WO2022033103A1

WO2022033103A1 - Method and wireless device for selecting a radio access technology for ims registration

Info

Publication number: WO2022033103A1
Application number: PCT/CN2021/094698
Authority: WO
Inventors: Xin Xu; Jaehyeuk YANG; Yongsheng Shi
Original assignee: Guangdong Oppo Mobile Telecommunications Corp., Ltd.
Priority date: 2020-08-12
Filing date: 2021-05-19
Publication date: 2022-02-17

Abstract

A wireless device executes a method for selecting a radio access technology (RAT) for registration to an Internet protocol (IP) multimedia subsystem (IMS). The wireless device obtains a plurality of RATs rated in a first arrangement and selects a first RAT from the plurality of RATs as a selected RAT according to the first arrangement. The wireless device uses the selected RAT to perform a first attempt of IMS registration. The wireless device rates the first RAT in the plurality of RATs according to a result of the first attempt of IMS registration.

Description

METHOD AND WIRELESS DEVICE FOR SELECTING A RADIO ACCESS TECHNOLOGY FOR IMS REGISTRATION

Technical Field

The present disclosure relates to the field of communication systems, and more particularly, to a method and a wireless device for selecting a radio access technology (RAT) for registration to an Internet protocol (IP) multimedia subsystem (IMS) .

Background Art

Wireless communication systems, such as the third-generation (3G) of mobile telephone standards and technology are well known. Such 3G standards and technology have been developed by the Third Generation Partnership Project (3GPP) . The 3rd generation of wireless communications has generally been developed to support macro-cell mobile phone communications. Communication systems and networks have developed towards being a broadband and mobile system. In cellular wireless communication systems, user equipment (UE) is connected by a wireless link to a radio access network (RAN) . The RAN comprises a set of base stations (BSs) which provide wireless links to the UEs located in cells covered by the base station, and an interface to a core network (CN) which provides overall network control. As will be appreciated the RAN and CN each conduct respective functions in relation to the overall network. The 3rd Generation Partnership Project has developed the so-called Long Term Evolution (LTE) system, namely, an Evolved Universal Mobile Telecommunication System Territorial Radio Access Network, (E-UTRAN) , for a mobile access network where one or more macro-cells are supported by a base station known as an eNodeB or eNB (evolved NodeB) . More recently, LTE is evolving further towards the so-called 5G or NR (new radio) systems where one or more cells are supported by a base station known as a gNB.

Technical Problem

A UE can be stuck for a long time during IMS registration due to some issues. Among the issues of unsuccessful IMS registration, some have been observed and identified as being related to a current RAT used for the IMS registration. The issues can be persistent, and the UE even if utilizing a retry mechanism to register the IMS can still fail over the current RAT. This issue blocks voice call function, including mobile originated (MO) or mobile terminated (MT) calls, and impacts user experience significantly.

Technical Solution

An object of the present disclosure is to propose a method and a wireless device for selecting a radio access technology (RAT) for registration to an Internet protocol (IP) multimedia subsystem (IMS) .

In a first aspect, an embodiment of the invention provides a method for selecting a radio access technology (RAT) for registration to an Internet protocol (IP) multimedia subsystem (IMS) , executable in a wireless device, comprising:

obtaining a plurality of RATs rated in a first arrangement;

selecting a first RAT from the plurality of RATs as a selected RAT according to the first arrangement;

using the selected RAT to perform a first attempt of IMS registration; and

rating the first RAT in the plurality of RATs according to a result of the first attempt of IMS registration.

In a second aspect, an embodiment of the invention provides a wireless device comprising a transceiver and a processor. The processor is connected to the transceiver and configured to execute the following steps:

obtaining a plurality of RATs rated in a first arrangement;

using the selected RAT to perform a first attempt of IMS registration; and

The disclosed method may be implemented in a chip. The chip may include a processor, configured to call and run a computer program stored in a memory, to cause a device in which the chip is installed to execute the disclosed method.

The disclosed method may be programmed as computer executable instructions stored in non-transitory computer-readable medium. The non-transitory computer readable medium, when loaded to a computer, directs a processor of the computer to execute the disclosed method.

The non-transitory computer-readable medium may comprise at least one from a group consisting of: a hard disk, a CD-ROM, an optical storage device, a magnetic storage device, a read only memory, a programmable read only memory, an erasable programmable read only memory, EPROM, an electrically erasable programmable read only memory and a flash memory.

The disclosed method may be programmed as computer program product, that causes a computer to execute the disclosed method.

The disclosed method may be programmed as a computer program, that causes a computer to execute the disclosed method.

Advantageous Effects

IMS registration failure may block voice call function and impact user experience significantly. The invention isolates RAT-related IMS registration failure, ranks RATs with respect to IMS registration results, and disables a RAT that causes recurrent IMS registration failures. The invention avoids deadlocks of wasteful IMS registration retries and wasting of resources.

Description of Drawings

In order to more clearly illustrate the embodiments of the present disclosure or related art, the following figures will be described in the embodiments are briefly introduced. It is obvious that the drawings are merely some embodiments of the present disclosure, a person having ordinary skill in this field can obtain other figures according to these figures without paying the premise.

FIG. 1 illustrates a schematic view of a telecommunication system.

FIG. 2 illustrates a schematic view showing an example of IMS registration.

FIG. 3 illustrates a schematic view showing an embodiment of the method for selecting a RAT for IMS registration.

FIG. 4 illustrates a schematic view showing an embodiment of RAT deprioritizing.

FIG. 5 illustrates a schematic view showing an embodiment of RAT prioritizing.

FIG. 6 illustrates a schematic view showing an embodiment of RAT switching for IMS registration.

FIG. 7 illustrates a schematic view showing an embodiment of RAT disabling.

FIG. 8 illustrates a schematic view showing an embodiment of enabling a disabled RAT.

FIG. 9 illustrates a schematic view showing an embodiment of IMS disabling.

FIG. 10 illustrates a schematic view showing a system for wireless communication according to an embodiment of the present disclosure.

DETAILED DESCRIPTION OF EMBODIMENTS

Embodiments of the disclosure are described in detail with the technical matters, structural features, achieved objects, and effects with reference to the accompanying drawings as follows. Specifically, the terminologies in the embodiments of the present disclosure are merely for describing the purpose of the certain embodiment, but not to limit the disclosure.

With reference to FIG. 1, a telecommunication system including a UE 10a, a UE 10b, a base station (BS) 200a, and a network entity device 300 executes the disclosed method according to an embodiment of the present disclosure. FIG. 1 is shown for illustrative not limiting, and the system may comprise more UEs, BSs, and CN entities. Connections between devices and device components are shown as lines and arrows in the FIGs. The UE 10a may include a processor 11a, a memory 12a, and a transceiver 13a. The UE 10b may include a processor 11b, a memory 12b, and a transceiver 13b. The base station 200a may include a processor 201a, a memory 202a, and a transceiver 203a. The network entity device 300 may include a processor 301, a memory 302, and a transceiver 303. Each of the

processors

11a, 11b, 201a, and 301 may be configured to implement proposed functions, procedures and/or methods described in the description. Layers of radio interface protocol may be implemented in the

processors

11a, 11b, 201a, and 301. Each of the

memory

12a, 12b, 202a, and 302 operatively stores a variety of programs and information to operate a connected processor. Each of the

transceivers

13a, 13b, 203a, and 303 is operatively coupled with a connected processor, transmits and/or receives radio signals or wireline signals. The UE 10a may be in communication with the UE 10b through a sidelink. The base station 200a may be an eNB, a gNB, or one of other types of radio nodes, and may configure radio resources and for the UE 10a and UE 10b.

Each of the

processors

11a, 11b, 201a, and 301 may include application-specific integrated circuits (ASICs) , other chipsets, logic circuits and/or data processing devices. Each of the

memory

12a, 12b, 202a, and 302 may include read-only memory (ROM) , a random access memory (RAM) , a flash memory, a memory card, a storage medium and/or other storage devices. Each of the

transceivers

13a, 13b, 203a, and 303 may include baseband circuitry and radio frequency (RF) circuitry to process radio frequency signals. When the embodiments are implemented in software, the techniques described herein can be implemented with modules, procedures, functions, entities and so on, that perform the functions described herein. The modules can be stored in a memory and executed by the processors. The memory can be implemented within a processor or external to the processor, in which those can be communicatively coupled to the processor via various means are known in the art.

The network entity device 300 may be a node in a CN. CN may include LTE CN or 5G core (5GC) which includes user plane function (UPF) , session management function (SMF) , mobility management function (AMF) , unified data management (UDM) , policy control function (PCF) , control plane (CP) /user plane (UP) separation (CUPS) , authentication server (AUSF) , network slice selection function (NSSF) , and the network exposure function (NEF) .

Rating RATs supported by the IMS:

With reference to FIG. 2, an example of a UE in the description may include one of the UE 10a or UE 10b. An example of a base station in the description may include the base station 200a. Uplink (UL) transmission of a control signal or data may be a transmission operation from a UE to a base station. Downlink (DL) transmission of a control signal or data may be a transmission operation from a base station to a UE. Terms entities used in the FIG. 2 is listed in the following:

UE: User equipment

LTE/NR: Long term evolution or new radio.

PGW/5GC: Public data network (PDN) gateway (PGW) or fifth-generation core.

IMS: Internet protocol (IP) multimedia subsystem (IMS) .

WLAN AP: Wireless local area network (WLAN) access point (AP) .

ePDG: Evolved packet data gateway.

IPSec: Internet Protocol security (IPsec) .

P-CSCF: Proxy call session control function.

Operations between entities are detailed in the following:

1. A UE 10 performs an attach or registration procedure on LTE or NR with a base station 20 (step 101) .

2. The UE 10 initiates an IMS PDN session or a PDU session on LTE or NR respectively with PGW/5GC 30 (step 102) .

3. The UE 10 performs IMS registration procedures through P-CSCF with an IMS 31 (step 103) .

4. The UE 10 initiates handover to WLAN through a WLAN AP 21 based on WLAN availability and call preference (step 104) .

5. The UE 10 sets up an IPSec tunnel with an ePDG server 32 (step 105) .

6. Re-registration to IMS 31 using new RAT is performed (step 106) . The step is an IMS registration retry and may fail due to no response from the ePDG server 32.

7. The UE 10 remains un-registered with the IMS 31 and may retry over WLAN again and again (step 107) . However, the ePDG server 32 not responding is the root cause, so retry will not help.

An embodiment of the invention provides a solution to switch RAT for retry of IMS registration and prioritize RATs for future use. Specifically, the UE 10 rates all RATs supported by the IMS 31 based on preference and adjust the rating of the RATs based on IMS registration result.

With reference to FIG. 3, the UE 10 executes a method for selecting a RAT for registration to an IMS, such as the IMS 31. The UE 10 obtains a plurality of RATs rated in a first arrangement (block 310) .

The plurality of RATs may comprise a set of one or more cellular RATs and a set of one or more non-cellular RATs. The set of one or more cellular RATs comprises one or more of a 5G new radio (NR) system, a 4G long term evolution (LTE) system, a 3G universal mobile telecommunication system (UMTS) , and a 2G global system for mobile communication (GSM) . The set of one or more non-cellular RATs comprise a wireless local area network (WLAN) . The UE 10 can generate a pre-defined RAT list supported by the IMS 31 for IMS registration based on either or both of operator requirements and user preference. The pre-defined RAT list may comprise the plurality of RATs rated in the first arrangement based on either or both of operator requirements and user preference. For example, the list may comprise:

1, WLAN;

2, LTE; and

3, NR.

The WLAN is rated the first in the list means that if WLAN is available and preferred, the UE 10 selects the WLAN for IMS registration.

The UE 10 selects a first RAT from the plurality of RATs as a selected RAT according to the first arrangement (block 312) and uses the selected RAT to perform a first attempt of IMS registration to the IMS 31 (block 314) . The UE 10 may use the highest priority RAT in the list for IMS registration first. The UE 10 rates the first RAT in the plurality of RATs according to a result of the first attempt of IMS registration (block 316) . The UE 10 may dynamically adjust the list through the rating in block 316 based on the IMS registration result.

With reference to FIG. 4, the rating the first RAT in the plurality of RATs further comprises rating down the first RAT in the plurality of RATs when the first attempt of IMS registration is not successful.

The UE 10 determines whether the first attempt of IMS registration is successful (block 316-1) and rates down the first RAT in the plurality of RATs when the first attempt of IMS registration is not successful (block 316-2) . For example, if the UE 10 failed IMS registration over the first RAT, such as WLAN, for a certain number of times, the UE 10 rates down the first RAT. For example, the list adjusted by the rating in block 316-2 may comprise:

1, LTE;

2, WLAN; and

3, NR.

With reference to FIG. 5, the rating the first RAT in the plurality of RATs further comprises rating up the first RAT in the plurality of RATs when the first attempt of IMS registration is successful. The UE 10 determines whether the first attempt of IMS registration is successful (block 316-1a) and rates up the first RAT in the plurality of RATs when the first attempt of IMS registration is successful (block 316-2a) . For example, if the UE 10 succeeds IMS registration over the first RAT, such as LTE, for a certain number of times, the UE 10 rates up the first RAT. For example, the list adjusted by the rating in block 316-2a may comprise:

1, LTE;

2, WLAN; and

3, NR.

RAT switching for IMS registration:

The UE 10 may switch RAT for IMS registration. When the UE 10 failed IMS registration for certain time or a count of attempts with the currently selected RAT, the UE 10 may switch to a next RAT in the list to retry IMS registration.

With reference to FIG. 6, the UE 10 executes a method for selecting a RAT for registration to an IMS, such as the IMS 31. The UE 10 obtains a plurality of RATs rated in a first arrangement (block 310) .

The UE 10 selects a first RAT from the plurality of RATs as a selected RAT according to the first arrangement (block 312) and uses the selected RAT to perform an attempt of IMS registration to the IMS 31 (block 314a) . The UE 10 may use the highest priority RAT, such as the WLAN, in the list for IMS registration first.

The UE 10 determines whether the attempt of IMS registration is successful (block 316-1b) . When the attempt of IMS registration is successful, the UE 10 terminates the method. When the attempt of IMS registration is not successful, the UE 10 selects a second RAT from the plurality of RATs as the selected RAT according to the first arrangement (block 316-2b) . The UE rates down the previously selected RAT, i.e. the first RAT, in the plurality of RATs when the attempt of IMS registration is not successful (block 316-3b) . The plurality of RATs are rearranged in a second arrangement through the rating down of the first RAT. Alternatively, the UE 10 may rate up the first RAT in the plurality of RATs to obtain an alternative arrangement of the RATs when the second attempt of IMS registration is successful.

The UE 10 uses the selected RAT to perform a second attempt of IMS registration (block 314a) and rates the second RAT in the plurality of RATs according to a result of the second attempt of IMS registration. The UE 10 determines whether the second attempt of IMS registration is successful (block 316-1b) . When the second attempt of IMS registration is successful, the UE 10 terminates the method. When the second attempt of IMS registration is not successful, the UE 10 selects a third RAT from the plurality of RATs as the selected RAT according to the second arrangement (block 316-2b) . The UE rates down reviously selected RAT, i.e. the second RAT, in the plurality of RATs when the second attempt of IMS registration is not successful (block 316-3b) . The plurality of RATs are rearranged in a third arrangement through the rating down of the second RAT. Alternatively, the UE 10 may rate up the second RAT in the plurality of RATs to obtain an alternative arrangement of RATs when the second attempt of IMS registration is successful.

The UE 10 uses the selected RAT, i.e. the third RAT, to perform a third attempt of IMS registration (block 314a) . The operations in the method continue until the method terminates.

RAT blacklist and disabling:

The UE 10 may use a blacklist of RATs to disable a specific RAT that causes continuous or concurrent IMS registration failures.

With reference to FIG. 7, the UE 10 executes a method for selecting a RAT for registration to an IMS, such as the IMS 31. The UE 10 obtains a plurality of RATs rated in a first arrangement (block 310) .

The UE 10 selects a first RAT from the plurality of RATs as a selected RAT according to the first arrangement, where the first RAT is not disabled and not included in a RAT backlist (block 312c) . The UE 10 uses the selected RAT to perform an attempt of IMS registration to the IMS 31 (block 314c) . The UE 10 may use the highest priority RAT, such as the WLAN or LTE in the aforementioned example of lists, in the list for IMS registration first.

The UE 10 determines whether the attempt of IMS registration is successful (block 316-1c) . When the attempt of IMS registration is successful, the UE 10 terminates the method. When the attempt of IMS registration is not successful, the UE 10 selects a next RAT, such as the second RAT, from the plurality of RATs as the selected RAT according to the first arrangement, where the next RAT is not disabled and not included in the RAT backlist. (block 316-2c) . The UE rates down the previously selected RAT, i.e. the first RAT, in the plurality of RATs when the attempt of IMS registration is not successful (block 316-3c) . The plurality of RATs are rearranged in a second arrangement through the rating down of the first RAT. Alternatively, the UE 10 may rate up the previously selected RAT, i.e. the first RAT, in the plurality of RATs to obtain an alternative arrangement of the RATs when the second attempt of IMS registration is successful.

The UE 10 determines whether the previously selected RAT, such as the first RAT, fails a certain number N1 of IMS registration attempts, where the certain number of IMS registration attempts is greater than a threshold T1 (block 319) . The UE 10 adds the previously selected RAT to a RAT blacklist to disable the previously selected RAT (block 320) and sets a RAT disabling timer associated with the disabled RAT (block 322) when the previously selected RAT fails a certain number N1 of IMS registration attempts, wherein the disabled RAT, such as the first RAT, in the blacklist is banned from be used for IMS registration.

The UE 10 uses the selected RAT to perform a second attempt of IMS registration (block 314c) and rates the selected RAT, such as the second RAT, in the plurality of RATs according to a result of the second attempt of IMS registration. The UE 10 determines whether the second attempt of IMS registration is successful (block 316-1c) . When the second attempt of IMS registration is successful, the UE 10 terminates the method. When the second attempt of IMS registration is not successful, the UE 10 selects a third RAT from the plurality of RATs as the selected RAT according to the second arrangement, where the third RAT is not disabled and not included in a RAT backlist (block 316-2c) . The UE rates down the second RAT in the plurality of RATs when the second attempt of IMS registration is not successful (block 316-3c) . The plurality of RATs are rearranged in a third arrangement through the rating down of the second RAT. Alternatively, the UE 10 may rate up the second RAT in the plurality of RATs to obtain an alternative arrangement of RATs when the second attempt of IMS registration is successful.

The UE 10 determines whether the previously selected RAT, such as the second RAT, fails a certain number N1 of IMS registration attempts, where the certain number N1 of IMS registration attempts is greater than a threshold T1 (block 319) .

The UE 10 adds the previously selected RAT, such as the second RAT, to a RAT blacklist to disable the previously selected RAT (block 320) and sets a RAT disabling timer associated with the disabled RAT (block 322) when the previously selected RAT fails a certain number N1 of IMS registration attempts, wherein the disabled RAT in the blacklist is banned from be used for IMS registration.

With reference to FIG. 8, the UE 10 detects expiration of the RAT disabling timer associated with the disabled RAT, such as the first RAT or the second RAT (block 330) . The UE 10 removes the disabled RAT from the blacklist upon expiration of the RAT disabling timer associated with the disabled RAT (block 332) .

In the embodiment of the invention, when reaching the certain number N1 of IMS registration failures through a network, such as WLAN or a radio access network (RAN) of a PLMN, the UE 10 may disable the WLAN or the RAN of the PLMN for IMS registration for a certain time.

If UE meets IMS registration failure over the WLAN for certain times, the UE 10 may add the WLAN into the RAT blacklist and start a timer T _disable-WLAN associated with the WLAN. Before the timer expires, the UE 10 will not consider the WLAN for IMS registration. After T _disable-WLAN expired, UE can remove the WLAN from the RAT blacklist. The embodiment may be applied to other RATs in the list, such as LTE and NR. If UE meets IMS registration failure over the NR for certain times, the UE 10 may add the NR into the RAT blacklist and start a timer T _disable-NR associated with the NR RAT. Before the timer expires, the UE 10 will not consider the NR for IMS registration. After T _disable-NR expired, UE can remove the NR from the RAT blacklist.

Disable IMS:

The UE 10 may disable the IMS 31 for IMS registration if needed to retry the call in circuit switch (CS) . If UE could not register IMS over all supported RATs for a certain number N2 of rounds that is greater than a threshold T2, the UE 10 may disable IMS features completely to allow a call to go through a CS domain. The UE 10 may start a timer T _disable-IMS to time the disabling of the IMS 31. After T _disable-IMS expires, the UE 10 may enable the IMS 31.

With reference to FIG. 9, the UE 10 determines whether unsuccessful attempts of registration to the IMS reach a number of rounds N2 that is greater than a threshold T2 (block 340) . The UE 10 disables any additional attempt of IMS registration to the IMS and sets a IMS disabling timer T _disable-IMS associated with the IMS when unsuccessful attempts of registration to the IMS reach a number of rounds N2 that is greater than a threshold T2 (block 342) .

The UE 10 enables an additional attempt of IMS registration to the IMS 31 upon expiration of the IMS disabling timer T _disable-IMS associated with the IMS 31 (block 344) .

FIG. 10 is a block diagram of an example system 700 for wireless communication according to an embodiment of the present disclosure. Embodiments described herein may be implemented into the system using any suitably configured hardware and/or software. FIG. 10 illustrates the system 700 including a radio frequency (RF) circuitry 710, a baseband circuitry 720, a processing unit 730, a memory/storage 740, a display 750, a camera 760, a sensor 770, and an input/output (I/O) interface 780, coupled with each other as illustrated.

The processing unit 730 may include circuitry, such as, but not limited to, one or more single-core or multi-core processors. The processors may include any combinations of general-purpose processors and dedicated processors, such as graphics processors and application processors. The processors may be coupled with the memory/storage and configured to execute instructions stored in the memory/storage to enable various applications and/or operating systems running on the system.

The baseband circuitry 720 may include circuitry, such as, but not limited to, one or more single-core or multi-core processors. The processors may include a baseband processor. The baseband circuitry may handle various radio control functions that enable communication with one or more radio networks via the RF circuitry. The radio control functions may include, but are not limited to, signal modulation, encoding, decoding, radio frequency shifting, etc. In some embodiments, the baseband circuitry may provide for communication compatible with one or more radio technologies. For example, in some embodiments, the baseband circuitry may support communication with 5G NR, LTE, an evolved universal terrestrial radio access network (EUTRAN) and/or other wireless metropolitan area networks (WMAN) , a wireless local area network (WLAN) , a wireless personal area network (WPAN) . Embodiments in which the baseband circuitry is configured to support radio communications of more than one wireless protocol may be referred to as multi-mode baseband circuitry. In various embodiments, the baseband circuitry 720 may include circuitry to operate with signals that are not strictly considered as being in a baseband frequency. For example, in some embodiments, baseband circuitry may include circuitry to operate with signals having an intermediate frequency, which is between a baseband frequency and a radio frequency.

The RF circuitry 710 may enable communication with wireless networks using modulated electromagnetic radiation through a non-solid medium. In various embodiments, the RF circuitry may include switches, filters, amplifiers, etc. to facilitate the communication with the wireless network. In various embodiments, the RF circuitry 710 may include circuitry to operate with signals that are not strictly considered as being in a radio frequency. For example, in some embodiments, RF circuitry may include circuitry to operate with signals having an intermediate frequency, which is between a baseband frequency and a radio frequency.

In various embodiments, the transmitter circuitry, control circuitry, or receiver circuitry discussed above with respect to the UE, eNB, or gNB may be embodied in whole or in part in one or more of the RF circuitries, the baseband circuitry, and/or the processing unit. As used herein, “circuitry” may refer to, be part of, or include an Application Specific Integrated Circuit (ASIC) , an electronic circuit, a processor (shared, dedicated, or group) , and/or memory (shared, dedicated, or group) that execute one or more software or firmware programs, a combinational logic circuit, and/or other suitable hardware components that provide the described functionality. In some embodiments, the electronic device circuitry may be implemented in, or functions associated with the circuitry may be implemented by, one or more software or firmware modules. In some embodiments, some or all of the constituent components of the baseband circuitry, the processing unit, and/or the memory/storage may be implemented together on a system on a chip (SOC) .

The memory/storage 740 may be used to load and store data and/or instructions, for example, for the system. The memory/storage for one embodiment may include any combination of suitable volatile memory, such as dynamic random access memory (DRAM) ) , and/or non-volatile memory, such as flash memory. In various embodiments, the I/O interface 780 may include one or more user interfaces designed to enable user interaction with the system and/or peripheral component interfaces designed to enable peripheral component interaction with the system. User interfaces may include, but are not limited to a physical keyboard or keypad, a touchpad, a speaker, a microphone, etc. Peripheral component interfaces may include, but are not limited to, a non-volatile memory port, a universal serial bus (USB) port, an audio jack, and a power supply interface.

In various embodiments, the sensor 770 may include one or more sensing devices to determine environmental conditions and/or location information related to the system. In some embodiments, the sensors may include, but are not limited to, a gyro sensor, an accelerometer, a proximity sensor, an ambient light sensor, and a positioning unit. The positioning unit may also be part of, or interact with, the baseband circuitry and/or RF circuitry to communicate with components of a positioning network, e.g., a global positioning system (GPS) satellite. In various embodiments, the display 750 may include a display, such as a liquid crystal display and a touch screen display. In various embodiments, the system 700 may be a mobile computing device such as, but not limited to, a laptop computing device, a tablet computing device, a netbook, an ultrabook, a smartphone, etc. In various embodiments, the system may have more or fewer components, and/or different architectures. Where appropriate, the methods described herein may be implemented as a computer program. The computer program may be stored on a storage medium, such as a non-transitory storage medium.

The embodiment of the present disclosure is a combination of techniques/processes that can be adopted in 3GPP specification to create an end product.

A person having ordinary skill in the art understands that each of the units, algorithm, and steps described and disclosed in the embodiments of the present disclosure are realized using electronic hardware or combinations of software for computers and electronic hardware. Whether the functions run in hardware or software depends on the condition of application and design requirement for a technical plan. A person having ordinary skill in the art can use different ways to realize the function for each specific application while such realizations should not go beyond the scope of the present disclosure. It is understood by a person having ordinary skill in the art that he/she can refer to the working processes of the system, device, and unit in the above-mentioned embodiment since the working processes of the above-mentioned system, device, and unit are basically the same. For easy description and simplicity, these working processes will not be detailed.

It is understood that the disclosed system, device, and method in the embodiments of the present disclosure can be realized in other ways. The above-mentioned embodiments are exemplary only. The division of the units is merely based on logical functions while other divisions exist in realization. It is possible that a plurality of units or components are combined or integrated into another system. It is also possible that some characteristics are omitted or skipped. On the other hand, the displayed or discussed mutual coupling, direct coupling, or communicative coupling operate through some ports, devices, or units whether indirectly or communicatively by ways of electrical, mechanical, or other kinds of forms.

The units as separating components for explanation are or are not physically separated. The units for display are or are not physical units, that is, located in one place or distributed on a plurality of network units. Some or all of the units are used according to the purposes of the embodiments. Moreover, each of the functional units in each of the embodiments can be integrated into one processing unit, physically independent, or integrated into one processing unit with two or more than two units.

If the software function unit is realized and used and sold as a product, it can be stored in a readable storage medium in a computer. Based on this understanding, the technical plan proposed by the present disclosure can be essentially or partially realized as the form of a software product. Or, one part of the technical plan beneficial to the conventional technology can be realized as the form of a software product. The software product in the computer is stored in a storage medium, including a plurality of commands for a computational device (such as a personal computer, a server, or a network device) to run all or some of the steps disclosed by the embodiments of the present disclosure. The storage medium includes a USB disk, a mobile hard disk, a read-only memory (ROM) , a random access memory (RAM) , a floppy disk, or other kinds of media capable of storing program codes.

While the present disclosure has been described in connection with what is considered the most practical and preferred embodiments, it is understood that the present disclosure is not limited to the disclosed embodiments but is intended to cover various arrangements made without departing from the scope of the broadest interpretation of the appended claims.

Claims

A method for selecting a radio access technology (RAT) for registration to an Internet protocol (IP) multimedia subsystem (IMS) , executable in a wireless device, comprising:

obtaining a plurality of RATs rated in a first arrangement;

selecting a first RAT from the plurality of RATs as a selected RAT according to the first arrangement;

using the selected RAT to perform a first attempt of IMS registration; and

rating the first RAT in the plurality of RATs according to a result of the first attempt of IMS registration.
The method of claim 1, wherein the plurality of RATs comprise a set of one or more cellular RATs and a set of one or more non-cellular RATs.
The method of claim 2, wherein the set of one or more cellular RATs comprises one or more of:

a new radio (NR) system;

a long term evolution (LTE) system; and

a global system for mobile communication (GSM) ; and

a universal mobile telecommunication system (UMTS) ;

wherein the set of one or more non-cellular RATs comprise a wireless local area network (WLAN) .
The method of claim 1, wherein the rating the first RAT in the plurality of RATs further comprises:

rating down the first RAT in the plurality of RATs when the first attempt of IMS registration is not successful; or

rating up the first RAT in the plurality of RATs when the first attempt of IMS registration is successful.
The method of claim 4, further comprising:

selecting a second RAT from the plurality of RATs as the selected RAT according to the first arrangement when the first attempt of IMS registration is not successful;

using the selected RAT to perform a second attempt of IMS registration; and

rating the second RAT in the plurality of RATs according to a result of the second attempt of IMS registration.
The method of claim 5, wherein the rating the second RAT in the plurality of RATs further comprises:

rating down the second RAT in the plurality of RATs when the second attempt of IMS registration is not successful; or

rating up the second RAT in the plurality of RATs when the second attempt of IMS registration is successful.
The method of claim 4, further comprising:

adding the first RAT to a blacklist and setting a RAT disabling timer associated with the first RAT when the first RAT fails a certain number of IMS registration attempts that is greater than a threshold T1, wherein the first RAT in the blacklist is banned from be used for IMS registration; and

removing the first RAT from the blacklist upon expiration of the RAT disabling timer associated with the first RAT.
The method of claim 4, further comprising:

disabling any additional attempt of IMS registration to the IMS and setting a IMS disabling timer associated with the IMS when unsuccessful attempts of registration to the IMS reaches a number of rounds N2 that is greater than a threshold T2; and

enabling an additional attempt of IMS registration to the IMS upon expiration of the IMS disabling timer associated with the IMS.
A wireless device for selecting a radio access technology (RAT) for registration to an Internet protocol (IP) multimedia subsystem (IMS) , comprising:

a transceiver; and

a processor connected to the transceiver and configured to execute steps of:

obtaining a plurality of RATs rated in a first arrangement;

selecting a first RAT from the plurality of RATs as a selected RAT according to the first arrangement;

using the selected RAT to perform a first attempt of IMS registration; and

rating the first RAT in the plurality of RATs according to a result of the first attempt of IMS registration.
The wireless device of claim 9, wherein the plurality of RATs comprise a set of one or more cellular RATs and a set of one or more non-cellular RATs.
The wireless device of claim 10, wherein the set of one or more cellular RATs comprises one or more of:

a new radio (NR) system;

a long term evolution (LTE) system; and

a global system for mobile communication (GSM) ; and

a universal mobile telecommunication system (UMTS) ;

wherein the set of one or more non-cellular RATs comprise a wireless local area network (WLAN) .
The wireless device of claim 9, wherein the rating the first RAT in the plurality of RATs further comprises:

rating down the first RAT in the plurality of RATs when the first attempt of IMS registration is not successful; or

rating up the first RAT in the plurality of RATs when the first attempt of IMS registration is successful.
The wireless device of claim 12, wherein the processor is further configured to execute:

selecting a second RAT from the plurality of RATs as the selected RAT according to the first arrangement when the first attempt of IMS registration is not successful;

using the selected RAT to perform a second attempt of IMS registration; and

rating the second RAT in the plurality of RATs according to a result of the second attempt of IMS registration.
The wireless device of claim 13, wherein the rating the second RAT in the plurality of RATs further comprises:

rating down the second RAT in the plurality of RATs when the second attempt of IMS registration is not successful; or

rating up the second RAT in the plurality of RATs when the second attempt of IMS registration is successful.
The wireless device of claim 12, wherein the processor is further configured to execute:

adding the first RAT to a blacklist and setting a RAT disabling timer associated with the first RAT when the first RAT fails a certain number of IMS registration attempts that is greater than a threshold T1, wherein the first RAT in the blacklist is banned from be used for IMS registration; and

removing the first RAT from the blacklist upon expiration of the RAT disabling timer associated with the first RAT.
The wireless device of claim 12, wherein the processor is further configured to execute:

disabling any additional attempt of IMS registration to the IMS and setting a IMS disabling timer associated with the IMS when unsuccessful attempts of registration to the IMS reaches a number of rounds N2 that is greater than a threshold T2; and

enabling an additional attempt of IMS registration to the IMS upon expiration of the IMS disabling timer associated with the IMS.
A chip, comprising:

a processor, configured to call and run a computer program stored in a memory, to cause a device in which the chip is installed to execute any of the methods of claims 1 to 8.
A computer readable storage medium, in which a computer program is stored, wherein the computer program causes a computer to execute any of the methods of claims 1 to 8.
A computer program product, comprising a computer program, wherein the computer program causes a computer to execute any of the methods of claims 1 to 8.
A computer program, wherein the computer program causes a computer to execute any of the methods of claims 1 to 8