CN114401537B

CN114401537B - Network redirection method, device and user equipment

Info

Publication number: CN114401537B
Application number: CN202210291840.2A
Authority: CN
Inventors: 魏珍荣
Original assignee: Honor Device Co Ltd
Current assignee: Honor Device Co Ltd
Priority date: 2022-03-24
Filing date: 2022-03-24
Publication date: 2022-08-19
Anticipated expiration: 2042-03-24
Also published as: CN114401537A

Abstract

The embodiment of the application provides a network redirection method, a network redirection device and user equipment. The following technical scheme is specifically disclosed: when the user equipment is redirected to the network, searching a target cell on a target frequency point appointed by a network side; and if the public land mobile network PLMN of the target cell is the unidentified PLMN, the user equipment takes the target cell as a cell of an equivalent public land mobile network EPLMN and initiates network registration to the target cell. According to the technical scheme, when the user equipment redirects the network, if the searched target cell belongs to the unidentified PLMN, the target cell is used as the cell of the RPLMN to initiate network registration, so that the problem of network redirection failure caused by the fact that the user equipment cannot initiate network registration to the unidentified PLMN in the prior art is solved.

Description

Network redirection method, device and user equipment

Technical Field

The embodiment of the application relates to the technical field of communication, in particular to a network redirection method, a network redirection device and user equipment.

Background

With the influence of the factors such as the continuous update of the network system, the network planning change of each operator, the construction of the different network roaming, etc., the operator may add a new PLMN on the basis of the original PLMN, thereby adding a new PLMN identifier. The newly added PLMN identities, in particular PLMN identities still in the testing phase, which have not been formally used by the operator, may not be recognized by some user equipments as belonging to unidentified PLMNs.

According to the existing protocol, the user equipment initiates registration to the unidentified PLMN only under the condition of no network, and in the network redirection scene, the registration cannot be initiated to the unidentified PLMN, so that the network redirection fails, and the user equipment returns to the RPLMN again. After that, when the network side initiates the network redirection again, the user equipment will search for the unidentified PLMN again, and then the network redirection fails again, and the user equipment returns to the RPLMN again. Thus, the user equipment may cycle repeatedly between network redirection-redirection failure, resulting in its failure to use the network normally at all times.

Disclosure of Invention

The embodiment of the application provides a network redirection method, a network redirection device and user equipment, which are used for solving the problem that network redirection of the user equipment fails due to unidentified PLMN.

In a first aspect, an embodiment of the present application provides a network redirection method, including: when the user equipment is redirected to the network, searching a target cell on a target frequency point appointed by a network side; and if the public land mobile network PLMN of the target cell is the unidentified PLMN, the user equipment takes the target cell as the cell of the equivalent public land mobile network EPLMN and initiates network registration to the target cell.

According to the technical scheme, when the user equipment redirects the network, if the searched target cell belongs to the unidentified PLMN, the target cell is taken as the cell of the RPLMN to initiate the network registration, so that the problem of network redirection failure caused by the fact that the user equipment cannot initiate the network registration to the unidentified PLMN in the prior art is solved.

In one implementation manner, after the user equipment initiates network registration to the target cell, the method further includes: the user equipment judges whether the network registration is successful; if the network registration is successful, the user equipment judges whether the service abnormality exists in the preset duration after the network registration is successful; and if the service is abnormal, the user equipment forbids the PLMN of the target cell and/or forbids the network system corresponding to the PLMN of the target cell. In this way, the user equipment will not initiate network registration with the cell of the PLMN thereafter, thereby avoiding the problem of network registration success but service unavailability from recurring.

In one implementation, the method further comprises: and if the network registration fails, the user equipment disables the PLMN of the target cell and/or disables the network system corresponding to the PLMN of the target cell. Therefore, the user equipment does not initiate network registration to the cell of the PLMN any more, and repeated network registration failure is avoided.

In one implementation, the method further comprises: if no service abnormality exists, the user equipment resides in the target cell, and the PLMN of the target cell is determined as the EPLMN. Thus, if the user equipment searches the target cell again in the later network redirection, the network registration can be directly initiated to the target cell according to the existing protocol.

In one implementation, if the PLMN of the target cell is an unidentified PLMN, the user equipment regards the target cell as a cell of the EPLMN and initiates network registration to the target cell, including: the user equipment judges whether the PLMN identification of the PLMN of the target cell exists in a preset PLMN white list, wherein the PLMN white list comprises the PLMN identifications of a plurality of PLMNs; if the PLMN identification of the PLMN of the target cell exists in the PLMN white list, the user equipment judges whether other cells are searched on the target frequency point; and if other cells are not searched on the target frequency point, the user equipment takes the target cell as the EPLMN cell and initiates network registration to the target cell. Therefore, the user equipment can judge whether the PLMN of the target cell is the newly added PLMN according to the PLMN white list, and initiate network registration to the target cell when determining whether the PLMN of the target cell is the newly added PLMN and other cells are not searched on the target frequency point.

In one implementation, the method further comprises: and if the service abnormity does not exist, the user equipment displays the operator name of the PLMN of the target cell as the operator name of the Registered Public Land Mobile Network (RPLMN).

In one implementation, the disabling, by the user equipment, the PLMN of the target cell, and/or the network standard corresponding to the PLMN of the target cell includes: if the network redirection is the redirection between the same systems, the user equipment disables the PLMN of the target cell; if the network redirection is the redirection between different systems, the user equipment disables the PLMN of the target cell, and disables the network system corresponding to the PLMN of the target cell under the target cell. Therefore, when the network redirection is the redirection between the same systems, the user equipment cannot redirect to the unidentified PLMN again, and when the network redirection is the redirection between the same systems, the user equipment cannot redirect to the new network standard corresponding to the unidentified PLMN again, so that the problem that the network fails to orient again is avoided.

In one implementation, the method further comprises: when user equipment initiates network registration to a target cell, a registration timer is started; if the user equipment receives a registration completion message of the network side, the user equipment determines that the network registration is successful; if the user equipment receives a registration rejection message of the network side, or if the registration timer has timed out but the user equipment does not receive a registration completion message of the network side, the user equipment determines that the network registration fails.

In a second aspect, an embodiment of the present application provides a network redirection device, including: the searching unit is used for searching a target cell on a target frequency point appointed by a network side when the network is redirected; and the registration unit is used for taking the target cell as the EPLMN cell and initiating network registration to the target cell if the PLMN of the target cell is the unidentified PLMN.

In one implementation, the apparatus further comprises: a first judgment unit, configured to judge whether network registration is successful; the second judgment unit is used for judging whether the service abnormity exists in the preset time after the network registration is successful or not if the network registration is successful; and the execution unit is used for forbidding the PLMN of the target cell and/or forbidding the network system corresponding to the PLMN of the target cell if the service abnormity exists. In this way, the user equipment will not initiate network registration with the cell of the PLMN thereafter, thereby avoiding the problem of network registration success but service unavailability from recurring.

In one implementation, the execution unit is further configured to disable the PLMN of the target cell and/or disable the network type corresponding to the PLMN of the target cell if the network registration fails. Therefore, the user equipment does not initiate network registration to the cell of the PLMN any more, thereby avoiding repeated network registration failure.

In one implementation, the execution unit is further configured to camp on the target cell if there is no traffic anomaly, and determine the PLMN of the target cell as the EPLMN. Thus, if the user equipment searches the target cell again in the later network redirection, the network registration can be directly initiated to the target cell according to the existing protocol.

In one implementation, the apparatus further comprises: a third determining unit, configured to determine whether a PLMN identifier of a PLMN of the target cell exists in a preset PLMN white list, where the PLMN white list includes PLMN identifiers of multiple PLMNs; a fourth judging unit, configured to judge whether other cells are searched on the target frequency point if the PLMN identifier of the PLMN of the target cell exists in the PLMN white list; and the registration unit is specifically used for taking the target cell as the EPLMN cell and initiating network registration to the target cell if other cells are not searched on the target frequency point. Therefore, the user equipment can judge whether the PLMN of the target cell is the newly added PLMN according to the PLMN white list, and initiate network registration to the target cell when determining whether the PLMN of the target cell is the newly added PLMN and other cells are not searched on the target frequency point.

In one implementation, the execution unit is further configured to display an operator name of the PLMN of the target cell as an operator name of the registered public land mobile network RPLMN if there is no traffic anomaly.

In an implementation manner, when the execution unit is configured to disable the PLMN of the target cell and/or disable the network standard corresponding to the PLMN of the target cell, the method specifically includes: if the network redirection is the redirection between the same systems, the user equipment disables the PLMN of the target cell; if the network redirection is the redirection between different systems, the user equipment disables the PLMN of the target cell, and disables the network system corresponding to the PLMN of the target cell under the target cell. Thus, when the network redirection is the redirection between the same systems, the user equipment cannot be redirected to the unidentified PLMN again, and when the network redirection is the redirection between the same systems, the user equipment cannot be redirected to the new network standard corresponding to the unidentified PLMN again, so that the problem that the network fails to be oriented again is avoided.

In one implementation manner, the first determining unit is specifically configured to: when user equipment initiates network registration to a target cell, starting a registration timer; if the user equipment receives a registration completion message of a network side, determining that the network registration is successful; if the user equipment receives the registration rejection message of the network side, or if the registration timer has timed out but the user equipment does not receive the registration completion message of the network side, the network registration is determined to be failed.

In a third aspect, an embodiment of the present application provides a user equipment, including: a processor and a memory; the memory stores program instructions that, when executed by the processor, cause the user equipment to perform the above aspects and methods in its various implementations.

In a fourth aspect, embodiments of the present application further provide a chip system, where the chip system includes a processor and a memory, and the memory stores program instructions, and when the program instructions are executed by the processor, the chip system is caused to perform the methods in the foregoing aspects and their respective implementations. For example, information involved in the above-described methods is generated or processed.

In a fifth aspect, embodiments of the present application further provide a computer-readable storage medium, in which program instructions are stored, and when the program instructions are executed on a computer, the computer is caused to execute the methods in the foregoing aspects and their respective implementation manners.

In a sixth aspect, the present application further provides a computer program product, which when run on a computer, causes the computer to execute the method in the above aspects and their respective implementation manners.

Drawings

Fig. 1 is a diagram of a scenario in which an unidentified PLMN causes a failure in network redirection of a user equipment;

FIG. 2 is a schematic diagram of a network system for implementing a network redirection method of an embodiment of the present application;

fig. 3 is a schematic structural diagram of a user equipment provided in an embodiment of the present application;

fig. 4 is a flowchart of a network redirection method provided in an embodiment of the present application;

fig. 5 is a more specific flowchart of a network redirection method provided in an embodiment of the present application;

fig. 6 is a flowchart illustrating a network registration failure according to an embodiment of the present application;

fig. 7 is another flow chart illustrating a network registration failure according to an embodiment of the present application;

fig. 8 is a flowchart of the network redirection method implemented in the present application when the network registration of the user equipment is successful and the service is normal;

fig. 9 is a flowchart of a network redirection method according to an embodiment of the present application when network registration of a user equipment is successful but a service is abnormal;

fig. 10 is a schematic structural diagram of a network redirection device according to an embodiment of the present application;

fig. 11 is a schematic structural diagram of another network redirection device provided in an embodiment of the present application.

Detailed Description

In the embodiments of the present application, the words "exemplary" or "such as" are used herein to mean serving as an example, instance, or illustration. Any embodiment or design described herein as "exemplary" or "e.g.," is not necessarily to be construed as preferred or advantageous over other embodiments or designs. Rather, use of the word "exemplary" or "such as" is intended to present concepts related in a concrete fashion.

The terminology used in the description of the embodiments section of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application, which will be described in detail below with reference to the accompanying drawings.

A Public Land Mobile Network (PLMN) is a network established and operated by a government or government-approved network operator for the purpose of providing land mobile services to the public. PLMNs provided by different operators may be distinguished by different PLMN identities (also called net numbers), each operator having one or more PLMN identities belonging to them. The PLMN identity is generally composed of a mobile equipment country code (MCC) and a mobile equipment network code (MNC). The MCC generally consists of 3 digits and is used to identify the country to which the mobile device belongs, for example, MCC in china includes 460 and 461. The MNC is generally composed of 2 digits and is used to identify the operator to which the mobile device belongs, for example, MNCs for china mobile include 00, 02, etc. Thus, the full PLMN identity contains 5 digits, e.g., 46000, 46002, etc.

According to the definition of 3GPP technical specification 36.300, PLMNs include, but are not limited to, the following types:

a Registered Public Land Mobile Network (RPLMN) refers to a PLMN that a user equipment has successfully registered last time.

An Equivalent Public Land Mobile Network (EPLMN) refers to a PLMN that is co-located with the RPLMN with which the user equipment is currently registered, and has the same priority as the RPLMN.

With the influence of the factors such as the continuous updating of the network system, the network planning change of each operator, the construction of the different network roaming, etc., the operator may add a new PLMN on the basis of the original PLMN, thereby adding a new PLMN identifier. The newly added PLMN identities, in particular some PLMN identities still in the testing phase, which have not been formally used by the operator, may not be recognized by some user equipments. In this case, the new PLMN belongs to an unidentified PLMN for the user equipment. According to existing protocols, the user equipment initiates registration with an unidentified PLMN only in the absence of a network. This may affect the registration and residence of the user equipment in the network.

Fig. 1 is a scenario diagram of a failure of network redirection of a user equipment due to an unidentified PLMN. As shown in fig. 1, when a user equipment registered to a certain PLMN initiates network redirection on a network side, cell search is performed on a frequency point specified by the network side, and an active cell is searched, but the active cell belongs to an unidentified PLMN. According to the existing protocol, the user equipment does not initiate registration to the unidentified PLMN in the network redirection scene, so that redirection failure is caused, and the user equipment returns to the RPLMN again. After that, when the network side initiates network redirection again, the user equipment will search for the unrecognized PLMN again, and then fails redirection again, and returns to the RPLMN again. Thus, the user equipment may cycle repeatedly between network redirection and redirection failure, resulting in the user equipment always not using the network normally.

In order to solve the problem that network redirection of user equipment fails due to unidentified PLMN, the embodiment of the application provides a network redirection method.

Fig. 2 is a schematic diagram of a network system for implementing the network redirection method according to the embodiment of the present application. As shown in fig. 2, the network system may include a user equipment 100 and one or more PLMNs 200. One or more PLMNs 200 (e.g., PLMN 200-1 and PLMN 200-2 in fig. 2) may be PLMNs provided by one or more different operators, and may also be PLMNs corresponding to different wireless communication systems, for example: global system for mobile communications (GSM), General Packet Radio Service (GPRS), Code Division Multiple Access (CDMA), Wideband Code Division Multiple Access (WCDMA), time division code division multiple access (TD-SCDMA), Long Term Evolution (LTE), new air interface for fifth generation mobile communication technology (5G NR), and wireless communication systems of future other technology standards.

Each PLMN 200 may include a plurality of network devices, such as access network (RAN) devices 201 and Core Network (CN) devices 202. The access network device 201 may be a Base Transceiver Station (BTS) in GSM or CDMA, a base station (nodeb, NB) in WCDMA, an evolved node b (eNB or eNodeB) in LTE, or a relay station, an access point, and a network device in future PLMN. The core network device 202 may be a Mobility Management Entity (MME) in LTE, a gateway, and may also be a Network Function (NF) of a Control Plane (CP) and a network function of a User Plane (UP) in a 5G network, such as a common control plane network function (common NF, CCNF), a session management network function (SMF), and the like.

For convenience of description, the network devices in the PLMN are collectively referred to as the network side.

Fig. 3 is a schematic structural diagram of a user equipment according to an embodiment of the present application. As shown in fig. 3, the user equipment 100 may include a processor 110, an external memory interface 120, an internal memory 121, a Universal Serial Bus (USB) interface 130, a charging management module 140, a power management module 141, a battery 142, an antenna 1, an antenna 2, a mobile communication module 150, a wireless communication module 160, an audio module 170, a speaker 170A, a microphone 170B, a microphone 170C, an earphone interface 170D, a sensor module 180, a key 190, a motor 191, an indicator 192, a camera 193, a display screen 194, a SIM card interface 195, and the like. The sensor module 180 may include a pressure sensor 180A, a gyro sensor 180B, an air pressure sensor 180C, a magnetic sensor 180D, an acceleration sensor 180E, a distance sensor 180F, a proximity light sensor 180G, a fingerprint sensor 180H, a temperature sensor 180J, a touch sensor 180K, an ambient light sensor 180L, a bone conduction sensor 180M, and the like.

It is to be understood that the structure illustrated in fig. 3 does not constitute a specific limitation to the user equipment 100. In another embodiment of the present application, the user equipment 100 may include more or fewer components than illustrated, or combine certain components, or split certain components, or a different arrangement of components. The illustrated components may be implemented in hardware, software, or a combination of software and hardware.

Processor 110 may include one or more processing units. For example, the Processor 110 may include an Application Processor (AP), a Modem (Modem), a Graphics Processing Unit (GPU), an Image Signal Processor (ISP), a controller, a video codec, a Digital Signal Processor (DSP), a baseband Processor, and/or a Neural-Network Processing Unit (NPU), and the like. The different processing units may be separate devices or may be integrated in one or more processors.

The charging management module 140 is configured to receive a charging input from a charger. The charger can be a wireless charger or a wired charger.

The power management module 141 is used to connect the battery 142, the charging management module 140 and the processor 110. The power management module 141 receives input from the battery 142 and/or the charge management module 140, and supplies power to the processor 110, the internal memory 121, the display 194, the camera 193, the wireless communication module 160, and the like.

The wireless communication function of the user equipment 100 may be implemented by the antenna 1, the antenna 2, the mobile communication module 150, the wireless communication module 160, a modem, a baseband processor, and the like.

The antennas 1 and 2 are used for transmitting and receiving electromagnetic wave signals. Each antenna in the user equipment 100 may be used to cover a single or multiple communication bands. Different antennas can also be multiplexed to improve the utilization of the antennas.

The mobile communication module 150 may provide a solution including wireless communication of 2G/3G/4G/5G, etc. applied on the user equipment 100.

The Wireless Communication module 160 may provide a solution for Wireless Communication applied to the user equipment 100, including Wireless Local Area Networks (WLANs) (such as Wi-Fi Networks), bluetooth (bluetooth, BT), Global Navigation Satellite System (GNSS), Frequency Modulation (FM), Near Field Communication (NFC), infrared technology, and the like. The wireless communication module 160 may be one or more devices integrating at least one communication processing module. The wireless communication module 160 receives electromagnetic waves via the antenna 2, performs frequency modulation and filtering processing on electromagnetic wave signals, and transmits the processed signals to the processor 110. The wireless communication module 160 may also receive a signal to be transmitted from the processor 110, perform frequency modulation and amplification on the signal, and convert the signal into electromagnetic waves via the antenna 2 to radiate the electromagnetic waves.

In some embodiments, in examples where the wireless communication module 160 provides bluetooth communication, the wireless communication module 160 may specifically be a bluetooth chip. The bluetooth chip may include one or more memories, one or more processors, and the like. The processor in the bluetooth chip can perform operations such as frequency modulation, filtering, operation, and judgment on the electromagnetic wave received by the antenna 2, and convert the processed signal into electromagnetic wave to be radiated by the antenna 2, that is, the processor 110 is not needed for processing.

The wireless communication module 160 or the processor 110 may perform the steps performed by the user equipment 100 in the method provided by the embodiment of the present application, which may specifically refer to the related descriptions of the user equipment 100 in fig. 3 to 11, and are not described herein again.

The user device 100 implements display functions through the GPU, the display screen 194, and the application processor, etc. The GPU is a microprocessor for image processing, and is connected to the display screen 194 and an application processor.

The display screen 194 is used to display images or videos, etc. A series of Graphical User Interfaces (GUIs) may be displayed on the display screen 194 of the User device 100.

The user device 100 may implement a photographing function through the ISP, the camera 193, the video codec, the GPU, the display screen 194, and the application processor, etc.

The camera 193 is used to capture still images or video.

The external memory interface 120 may be used to connect an external memory card, such as a Micro SD card, to enable expansion of the storage capability of the user device 100.

The internal memory 121 may be used to store computer-executable program code, which includes instructions. The processor 110 executes various functional applications of the user equipment 100 and data processing by executing instructions stored in the internal memory 121.

User equipment 100 may implement audio functions such as music playing, recording, etc. through audio module 170, speaker 170A, headphones 170B, microphone 170C, headset interface 170D, and an application processor, etc.

The SIM card interface 195 is used to connect a SIM card. The SIM card can be inserted into the SIM card interface 195 or extracted from the SIM card interface 195 to make contact with and separate from the user equipment 100. The user equipment 100 may support 1 or N SIM card interfaces, N being a positive integer greater than 1. The SIM card interface 195 may support a Nano SIM card, a Micro SIM card, a SIM card, etc. The same SIM card interface 195 can be inserted with multiple cards at the same time. The SIM card interface 195 may also be compatible with external memory cards. The user equipment 100 interacts with the network through the SIM card to implement functions such as a call and data communication.

On top of the above components, operating systems such as the iOS operating system, the android operating system, the windows operating system, etc. run. Applications may be installed and run on the operating system. In other embodiments, there may be multiple operating systems running within user device 100.

Fig. 4 is a flowchart of a network redirection method provided in an embodiment of the present application.

As shown in fig. 4, the method may include the steps of:

step S101, when the user equipment is redirected to the network, the user equipment searches a target cell on a target frequency point appointed by the network side.

The network redirection may be initiated by the network side when the ue and the network side are in a Radio Resource Control (RRC) connected state. For example: the network side may send an RRC connection release message (RRC connection release) or an RRC connection discard message (RRC connection reject) to the user equipment, and carry redirection information redirectedcarrierientinfo in the RCC connection release message or the RRC connection discard message to initiate network redirection. The redirection information may include, for example, a target frequency point specified by the network side to instruct the network side to search for a target cell on the target frequency point.

Illustratively, the network side initiating the network redirection to the user equipment includes, but is not limited to, occurring in the following scenarios:

exemplary scenario 1: when user equipment residing in an NR network initiates an IMS voice call, if a network side does not support VoNR, the user equipment needs to fall back to a 4G network to use an IMS voice service, and at the moment, the network side can initiate redirection to the user equipment, so that the user equipment is redirected from the NR network to an LTE network.

Exemplary scenario 2: when the user equipment resides in the NR cell, the network side detects that the signal quality of the user equipment is poor, initiates network redirection to the network side, and indicates a frequency point of an LTE cell, at this time, the user equipment can search the LTE cell on the frequency point indicated by the network side and redirect the LTE cell.

Exemplary scenario 3: when user equipment provided with network service by operator a moves to an area uncovered by the cell of operator a, if the area is covered by the cell of operator B and inter-network roaming is supported between operator a and operator B, the network side of operator a may initiate network redirection to the user equipment and indicate the frequency point where the cell of operator B is located. In this way, the user equipment may search for the cell of operator B on the frequency point indicated by the network side, and roam to the cell of operator B.

After receiving the redirection information, the user equipment may release the RRC connection established in the current cell, and perform cell search on the target frequency point. If the user equipment searches the cells on the target frequency point, the searched cells can be sequenced according to the signal quality of the cells, so that the target cells are determined. The target cell may be, for example, the cell with the best signal quality. The parameters for determining the cell signal quality may include, for example, a Received Signal Strength Indication (RSSI), a Reference Signal Receiving Power (RSRP), and the like.

Generally, to facilitate the user equipment to use the operator's network, the operator may embed its own PLMN identity in the SIM card it provides to the user equipment. After the user equipment inserts the SIM card, the PLMN identities may be read from the SIM card, and then the PLMN identity recorded in the SIM card is the PLMN identity known to the user equipment. In addition, the user equipment may also embed some known PLMN identities at the time of factory shipment.

After determining the target cell, the user equipment may determine whether the target cell belongs to an unidentified PLMN according to the PLMN identifier of the PLMN of the target cell. Specifically, if the PLMN identity of the PLMN of the target cell is different from the known PLMN identity of the user equipment, the user equipment may determine that the target cell belongs to an unidentified PLMN; if the PLMN identity of the PLMN of the target cell is the same as any PLMN identity known to the user equipment, the user equipment may determine that the target cell belongs to the identified PLMN.

Step S102, if the target cell belongs to the unidentified PLMN, the user equipment takes the target cell as the cell of the EPLMN and initiates network registration to the target cell.

According to the existing protocol, the network registration procedure of the user equipment may include, for example, an RRC connection establishment procedure, an Attach access procedure, and the like, and this embodiment of the present application is only described as an example.

For example: in the RRC connection establishment procedure, the ue may send an RRC connection request (RRC connection request) message to the network side. The network side may transmit an RRC connection setup (RRC connection setup) message to the user equipment if the RRC connection request of the user equipment is accepted. After the RRC connection is established, the ue may send an RRC connection setup complete (RRC connection setup complete) message to the network side. In addition, if the network side rejects the RRC connection request of the user equipment, an RRC connection reject (RRC connection reject) message may be transmitted to the user equipment. The user equipment may determine that the network registration has failed (registration rejected by the network) if it receives the RRC connection reject message. In addition, the user equipment may determine that the network registration has failed (the network does not respond) if it does not receive a message for network-side feedback within a period of time after transmitting the RRC connection request.

For another example, in the Attach access procedure, the ue may send an Attach request (Attach request) message to the network side. Thereafter, the network side may send an authentication request or the like to the user equipment to request the user equipment to send its own capability information or the like to the network side. Next, the network side may determine whether to allow network registration of the user equipment according to the information sent by the user equipment. If the network side allows the network registration of the user equipment, an Attach complete (Attach complete) message may be sent to the user equipment. If the network side rejects the network registration of the user equipment, the network side may send an Attach reject (Attach reject) message to the user equipment. The user equipment may determine that the network registration is successful if an Attach complete message is received, and may determine that the network registration is failed (registration is rejected by the network) if an Attach reject message is received. In addition, the user equipment may determine that network registration has failed (network unresponsive) if it does not receive a message for network-side feedback within a period of time after transmitting the Attach request.

It should be added that, in the existing protocol, when the user equipment is redirected to the network, if the searched target cell belongs to an unidentified PLMN, registration is not initiated to the target cell. In the embodiment of the present application, if the target cell searched by the ue belongs to an unidentified PLMN, the ue regards the unidentified PLMN as an EPLMN, that is, the unidentified PLMN is regarded as a known PLMN with the same priority as the RPLMN. In this way, the user equipment can also initiate network registration to the target cell without changing the existing protocol, thereby avoiding the problem that the user equipment returns to the RPLMN cell again due to redirection failure.

Step S103, when the network registration fails or succeeds but has abnormal service, the user equipment disables the PLMN of the target cell and/or disables the network system corresponding to the PLMN of the target cell.

It can be understood that, since the PLMN to which the target cell belongs is not the true RPLMN, after the user equipment initiates network registration with the target cell, there may be a case where the network registration fails or the network registration succeeds but the service is abnormal. The service exception includes, but is not limited to, that the user equipment cannot make a calling or called call, cannot use packet data, has a low data transmission rate, and is unstable in connection. In this case, the user equipment may disable the PLMN of the target cell and the network type of this PLMN. Here, the "network system" refers to a wireless communication system adopted by the PLMN, for example: 5G NR, LTE, WCDMA, TD-SCDMA, etc., and may further specifically include TD-LTE, FDD-LTE, etc., which are not specifically limited herein.

Therefore, the user equipment can not initiate network registration to the cell of the PLMN any more, thereby avoiding repeated problems of network registration failure or network registration success but service unavailability.

Fig. 5 is a more specific flowchart of a network redirection method provided in an embodiment of the present application.

As shown in fig. 5, in an implementation manner, the method may specifically include the following steps:

step S201, when the user equipment is redirected to the network, the user equipment searches a target cell on a target frequency point appointed by the network side.

The user equipment may search for the target cell on the target frequency point by referring to step S101, which is not described herein again.

Step S202, if the target cell is searched, the user equipment judges whether the target cell belongs to unidentified PLMN or not.

In a specific implementation, the user equipment may determine whether the target cell belongs to an unidentified PLMN according to the PLMN identifier of the PLMN of the target cell. Specifically, if the PLMN identity of the PLMN of the target cell is different from the known PLMN identity of the user equipment, the user equipment may determine that the target cell belongs to an unidentified PLMN; if the PLMN identity of the PLMN of the target cell is the same as any PLMN identity known to the user equipment, the user equipment may determine that the target cell belongs to the identified PLMN.

Step S203, if the target cell belongs to an unidentified PLMN, the user equipment determines whether the PLMN identifier of the PLMN of the target cell exists in a preset PLMN white list. If not, the user equipment performs step S204. If so, the user equipment performs step S211.

In specific implementation, the user equipment may record a PLMN white list established according to PLMN identifier plans (network number plans) of different countries and different operators, where the PLMN white list may also be referred to as a PLMN identifier white list, a network number white list, and the like, and is not limited specifically here.

Table 1 shows one achievable format for the PLMN white list.

Table 1 PLMN white list of user equipment

As shown in table 1, the PLMN white list may record the mobile device country codes MCC of each country and the white list PLMN identity (also called white list network number) corresponding to each MCC. For example: the MCC 460 shown in table 1 is a mobile device country code in china, and its corresponding whitelist PLMN identifiers 46000, 46001, etc. are PLMN identifiers of respective network operators in china. The PLMN identifier recorded in the PLMN white list may be an identifier of a PLMN compatible with the user equipment.

It should be added that, in the embodiment of the present application, the PLMN white list may be pre-written into the storage of the user equipment when the user equipment leaves a factory, or may be obtained by the user equipment from a server of an equipment manufacturer subsequently, and in addition, the user equipment may also update the PLMN white list from the server in a manner of actively obtaining or receiving push, which is not specifically limited in the embodiment of the present application.

In this way, after determining that the target cell belongs to the unidentified PLMN, the user equipment may search the PLMN white list according to the PLMN identifier of the PLMN of the target cell, so as to determine whether the PLMN identifier of the PLMN of the target cell exists in the PLMN white list. If yes, it indicates that the PLMN identifier of the PLMN of the target cell is not the new PLMN identifier, and then the user equipment performs step S210. If not, it indicates that the PLMN identifier of the PLMN of the target cell is the newly added PLMN identifier, and then the user equipment executes step S204.

Step S204, the user equipment judges whether other cells are searched on the target frequency point. If not, the user equipment performs step S205. If so, the user equipment performs step S210.

It can be understood that, when the user equipment performs cell search on the target frequency point, in addition to being able to search for the target cell, other cells may also be searched, but the signal quality of other cells may not be as good as that of the target cell, and therefore, the other cells are not selected as the target cell. When the user equipment also searches for other cells, if the target cell belongs to an unidentified PLMN, the user equipment may perform step S210 to select to initiate network registration in other cells without performing step S205.

Step S205, the user equipment takes the target cell as the cell of the EPLMN, and initiates network registration to the target cell.

The network registration initiated by the user equipment to the target cell may be implemented with reference to step S102, which is not described herein again.

In step S206, the ue determines whether the network registration is successful. If so, the user equipment performs step S207. If not, the user equipment performs step S208.

The step S102 may be performed by the user equipment to determine whether the network registration is successful, which is not described herein again.

For two scenarios, namely "registration rejected by network" and "network unresponsive" included in network registration failure, when the user equipment initiates registration to the network side, a registration timer may also be started to identify the two scenarios.

Fig. 6 is a flowchart illustrating a network registration failure according to an embodiment of the present application.

As shown in fig. 6, the network registration failure procedure may include the following steps:

step S301, the ue initiates network registration to the network side and starts a registration timer.

In a specific implementation, the ue may start a registration timer while sending the RRC connection request message to the target cell, where the registration timer is set to a preset duration and runs out of time after the preset duration. The duration of the registration timer may be, for example, 100ms, 200ms, and the like, which is not limited in this embodiment of the application.

Step S302, the network side sends down a registration rejection message to the user equipment.

In a specific implementation, the registration rejection message may be, for example, an RRC connection rejection message or an Attach rejection message issued by the network side. The user equipment declares "registration rejected by the network" if it receives a registration reject message before the registration timer expires.

Fig. 7 is another flowchart illustrating a network registration failure according to an embodiment of the present application.

As shown in fig. 7, the network registration failure procedure may include the following steps:

Step S303, if the registration timer is overtime, the ue still does not receive the feedback from the network.

In a specific implementation, if the registration timer has timed out, but the user equipment has not received a registration completion message delivered from the network side, for example, an attach complete message is not received, the "network does not respond".

Step S207, the user equipment determines whether there is a service anomaly. If so, go to step S208. If not, step S209 is performed.

In a specific implementation, the user equipment may continuously monitor the service performance on the unidentified PLMN for a period of time after the network registration is successful, so as to determine whether a service anomaly exists. The time period may be, for example, several seconds or several minutes, and the embodiment of the present application is not limited thereto. For example: if the user equipment can normally carry out calling or called conversation, can use packet data and has normal data transmission rate, the service is normal. If the user equipment can not carry out calling or called conversation, or can not use packet data, or the data transmission rate is low, the service abnormity is shown.

Step S208, the user equipment disables the PLMN of the target cell, and/or disables the network system corresponding to the PLMN of the target cell.

In a specific implementation, the user equipment may have different manners when performing step S208 according to whether the network redirection is a redirection between different systems. The redirection between heterogeneous systems herein refers to redirection between different wireless communication systems, for example, redirection from NR to LTE, redirection from LTE to WCDMA, and the like.

In one implementation, no matter whether the network redirection is between different systems, when the network registration fails or is successful but there is a service anomaly, the user equipment disables the PLMN of the target cell and disables the network standard corresponding to the PLMN of the target cell.

In another implementation, when the network registration fails or the network registration is successful but there is a service anomaly, if the network redirection is redirection between the same systems, the user equipment disables the PLMN of the target cell, if the network redirection is redirection between heterogeneous systems, the user equipment disables the PLMN of the target cell, and disables the network type corresponding to the PLMN of the target cell in the target cell.

Step S209, the ue camps on the target cell.

In specific implementation, if the user equipment has no service abnormality, the user equipment resides in the target cell, and the PLMN of the target cell is formally added as the EPLMN, and the EPLMN will continuously take effect in subsequent flows of network registration, network reselection, network redirection, and the like. In addition, the user equipment may display the operator name of this EPLMN as the operator name of the RPLMN in its status bar without displaying the roaming icon. Alternatively, the PLMN id (net number) of the EPLMN is directly displayed in the status bar without displaying the roaming icon.

Step S210, the user equipment ends the network redirection method according to the embodiment of the present application, and initiates network registration to the target cell or other searched cells according to a conventional registration procedure.

In a specific implementation, if the PLMN identifier of the PLMN of the target cell exists in the preset PLMN white list, it indicates that the PLMN identifier of the PLMN of the target cell is not the newly added PLMN identifier, and therefore the user equipment may directly initiate network registration to the target cell according to a conventional registration procedure.

In addition, if the user equipment searches other cells, the user equipment can directly initiate network registration to other cells according to a conventional registration flow, so that the problem that the user equipment returns to the RPLMN cell again due to redirection failure is avoided.

In order to facilitate those skilled in the art to further understand the technical solution of the embodiment of the present application, the following respectively describes flows executed by the network redirection method provided in the embodiment of the present application in two scenarios, i.e., successful network registration and normal service of the user equipment, and successful network registration and abnormal service of the user equipment. For specific implementation of each step in each flow described below, please refer to each step shown in fig. 5 to 7 of the embodiments of the present application, which is not described in detail below.

Fig. 8 is a flowchart of the network redirection method implemented in the present application when the network registration of the user equipment is successful and the service is normal.

As shown in fig. 8, the process includes:

step S401, the network side issues redirection to the user equipment to indicate the target frequency point.

Step S402, the user equipment searches a target cell on the target frequency point, the target cell belongs to an unidentified PLMN, and the PLMN identification of the PLMN of the target cell is not in a PLMN white list.

Step S403, the ue regards the unidentified PLMN as an EPLMN, initiates network registration to the target cell, and starts a registration timer.

Step S404, before the register timer is overtime, the network side sends register completion information to the user equipment.

Step S405, the ue continuously monitors the service performance on the unidentified PLMN for a period of time, and finds that the service of the ue is normal.

In step S406, the ue formally adds the unidentified PLMN as the EPLMN and continues to take effect in the subsequent flow.

In step S407, the ue displays the operator name of the EPLMN as the operator name of the RPLMN without displaying the roaming icon. Alternatively, the PLMN identity of the EPLMN is displayed directly in the status bar without displaying the roaming icon.

Fig. 9 is a flowchart of a network redirection method according to an embodiment of the present application when network registration of a user equipment is successful but a service is abnormal.

As shown in fig. 9, the process includes:

step S501, the network side issues redirection to the user equipment to indicate a target frequency point.

Step S502, the user equipment searches a target cell on the target frequency point, the target cell belongs to the unidentified PLMN, and the PLMN identification of the PLMN of the target cell is not in the PLMN white list.

Step S503, the UE regards the unidentified PLMN as the EPLMN, initiates network registration to the target cell, and starts a registration timer.

Step S504, before the register timer is overtime, the network side sends register completion information to the user equipment.

Step S505, the ue continuously monitors the service performance on the unidentified PLMN for a period of time, and finds that the service of the ue is abnormal.

Step S506, the ue disables the unidentified PLMN and disables the network type of the unidentified PLMN.

Step S507, the ue re-initiates cell search and network registration procedures.

In the embodiments provided in the present application, the aspects of the network redirection method provided in the present application are introduced from the perspective of the user equipment itself and the interaction between the user equipment and the network side. It will be appreciated that the user equipment, in order to implement the above-described functions, comprises corresponding hardware structures and/or software modules for performing the respective functions. Those of skill in the art would readily appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as hardware or combinations of hardware and computer software. Whether a function is performed as hardware or computer software drives hardware depends upon the particular application and design constraints imposed on the solution. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present application.

Fig. 10 is a schematic structural diagram of a network redirection device according to an embodiment of the present application.

In some embodiments, the UE may implement the corresponding functions by the hardware apparatus shown in fig. 10. As shown in fig. 10, the network redirection device may include: a transceiver 601, a memory 602, and a processor 603.

In one implementation, the processor 603 may include one or more processing units, such as: the processor 603 may include an applications processor, a modem processor, a graphics processor, an image signal processor, a controller, a video codec, a digital signal processor, a baseband processor, and/or a neural network processor, among others. Wherein, the different processing units may be independent devices or may be integrated in one or more processors. The memory 602 is coupled to the processor 603 for storing various software programs and/or sets of instructions. In some embodiments, memory 602 may include volatile memory and/or non-volatile memory. The transceiver 601 may include, for example, a radio frequency circuit, a mobile communication module, a wireless communication module, and the like, and is used for implementing a wireless communication function of the UE.

In one embodiment, the software program and/or sets of instructions in the memory 602, when executed by the processor 603, cause the user equipment to perform the method steps of: when the network is redirected, searching a target cell on a target frequency point appointed by a network side; and if the PLMN of the target cell is the unidentified PLMN, taking the target cell as the cell of the EPLMN, and initiating network registration to the target cell.

According to the technical scheme, when the user equipment redirects the network, if the searched target cell belongs to the unidentified PLMN, the target cell is used as the cell of the RPLMN to initiate network registration, so that the problem of network redirection failure caused by the fact that the user equipment cannot initiate network registration to the unidentified PLMN in the prior art is solved.

Optionally, the software program and/or sets of instructions in the memory 602, when executed by the processor 603, further cause the user equipment to perform the method steps of: judging whether the network registration is successful; if the network registration is successful, judging whether the service abnormality exists in the preset duration after the network registration is successful; and if the service is abnormal, forbidding the PLMN of the target cell and/or forbidding the network system corresponding to the PLMN of the target cell. In this way, the user equipment will not initiate network registration with the cell of the PLMN thereafter, thereby avoiding the problem of network registration success but service unavailability from recurring.

Optionally, the software program and/or sets of instructions in the memory 602, when executed by the processor 603, further cause the user equipment to perform the method steps of: and if the network registration fails, forbidding the PLMN of the target cell and/or forbidding the network system corresponding to the PLMN of the target cell. Therefore, the user equipment does not initiate network registration to the cell of the PLMN any more, and repeated network registration failure is avoided.

Optionally, the software program and/or sets of instructions in the memory 602, when executed by the processor 603, further cause the user equipment to perform the method steps of: if no abnormal service exists, residing in the target cell and determining the PLMN of the target cell as the EPLMN. Thus, if the user equipment searches the target cell again in the later network redirection, the network registration can be directly initiated to the target cell according to the existing protocol.

Optionally, when the software program and/or the plurality of sets of instructions in the memory 602 are executed by the processor 603, the user equipment is specifically configured to perform the following method steps: judging whether the PLMN identification of the PLMN of the target cell exists in a preset PLMN white list, wherein the PLMN white list comprises the PLMN identifications of a plurality of PLMNs; if the PLMN identification of the PLMN of the target cell exists in the PLMN white list, judging whether other cells are searched on the target frequency point; and if other cells are not searched on the target frequency point, taking the target cell as the EPLMN cell, and initiating network registration to the target cell. Therefore, the user equipment can judge whether the PLMN of the target cell is the newly added PLMN according to the PLMN white list, and initiate network registration to the target cell when determining whether the PLMN of the target cell is the newly added PLMN and other cells are not searched on the target frequency point.

Optionally, the software program and/or sets of instructions in the memory 602, when executed by the processor 603, further cause the user equipment to perform the method steps of: and if the service abnormity does not exist, displaying the operator name of the PLMN of the target cell as the operator name of the Registered Public Land Mobile Network (RPLMN).

Optionally, when the software program and/or the plurality of sets of instructions in the memory 602 are executed by the processor 603, the user equipment is specifically configured to perform the following method steps: if the network redirection is the redirection between the same systems, the PLMN of the target cell is forbidden; and if the network redirection is the redirection between different systems, forbidding the PLMN of the target cell, and forbidding the network system corresponding to the PLMN of the target cell under the target cell. Therefore, when the network redirection is the redirection between the same systems, the user equipment cannot redirect to the unidentified PLMN again, and when the network redirection is the redirection between the same systems, the user equipment cannot redirect to the new network standard corresponding to the unidentified PLMN again, so that the problem that the network fails to orient again is avoided.

Optionally, the software program and/or sets of instructions in the memory 602, when executed by the processor 603, further cause the user equipment to perform the method steps of: starting a registration timer when initiating network registration to a target cell; if receiving the registration completion message of the network side, determining that the network registration is successful; if a registration reject message of the network side is received, or if the registration timer has timed out but a registration completion message of the network side is not received, determining that the network registration fails.

In some embodiments, the UE may implement the respective functions through a software module. As shown in fig. 11, the network redirection device for implementing the function of the user equipment includes: search section 701 and registration section 702.

Wherein: a searching unit 701, configured to search a target cell on a target frequency point specified by a network side when the network is redirected; a registering unit 702, configured to, if the PLMN of the target cell is an unidentified PLMN, use the target cell as a cell of the EPLMN, and initiate network registration to the target cell.

Optionally, the apparatus further comprises: a first determining unit 703, configured to determine whether network registration is successful; a second determining unit 704, configured to determine whether a service exception exists within a preset time period after the network registration is successful if the network registration is successful; an executing unit 705, configured to disable a PLMN of the target cell and/or disable a network type corresponding to the PLMN of the target cell if the service is abnormal. In this way, the user equipment will not initiate network registration with the cell of the PLMN thereafter, thereby avoiding the problem of network registration success but service unavailability from recurring.

Optionally, the executing unit 705 is further configured to disable the PLMN of the target cell and/or disable the network type corresponding to the PLMN of the target cell if the network registration fails. Therefore, the user equipment does not initiate network registration to the cell of the PLMN any more, thereby avoiding repeated network registration failure.

Optionally, the executing unit 705 is further configured to camp on the target cell if there is no traffic anomaly, and determine the PLMN of the target cell as the EPLMN. Thus, if the user equipment searches the target cell again in the later network redirection, the network registration can be directly initiated to the target cell according to the existing protocol.

Optionally, the apparatus further comprises: a third determining unit 706, configured to determine whether a PLMN identifier of a PLMN of the target cell exists in a preset PLMN white list, where the PLMN white list includes PLMN identifiers of multiple PLMNs; a fourth determining unit 707, configured to determine whether other cells are searched on the target frequency point if the PLMN identifier of the PLMN of the target cell exists in the PLMN white list; the registering unit 703 is specifically configured to, if no other cell is searched on the target frequency point, use the target cell as the cell of the EPLMN, and initiate network registration to the target cell. Therefore, the user equipment can judge whether the PLMN of the target cell is the newly added PLMN according to the PLMN white list, and initiate network registration to the target cell when the PLMN of the target cell is determined to be the newly added PLMN and other cells are not searched on the target frequency point.

Optionally, the executing unit 705 is further configured to display the operator name of the PLMN of the target cell as the operator name of the registered public land mobile network RPLMN if there is no service anomaly.

Optionally, the executing unit 705 is configured to disable the PLMN of the target cell, and/or disable the network system corresponding to the PLMN of the target cell, and specifically includes: if the network redirection is the redirection between the same systems, the user equipment disables the PLMN of the target cell; if the network redirection is the redirection between different systems, the user equipment disables the PLMN of the target cell, and disables the network system corresponding to the PLMN of the target cell under the target cell. Therefore, when the network redirection is the redirection between the same systems, the user equipment cannot redirect to the unidentified PLMN again, and when the network redirection is the redirection between the same systems, the user equipment cannot redirect to the new network standard corresponding to the unidentified PLMN again, so that the problem that the network fails to orient again is avoided.

Optionally, the first determining unit 703 is specifically configured to: when user equipment initiates network registration to a target cell, starting a registration timer; if the user equipment receives a registration completion message of a network side, determining that the network registration is successful; if the user equipment receives the registration rejection message of the network side, or if the registration timer has timed out but the user equipment does not receive the registration completion message of the network side, the network registration is determined to be failed.

Embodiments of the present application also provide a computer storage medium, in which program instructions are stored, and when the program instructions are executed on a computer, the computer is enabled to execute the methods in the above aspects and the various implementation manners.

Embodiments of the present application also provide a computer program product, which when run on a computer, causes the computer to perform the methods in the above aspects and their various implementations.

The application also provides a chip system. The system on chip comprises a processor for enabling the above apparatus or device to perform the functions recited in the above aspects, for example, generating or processing information recited in the above methods. In one possible design, the system-on-chip further includes a memory for storing program instructions and data necessary for the above-described apparatus or device. The chip system may be constituted by a chip, or may include a chip and other discrete devices.

The above embodiments are only for illustrating the embodiments of the present invention and are not to be construed as limiting the scope of the present invention, and any modifications, equivalent substitutions, improvements and the like made on the basis of the embodiments of the present invention shall be included in the scope of the present invention.

Claims

1. A method for network redirection, comprising:

when the user equipment is redirected to the network, searching a target cell on a target frequency point appointed by the network side;

if the Public Land Mobile Network (PLMN) of the target cell is an unidentified PLMN, the user equipment judges whether the PLMN identification of the PLMN of the target cell exists in a preset PLMN white list, wherein the PLMN white list comprises the PLMN identifications of a plurality of PLMNs;

if the PLMN identification of the PLMN of the target cell exists in the PLMN white list, the user equipment judges whether other cells are searched on the target frequency point;

if no other cell is searched on the target frequency point, the user equipment takes the target cell as the cell of the EPLMN and initiates network registration to the target cell;

wherein the unidentified PLMN is a PLMN whose PLMN identification is not identified by the user equipment.

2. The method of claim 1, wherein after the ue initiates network registration with the target cell, the method further comprises:

the user equipment judges whether the network registration is successful;

if the network registration is successful, the user equipment judges whether the service abnormality exists in the preset time after the network registration is successful;

and if the service is abnormal, the user equipment forbids the PLMN of the target cell and/or forbids a network system corresponding to the PLMN of the target cell.

3. The method of claim 2, further comprising:

and if the network registration fails, the user equipment disables the PLMN of the target cell and/or disables the network system corresponding to the PLMN of the target cell.

4. The method of claim 2 or 3, further comprising:

and if the service abnormity does not exist, the user equipment is resided in the target cell, and the PLMN of the target cell is determined as the EPLMN.

5. The method of claim 1, further comprising:

and if the service abnormity does not exist, the user equipment displays the operator name of the PLMN of the target cell as the operator name of the Registered Public Land Mobile Network (RPLMN).

6. The method according to claim 2 or 3, wherein the step of disabling, by the user equipment, the PLMN of the target cell and/or disabling a network standard corresponding to the PLMN of the target cell comprises:

if the network redirection is the redirection between the same systems, the user equipment disables the PLMN of the target cell;

if the network redirection is the redirection between different systems, the user equipment disables the PLMN of the target cell, and disables the network standard corresponding to the PLMN of the target cell under the target cell.

7. The method of claim 1, further comprising:

when the user equipment initiates network registration to the target cell, starting a registration timer;

if the user equipment receives a registration completion message of a network side, the user equipment determines that network registration is successful;

if the user equipment receives a registration rejection message of the network side, or if the registration timer has already timed out but the user equipment does not receive a registration completion message of the network side, the user equipment determines that the network registration fails.

8. A network redirection device, comprising:

the searching unit is used for searching a target cell on a target frequency point appointed by a network side when the network is redirected;

a registration unit, configured to determine whether a PLMN identifier of a PLMN of the target cell exists in a preset PLMN white list if the PLMN of the target cell is an unidentified PLMN, where the PLMN white list includes PLMN identifiers of multiple PLMNs; if the PLMN identification of the PLMN of the target cell exists in the PLMN white list, judging whether other cells are searched on the target frequency point; if no other cell is searched on the target frequency point, taking the target cell as the cell of the EPLMN, and initiating network registration to the target cell;

wherein the unidentified PLMN is a PLMN whose PLMN identification is not identified by the network redirection device.

9. A user device, comprising: a processor and a memory; the memory stores program instructions that, when executed by the processor, cause the user equipment to perform the method of any of claims 1-7.

10. A chip system, comprising: a memory and a processor; the memory stores program instructions that, when executed by the processor, cause the system-on-chip to perform the method of any of claims 1-7.

11. A computer storage medium, characterized in that a computer readable storage medium has stored therein program instructions, which when run on a computer, cause the computer to perform the method of any one of claims 1-7.