the TRACKING AREA UPDATE REQUEST integrity verification and the 5GMM registration may be successful. Under the proposed scheme, this may be achieved in one or more ways. For instance, in a first approach, UE110may use a timer which is started after detecting the 5GMM abnormal registration failure. In some implementations, the timer may be T3511 timer with a shorter duration. In other implementations, the timer may be a new timer which is of a shorter duration than that of T3511, and this new timer may be used to trigger a new (reattempted) registration procedure.

In a second approach under the proposed scheme, UE110may restart the registration procedure immediately after detecting the 5GMM abnormal registration failure. That is, UE110may restart the registration procedure without any delay upon detection of the 5GMM abnormal registration failure. In a third approach under the proposed scheme, UE110may restart the registration procedure immediately upon release of an NR radio resource control (NRRC) connection after detecting the 5GMM abnormal registration failure. In a fourth approach under the proposed scheme, UE110may use a timer, which is started upon release of the NRRC connection after detecting the 5GMM abnormal registration failure, to trigger a new registration procedure.

It is noteworthy that the term “failure” or “abnormal failure” herein may refer to an abnormal failure that occurs despite wireless network120successfully validates the TRACKING AREA UPDATE REQUEST from UE110. Moreover, the term “failure” or “abnormal failure” herein may also refer to an abnormal failure that occurs before UE110receives a REGISTRATION ACCEPT message from wireless network120.

For illustrative purposes only and without limiting the scope of the present disclosure,FIG.2illustrates an example scenario200in which various solutions and schemes in accordance with the present disclosure may be implemented. In scenario200, initially, a UE (e.g., UE110) may be registered in a 4G EPS and UE110may then change its connection from the 4G EPS to a 5GS. That is, UE110may be registered and in an idle mode when connected to the 4G EPS and then chooses to move to a 5GS cell in the idle mode. Then, the UE may initiate a registration procedure by transmitting a REGISTRATION REQUEST message (including a TRACKING AREA UPDATE REQUEST) to an AMF of the wireless network (e.g., via network node125). The AMF may, in turn, forward a context request (including the TRACKING AREA UPDATE REQUEST) to an MME of the wireless network. The MME may validate the TRACKING AREA UPDATE REQUEST successfully and, in response, send a context response (with an MM context) to the AMF. The MME may delete the MM context either immediately or upon expiry of a timer Tx(which may be started by the MME upon successful validation of the TRACKING AREA UPDATE REQUEST). On the other hand, an abnormal failure in the registration procedure may occur before the UE receives a REGISTRATION ACCEPT message from the AMF. Upon determining that there is an abnormal failure in the registration procedure, the UE may start a timer T3511 upon the expiry of which the UE may reattempt the registration procedure by transmitting another REGISTRATION REQUEST message (including a TRACKING AREA UPDATE REQUEST) to the AMF. The AMF may, in turn, forward a context request (including the TRACKING AREA UPDATE REQUEST) to the MME. However, in scenario200, as no UE information is available (since the MM context associated with the UE had been deleted), validation of the TRACKING AREA UPDATE REQUEST by the MME may result in failure. Thus, the MME sends a context response, with an indication of validation failure, to the AMF, which in turn sends a REGISTRATION REJECT message to the UE.

For illustrative purposes only and without limiting the scope of the present disclosure,FIG.3illustrates an example scenario300in which various solutions and schemes in accordance with the present disclosure may be implemented. In scenario300, initially, a UE (e.g., UE110) may be registered in a 4G EPS and UE110may then change its connection from the 4G EPS to a 5GS. That is, UE110may be registered and in an idle mode when connected to the 4G EPS and then chooses to move to a 5GS cell while in the idle mode. Then, the UE may initiate a registration procedure by transmitting a REGISTRATION REQUEST message (including a TRACKING AREA UPDATE REQUEST) to an AMF of the wireless network (e.g., via network node125). The AMF may, in turn, forward a context request (including the TRACKING AREA UPDATE REQUEST) to an MME of the wireless network. The MME may validate the TRACKING AREA UPDATE REQUEST successfully and, in response, send a context response (with an MM context) to the AMF. The MME may delete the MM context either immediately or upon expiry of a timer Tx(which may be started by the MME upon successful validation of the TRACKING AREA UPDATE REQUEST). On the other hand, an abnormal failure in the registration procedure may occur before the UE receives a REGISTRATION ACCEPT message from the AMF. Upon determining that there is an abnormal failure in the registration procedure, the UE may reattempt the registration procedure either: (i) immediately (e.g., without delay) upon determining or detecting the abnormal failure, or (ii) upon expiry of a timer Tywhich has a duration shorter than that of timer Tx. That is, the UE may reattempt the registration procedure by transmitting another REGISTRATION REQUEST message (including a TRACKING AREA UPDATE REQUEST) to the AMF. The AMF may, in turn, forward a context request (including the TRACKING AREA UPDATE REQUEST) to the MME. In scenario300, as the UE reattempts the registration procedure before timer Txat the MME expires, validation of the TRACKING AREA UPDATE REQUEST by the MME results in success. Thus, the MME sends a context response, with an MM context, to the AMF, which in turn sends a REGISTRATION ACCEPT message to the UE to complete the registration procedure.

Illustrative Implementations

FIG.4illustrates an example communication system400having at least an example apparatus410and an example apparatus420in accordance with an implementation of the present disclosure. Each of apparatus410and apparatus420may perform various functions to implement schemes, techniques, processes and methods described herein pertaining to an improvement on the inter-system registration failure case in mobile communications, including the various schemes described above with respect to various proposed designs, concepts, schemes, systems and methods described above, including network environment100, as well as processes described below.

Each of apparatus410and apparatus420may be a part of an electronic apparatus, which may be a network apparatus or a UE (e.g., UE110), such as a portable or mobile apparatus, a wearable apparatus, a vehicular device or a vehicle, a wireless communication apparatus or a computing apparatus. For instance, each of apparatus410and apparatus420may be implemented in a smartphone, a smart watch, a personal digital assistant, an electronic control unit (ECU) in a vehicle, a digital camera, or a computing equipment such as a tablet computer, a laptop computer or a notebook computer. Each of apparatus410and apparatus420may also be a part of a machine type apparatus, which may be an loT apparatus such as an immobile or a stationary apparatus, a home apparatus, a roadside unit (RSU), a wire communication apparatus or a computing apparatus. For instance, each of apparatus410and apparatus420may be implemented in a smart thermostat, a smart fridge, a smart door lock, a wireless speaker or a home control center. When implemented in or as a network apparatus, apparatus410and/or apparatus420may be implemented in an eNodeB in an LTE, LTE-Advanced or LTE-Advanced Pro network or in a gNB or TRP in a 5G network, an NR network or an loT network.

In some implementations, each of apparatus410and apparatus420may be implemented in the form of one or more integrated-circuit (IC) chips such as, for example and without limitation, one or more single-core processors, one or more multi-core processors, one or more complex-instruction-set-computing (CISC) processors, or one or more reduced-instruction-set-computing (RISC) processors. In the various schemes described above, each of apparatus410and apparatus420may be implemented in or as a network apparatus or a UE. Each of apparatus410and apparatus420may include at least some of those components shown inFIG.4such as a processor412and a processor422, respectively, for example. Each of apparatus410and apparatus420may further include one or more other components not pertinent to the proposed scheme of the present disclosure (e.g., internal power supply, display device and/or user interface device), and, thus, such component(s) of apparatus410and apparatus420are neither shown inFIG.4nor described below in the interest of simplicity and brevity.

In some implementations, apparatus410may also include a transceiver416coupled to processor412. Transceiver416may be capable of wirelessly transmitting and receiving data. In some implementations, transceiver416may be capable of wirelessly communicating with different types of wireless networks of different radio access technologies (RATs). In some implementations, transceiver416may be equipped with a plurality of antenna ports (not shown) such as, for example, four antenna ports. That is, transceiver416may be equipped with multiple transmit antennas and multiple receive antennas for multiple-input multiple-output (MIMO) wireless communications. In some implementations, apparatus420may also include a transceiver426coupled to processor422. Transceiver426may include a transceiver capable of wirelessly transmitting and receiving data. In some implementations, transceiver426may be capable of wirelessly communicating with different types of UEs/wireless networks of different RATs. In some implementations, transceiver426may be equipped with a plurality of antenna ports (not shown) such as, for example, four antenna ports. That is, transceiver426may be equipped with multiple transmit antennas and multiple receive antennas for MIMO wireless communications.

In some implementations, apparatus410may further include a memory414coupled to processor412and capable of being accessed by processor412and storing data therein. In some implementations, apparatus420may further include a memory424coupled to processor422and capable of being accessed by processor422and storing data therein. Each of memory414and memory424may include a type of random-access memory (RAM) such as dynamic RAM (DRAM), static RAM (SRAM), thyristor RAM (T-RAM) and/or zero-capacitor RAM (Z-RAM). Alternatively, or additionally, each of memory414and memory424may include a type of read-only memory (ROM) such as mask ROM, programmable ROM (PROM), erasable programmable ROM (EPROM) and/or electrically erasable programmable ROM (EEPROM). Alternatively, or additionally, each of memory414and memory424may include a type of non-volatile random-access memory (NVRAM) such as flash memory, solid-state memory, ferroelectric RAM (FeRAM), magnetoresistive RAM (MRAM) and/or phase-change memory. Alternatively, or additionally, each of memory414and memory424may include a UICC.

Each of apparatus410and apparatus420may be a communication entity capable of communicating with each other using various proposed schemes in accordance with the present disclosure. For illustrative purposes and without limitation, a description of capabilities of apparatus410, as a UE (e.g., UE110), and apparatus420, as a network node (e.g., network node125) of a wireless network (e.g., wireless network120), is provided below.

Under various proposed schemes in accordance with the present disclosure with respect to an improvement on the inter-system registration failure case in mobile communications, processor412of apparatus410, implemented in or as UE110, may, when in an idle mode, perform, via transceiver416, a registration procedure with a wireless network (e.g., wireless network120via apparatus420as network node125) after an inter-system change (e.g., between 5GS and EPS). Additionally, processor412may detect, via transceiver416, a failure of the registration procedure. Moreover, in response to the detecting, processor412may reattempt, via transceiver416, the registration procedure either: (i) after detecting the failure; or (ii) upon expiry of a first timer used by the UE which has a shorter duration than a second timer used by the UE.

In some implementations, in reattempting the registration procedure, processor412may restart the registration procedure without delay after detecting the failure.

In some implementations, in reattempting the registration procedure, processor412may restart the registration procedure without delay upon release of an NRRC connection after detecting the failure.

In some implementations, in reattempting the registration procedure, processor412may perform certain operations. For instance, processor412may set a shorter duration for a T3511 timer, as the first timer, to be shorter than a duration of a normal T3511 timer, as the second timer. Moreover, processor412may transmit a registration request to the wireless network upon expiry of the T3511 timer with the shorter duration.

Alternatively, or additionally, in reattempting the registration procedure, processor412may perform certain operations. For instance, processor412may start a new timer, as the first timer, having a duration shorter than that of a T3511 timer, as the second timer. Additionally, processor412may transmit a registration request to the wireless network upon expiry of the new timer.

Alternatively, or additionally, in reattempting the registration procedure, processor412may perform certain other operations. For instance, processor412may start a new timer, as the first timer, upon release of an NRRC connection after detecting the failure, the new timer having a duration shorter than that of a T3511 timer, as the second timer. Furthermore, processor412may transmit a registration request to the wireless network upon expiry of the new timer.

In some implementations, in performing the registration procedure with the wireless network after the inter-system change, processor412may perform a 5GMM registration procedure when in the idle mode after changing from an EPS to a 5GS.

In some implementations, in performing the registration procedure with the wireless network, processor412may transmit a registration request with an integrity-protected TAU request to the wireless network.

In some implementations, the failure may include an abnormal failure that occurs despite the wireless network validates the TAU request successfully. In some implementations, the failure may include an abnormal failure that occurs before receiving a registration accept message from the wireless network.

Illustrative Processes

FIG.5illustrates an example process500in accordance with an implementation of the present disclosure. Process500may represent an aspect of implementing various proposed designs, concepts, schemes, systems and methods described above, whether partially or entirely, including those described above. More specifically, process500may represent an aspect of the proposed concepts and schemes pertaining to an improvement on the inter-system registration failure case in mobile communications. Process500may include one or more operations, actions, or functions as illustrated by one or more of blocks510,520and530. Although illustrated as discrete blocks, various blocks of process500may be divided into additional blocks, combined into fewer blocks, or eliminated, depending on the desired implementation. Moreover, the blocks/sub-blocks of process500may be executed in the order shown inFIG.5or, alternatively in a different order. Furthermore, one or more of the blocks/sub-blocks of process500may be executed iteratively. Process500may be implemented by or in apparatus410and apparatus420as well as any variations thereof. Solely for illustrative purposes and without limiting the scope, process500is described below in the context of apparatus410as a UE (e.g., UE110) and apparatus420as a communication entity such as a network node or base station (e.g., network node125) of a wireless network (e.g., wireless network120). Process500may begin at block510.

At510, process500may involve processor412of apparatus410, implemented in or as UE110, performing, when in an idle mode and via transceiver416, a registration procedure with a wireless network (e.g., wireless network120via apparatus420as network node125) after an inter-system change (e.g., between 5GS and EPS). Process500may proceed from510to520.

At520, process500may involve processor412detecting, via transceiver416, a failure of the registration procedure. Process500may proceed from520to530.

At530, in response to the detecting, process500may involve processor412reattempting, via transceiver416, the registration procedure either: (i) after detecting the failure; or (ii) upon expiry of a first timer used by the UE which has a shorter duration than a second timer used by the UE.

In some implementations, in reattempting the registration procedure, process500may involve processor412restarting the registration procedure without delay after detecting the failure.

In some implementations, in reattempting the registration procedure, process500may involve processor412restarting the registration procedure without delay upon release of an NRRC connection after detecting the failure.

In some implementations, in reattempting the registration procedure, process500may involve processor412performing certain operations. For instance, process500may involve processor412setting a shorter duration for a T3511 timer, as the first timer, to be shorter than a duration of a normal T3511 timer, as the second timer. Moreover, process500may involve processor412transmitting a registration request to the wireless network upon expiry of the T3511 timer with the shorter duration.

Alternatively, or additionally, in reattempting the registration procedure, process500may involve processor412performing certain operations. For instance, process500may involve processor412starting a new timer, as the first timer, having a duration shorter than that of a T3511 timer, as the second timer. Additionally, process500may involve processor412transmitting a registration request to the wireless network upon expiry of the new timer.

Alternatively, or additionally, in reattempting the registration procedure, process500may involve processor412performing certain operations. For instance, process500may involve processor412starting a new timer, as the first timer, upon release of an NRRC connection after detecting the failure, the new timer having a duration shorter than that of a T3511 timer, as the second timer. Furthermore, process500may involve processor412transmitting a registration request to the wireless network upon expiry of the new timer.

In some implementations, in performing the registration procedure with the wireless network after the inter-system change, process500may involve processor412performing a 5GMM registration procedure when in the idle mode after changing from an EPS to a 5GS.

In some implementations, in performing the registration procedure with the wireless network, process500may involve processor412transmitting a registration request with an integrity-protected TAU request to the wireless network.

In some implementations, the failure may include an abnormal failure that occurs despite the wireless network validates the TAU request successfully. In some implementations, the failure may include an abnormal failure that occurs before receiving a registration accept message from the wireless network.

Additional Notes