CN110677890B

CN110677890B - Multi-card multi-4G mobile terminal and network reselection method thereof

Info

Publication number: CN110677890B
Application number: CN201911216055.5A
Authority: CN
Inventors: 刘科; 田建军
Original assignee: Marvell World Trade Ltd
Current assignee: ASR Microelectronics Co Ltd
Priority date: 2019-12-03
Filing date: 2019-12-03
Publication date: 2020-04-10
Anticipated expiration: 2039-12-03
Also published as: CN110677890A

Abstract

The application discloses a method for reselecting a network by a multi-card multi-4G mobile terminal, which comprises the following steps. And establishing a shared memory area which can be accessed by all the SIM cards. When the SIM card is in the 2G or 3G operating mode, at the time when the inter-system measurement needs to be started, the inter-system measurement in the 2G or 3G mode is not started, but the information of the rest SIM cards is read from the shared memory area. And if the SIM card II in the shared memory area meets the specific condition, the SIM card I does not start inter-system measurement, the SIM card I directly reads the 4G cell where the SIM card II currently resides from the shared memory area, and the cell is used as a target cell for 4G reselection of the SIM card I, and initiates a residence process to the target cell. Otherwise, the SIM card starts the inter-system measurement in the 2G or 3G mode as soon as the SIM card resumes. The method and the device can enable the SIM card in the 2G or 3G mode to quickly reselect back to the 4G mode under specific conditions.

Description

Multi-card multi-4G mobile terminal and network reselection method thereof

Technical Field

The application relates to a method for quickly reselecting a SIM card from a 2G or 3G mobile communication network to a 4G mobile communication network in a multi-card multi-4G mobile terminal.

Background

The development of Mobile communication technology starts from the first generation of analog cellular Mobile communication systems, to the second generation of Global System for Mobile communication (GSM) which provides voice service and low-rate data service under good network coverage conditions, to the third generation of Universal Mobile Telecommunications System (UMTS) which further provides more types of broadband multimedia services, and the introduction of LTE (Long Term Evolution) brings the Mobile communication technology into the 4G era.

A 4G mobile terminal (UE) supporting GSM, UMTS, and LTE has been widely used. In order to reasonably utilize the mobile communication network resources, mobile communication operators can adopt various different network switching strategies, so that mobile terminals can be flexibly switched on different mobile communication networks, and users can be guaranteed to always enjoy the optimal network service. Since the 4G network has higher data transmission rate and unique Voice over LTE (Voice over LTE) Voice service, "4G first" is a standard network selection configuration in most 4G mobile terminals.

For convenience of description, in this document, a Subscriber Identity Module (SIM) card is used to denote a smart card used by a mobile terminal, in which subscriber identity data, an authentication algorithm, a corresponding key, and the like are stored for identifying and authenticating the mobile terminal accessing a mobile communication network. The SIM Card is to be understood in a broad sense, and includes R-uim (removable User Identity module) Card, uim (User Identity module) Card, UICC (Universal Integrated Circuit Card) built-in SIM application, usim (Universal electronic subscriber Identity module) application, csim (cdma Identity module) and the like having the same function in different mobile communication networks.

The multi-card multi-4G mobile terminal means that the mobile terminal is provided with a plurality of SIM cards, each SIM card is a 4G multi-mode SIM card, and the mobile terminal can simultaneously work in a 4G mode. The 4G multi-mode SIM card can automatically select to reside in a 2G, 3G or 4G mobile communication network according to the network environment, for example, corresponding to a GSM, UTMS or LTE network respectively. The user can arbitrarily select one SIM card as a main card for bearing data service; the rest SIM cards are used as auxiliary cards, but can still use services such as VoLTE high-definition voice, video and the like.

In the existing multi-card multi-4G mobile terminal, the data service of the main card is nearly in a always connected state, and the frequent uplink and downlink data transmission on the main card occupies more resources of a physical layer and a radio frequency module of the mobile terminal, so that the situation that the inter-system cell measurement and reselection cannot be completed in time due to insufficient resources sometimes occurs in the auxiliary card. In use, once the secondary card is switched into the 2G or 3G mobile communication network, the secondary card cannot reselect the 4G mobile communication network for a long time, so that the 4G service on the secondary card cannot be performed, and the actual application and implementation of the network switching policy of the mobile communication operator are also affected.

Disclosure of Invention

The technical problem to be solved by the present application is to provide a method for reselecting a network for a multi-card multi-4G mobile terminal, which can enable a SIM card in a 2G or 3G mode to quickly reselect back to a 4G mode under a specific condition. Therefore, the application also provides a corresponding multi-card multi-4G mobile terminal.

In order to solve the above technical problem, the present application provides a method for reselecting a network for a multi-card multi-4G mobile terminal, which includes the following steps. Step S110: establishing a shared memory area which can be accessed by all SIM cards; and the software module belonging to any SIM card is allowed to access the shared memory area in the working process, and the mobile communication operator, the working mode, the service state and the current resident cell of each SIM card are stored in the shared memory area in real time. Step S120: when the first SIM card is in the 2G or 3G operating mode, at the time when the inter-system measurement needs to be started, the first SIM card does not start the inter-system measurement in the 2G or 3G mode, but reads the information of the mobile communication operator, the operating mode, and the service state of the other SIM cards from the shared memory area. Step S130: if the second SIM card and the first SIM card belong to the same mobile communication operator, the second SIM card is in the 4G mode, and the current service status of the second SIM card is normal service, the first SIM card does not start inter-system measurement, and step S150 is entered. Step S140: and if the SIM cards meeting the three conditions simultaneously do not exist in the shared memory area, the SIM card starts the inter-system measurement in the 2G or 3G mode once recovering. Step S150: and the SIM card I directly reads the 4G cell where the SIM card II currently resides from the shared memory area, and takes the cell as a target cell for 4G reselection of the SIM card I, and initiates the resident process from the target cell to the 4G mobile communication network.

According to the method for reselecting the network by the multi-card multi-4G mobile terminal, the SIM card in the 2G or 3G mode can be quickly reselected back to the 4G mode under a specific condition.

Further, in step S110, the shared memory area has a read-write operation protection mechanism, so as to avoid data collision when multiple SIM cards are read and written simultaneously. This is a preferred implementation.

Further, the read-write operation protection mechanism uses a static global variable to define a special data structure as the shared memory area, wherein the data is managed in a member variable mode; each time of reading and writing operation only aims at a certain specific member variable, through a task priority mechanism provided in the real-time multi-task operating system, a certain software module task occupies the shared memory area, and when a certain member variable is read and written in the shared memory area, the other software modules cannot rewrite the member variable at the same time, so that access conflict of data in the shared memory area can be avoided. This is a preferred implementation in more detail.

Further, in step S120, the time when the inter-system measurement needs to be started refers to when the first SIM card is in the 2G or 3G operating mode, if there is another SIM card initiating a service with a higher priority, the scheduling mechanism interrupts the action of the first SIM card, the first SIM card enters the suspended state, and the bottom layer resource is allocated to the SIM card initiating the service with the higher priority for use; and when the high-priority service of the SIM card initiating the higher-priority service is finished, the scheduling mechanism can restore the running state of the 2G or 3G mode of the SIM card I, and after the 2G or 3G module of the SIM card I obtains the bottom layer resource and restores running, the inter-system measurement in the 2G or 3G mode is not started for a while. This is an exemplary detailed description of the "opportunity to initiate inter-system measurements".

Further, in step S130, the 2G or 3G module of the first SIM card no longer starts inter-system measurement, and directly sends a reselection request instruction to the inter-system reselection control module of the first SIM card, so as to request to directly use the currently camped 4G cell information of the second SIM card to reselect to the 4G mobile communication network, and then the 2G or 3G module of the first SIM card enters an inactive state from an active state.

Further, in step S150, after the inter-system reselection control module of the first SIM card receives the reselection request command sent by the 2G or 3G module of the first SIM card and requests to reselect the 4G mobile communication network by directly using the information of the currently camped 4G cell of the second SIM card, the inter-system cell reselection (inter cell reselection from GERAN/UTRAN to E-UTRAN) activation command is sent to the 4G module of the first SIM card, and the currently camped 4G cell of the second SIM card is designated as the reselection target cell; after receiving the instruction, the 4G module of the SIM card I enters an activated state from an inactivated state; the 4G module of the SIM card I acquires the information of the 4G cell currently resident by the 4G module of the SIM card II through a shared memory area, takes the information as a target cell reselected by the 4G and resides in the 4G target cell; and after the residence is successful, the 4G module of the SIM card I replies a signal of successful reselection of intersystem cell reselection from GERAN or UTRAN to E-UTRAN to the intersystem reselection control module of the SIM card I. Wherein, GERAN represents GSM/EDGE Radio access Network (GSM EDGE Radio access Network), UTRAN represents UMTS Terrestrial Radio access Network (UMTS Terrestrial Radio access Network), E-UTRAN represents Evolved UMTS Terrestrial Radio access Network (Evolved-UMTS Terrestrial Radio access Network). This is a preferred implementation.

Further, in step S150, if the SIM card fails to camp in the target cell, the SIM card reselects to the 2G or 3G mobile communication network, that is, the SIM card is still in the 2G or 3G operating mode, and the process returns to step S120. This is a preferred implementation.

The application also provides a multi-card multi-4G mobile terminal which comprises a shared storage unit, a first judging unit, a second judging unit, a first SIM card executing unit and a second SIM card executing unit. The shared memory unit is used for establishing a shared memory area which can be accessed by all the SIM cards. The first judging unit is used for judging whether any SIM card is in a 2G or 3G working mode and needs to start inter-system measurement; if so, the SIM card is called a SIM card one. The second judging unit is used for judging whether an SIM card in the shared memory area simultaneously meets three conditions, namely the SIM card and the SIM card belong to the same mobile communication operator, the SIM card works in a 4G mode, and the current service state of the SIM card is normal service; if so, the SIM card is called a second SIM card. The SIM card executing unit is used for storing a mobile communication operator, a working mode, a service state and a current resident cell in a shared memory area in real time; the SIM card executing unit is also used for temporarily not starting the inter-system measurement in the 2G or 3G mode when the first judging unit finds the SIM card meeting the requirement, but reading the information of the mobile communication operator, the working mode and the service state of the other SIM cards from the shared memory area; the first SIM card execution unit is further used for enabling the first SIM card not to start inter-system measurement when the second judgment unit finds the second SIM card meeting the requirement, requiring the first SIM card to directly read the currently resident 4G cell of the second SIM card from the shared memory area, and serving as a target cell for 4G reselection of the first SIM card, and initiating reselection of a resident process to the target cell to the 4G mobile communication network; the first SIM card executing unit is further configured to resume the first SIM card to start the inter-system measurement in the 2G or 3G mode when the second determining unit does not find the SIM card and satisfies the three conditions. The SIM card two execution units are used for storing a mobile communication operator, a working mode, a service state and a current resident cell in a shared memory area in real time.

The multi-card multi-4G mobile terminal can enable the SIM card in the 2G or 3G mode to quickly reselect back to the 4G mode under a specific condition.

Further, the SIM card executing unit is further configured to reselect the SIM card to the 2G or 3G mobile communication network when the SIM card fails to camp in the target cell, that is, the SIM card is still in the 2G or 3G operating mode. This is a preferred implementation.

Further, the shared memory unit is realized by a processor of the mobile terminal, a memory management subsystem in an operating system and a thread scheduling subsystem. The first judging unit is realized by a processor of the mobile terminal and a 2G module and/or a 3G module of each SIM card. The second judging unit is realized by a processor of the mobile terminal and a 2G module and/or a 3G module of each SIM card. The SIM card one execution unit is realized by a 2G module, a 3G module, an intersystem reselection control module and a 4G module of the SIM card one in the mobile terminal. The second SIM card execution unit is realized by a 2G module, a 3G module and a 4G module of a second SIM card in the mobile terminal. This is a preferred implementation.

The technical effect achieved by the application is that the SIM card in the 2G or 3G mode can be quickly reselected back to the 4G mode under specific conditions.

Drawings

Fig. 1 is a flowchart of a method for reselecting a network by a multi-card multi-4G mobile terminal provided by the present application.

Fig. 2 is a schematic structural diagram of a multi-card multi-4G mobile terminal provided by the present application.

The reference numbers in the figures illustrate: 200 is a multi-card multi-4G mobile terminal; 210 is a shared memory unit; 220 is a first judgment unit; 230 is a second judgment unit; 240 is an execution unit of the SIM card; and 250 is a SIM card two execution unit.

Detailed Description

In this application, the multi-card multi-4G mobile terminal means that the mobile terminal has more than two SIM cards, each SIM card is a 4G multi-mode SIM card, and can simultaneously operate in a 4G mode. The user can arbitrarily select one SIM card as a main card for bearing data service; the rest SIM cards are used as auxiliary cards, but can still use services such as VoLTE high-definition voice, video and the like. All SIM cards share a set of physical layer and radio frequency resource module, the occupation of bottom layer resources by each SIM card is managed by a scheduling mechanism based on service priority, when one SIM card initiates a high-priority service, the scheduling mechanism can interrupt the operation of low-priority services of other SIM cards, thereby ensuring that the SIM card where the high-priority service is located preferentially obtains the use right of the bottom layer resources, at the moment, the other SIM cards can enter a hang-up state, suspend certain actions needing to use the bottom layer resources, and wait for the recovery of the scheduling mechanism.

Referring to fig. 1, the method for reselecting a network for a multi-card multi-4G mobile terminal provided by the present application includes the following steps.

Step S110: and establishing a shared memory area which can be accessed by all the SIM cards. The software module belonging to any SIM card can access the shared memory area in the working process, and stores the information of mobile communication operators, working modes, service states, current resident cells and the like of each SIM card in real time.

Step S120: when any SIM card (for example, referred to as SIM card one) is in the 2G or 3G operating mode, at a time when the inter-system measurement needs to be started, the SIM card does not start the inter-system measurement in the 2G or 3G mode for the moment, but reads the information of the mobile communication operator, the operating mode, and the service state of the other SIM cards from the shared memory area.

Step S130: if one SIM card (for example, called as a second SIM card) and the first SIM card belong to the same mobile communication operator in the shared memory area, and the second SIM card operates in the 4G mode, and the current service state of the second SIM card is normal service (normal service), the 2G or 3G module of the first SIM card does not start inter-system measurement any more, but directly sends a specific reselection request (reselection request) instruction to the inter-system reselection control module of the first SIM card, so as to request to directly use the information of the currently residing 4G cell of the second SIM card to reselect the 4G mobile communication network. At this time, the SIM card can use the information provided by the SIM card two to speed up the reselection from the 2G or 3G mobile communication network back to the 4G mobile communication network. The process proceeds to step S150.

Step S140: if the shared memory area does not have the SIM card meeting the three conditions at the same time, the SIM card starts the inter-system measurement in the 2G or 3G mode once recovering.

Step S150: and when the 4G module of the first SIM card receives an activation instruction of the intersystem reselection control module of the first SIM card and designates the 4G cell where the second SIM card currently resides as a reselection target cell, the 4G module of the first SIM card is activated, directly reads the 4G cell where the second SIM card currently resides from the shared memory area and serves as the target cell where the first SIM card performs 4G reselection, and initiates a resident process to the target cell to reselect to the 4G mobile communication network.

Preferably, in step S110, the shared memory area has a read-write operation protection mechanism, so as to avoid data collision when multiple SIM cards are read and written simultaneously. The read-write operation protection mechanism, for example, uses a static global variable to define a dedicated data structure as the shared memory area, where data is managed in a member variable manner. Each time of reading and writing operation only aims at a certain specific member variable, through a task priority mechanism provided in the real-time multi-task operating system, a certain software module task occupies the shared memory area, and when a certain member variable is read and written in the shared memory area, the other software modules cannot rewrite the member variable at the same time, so that access conflict of data in the shared memory area can be avoided.

Preferably, in step S120, the time when the inter-system measurement needs to be started is, for example, when the first SIM card is in the 2G or 3G operating mode, if there is another SIM card (for example, referred to as the second SIM card) initiating a service with a higher priority, the scheduling mechanism interrupts an action of the first SIM card, the first SIM card enters the suspended state, and the underlying resource is allocated to the second SIM card for use. And when the high-priority service of the SIM card II is finished, the scheduling mechanism can restore the running state of the 2G or 3G mode of the SIM card I, and after the 2G or 3G module of the SIM card I obtains the bottom layer resource and restores running, the inter-system measurement in the 2G or 3G mode is not started for a while.

Preferably, in step S130, the 2G or 3G module of the first SIM card sends a specific reselection request instruction to the inter-system reselection control module of the first SIM card, and requests to directly use the currently camped 4G cell information of the second SIM card to reselect to the 4G mobile communication network, and then the 2G or 3G module of the first SIM card enters the inactive state from the active state.

Preferably, in the step S150, after the inter-system reselection control module of the first SIM card receives the reselection request command sent by the 2G or 3G module of the first SIM card and requests to reselect the 4G mobile communication network by directly using the information of the currently camped 4G cell of the second SIM card, the inter-system cell reselection from GERAN/UTRAN to E-UTRAN (inter-system cell reselection from GERAN or UTRAN to E-UTRAN) activation command is sent to the 4G module of the first SIM card, and the currently camped 4G cell of the second SIM card is designated as the reselection target cell. And after receiving the instruction, the 4G module of the SIM card I enters an activated state from an inactivated state. And the 4G module of the SIM card I acquires the information of the 4G cell currently resided by the 4G module of the SIM card II through the shared memory area, and the information is used as a target cell reselected by the 4G and resided in the 4G target cell. After the successful residence, the 4G module of the first SIM card replies a signal of successful reselection of the inter-system cell reselection from GERAN/UTRAN to E-UTRAN to the inter-system reselection control module of the first SIM card. Therefore, the SIM card is successfully reselected from the 2G or 3G mobile communication network to the 4G mobile communication network.

Preferably, in step S150, if the SIM card fails to camp on the target cell, the SIM card reselects to the 2G or 3G mobile communication network, that is, the SIM card is still in the 2G or 3G operating mode, and returns to step S120.

The application considers that when one SIM card (supposed to be a second SIM card) in the multi-card multi-4G mobile terminal works in a 4G mode and the other SIM card (supposed to be a first SIM card) works in a 2G or 3G mode, if 4G data traffic on the second SIM card is busy and uplink and downlink data are continuously transmitted, a physical layer and a radio frequency module of the mobile terminal are frequently occupied by the second SIM card, the frequent hang of the first SIM card by a multi-card scheduling mechanism can be caused, and inter-system measurement in the 2G or 3G mode can not be completed in time, so that a 4G mobile communication network can not be reselected for a long time. When the second SIM card and the first SIM card belong to the same mobile communication operator, the first SIM card can acquire the current information of the second SIM card through a shared memory area, and under the condition of meeting the conditions, the first SIM card can avoid the inter-system measurement and reselection evaluation process in a 2G or 3G mode, directly reside on a 4G cell where the second SIM card is located, and quickly reselect from the 2G or 3G mobile communication network to the 4G mobile communication network, so that the reselection network flow of the multi-card multi-4G mobile terminal is improved.

Referring to fig. 2, the present application also provides a multi-card multi-4G mobile terminal corresponding to the method for reselecting a network for a multi-card multi-4G mobile terminal. The multi-card multi-4G mobile terminal 200 includes a shared storage unit 210, a first determining unit 220, a second determining unit 230, a first SIM card executing unit 240, and a second SIM card executing unit 250.

The shared memory unit 210 is used to establish a shared memory area accessible by all SIM cards. The shared memory unit 210 is implemented by, for example, a processor of the mobile terminal, a memory management subsystem in an operating system, and a thread scheduling subsystem.

The first determining unit 220 is used to determine whether any SIM card is in the 2G or 3G operating mode and needs to initiate inter-system measurement. If so, the SIM card is referred to as SIM card one, for example. The first determining unit 220 is implemented by, for example, a processor of the mobile terminal and a 2G module and/or a 3G module of each SIM card.

The second determining unit 230 is configured to determine whether a SIM card and a SIM card in the shared memory area belong to the same mobile communication operator, the SIM card operates in the 4G mode, and the current service status of the SIM card is normal service. If so, the SIM card is called as a second SIM card, for example. The second determination unit 230 is implemented by, for example, a processor of the mobile terminal and a 2G module and/or a 3G module of each SIM card.

The SIM card-executing unit 240 is used for storing information of a mobile communication operator, a working mode, a service state, a current resident cell, and the like in real time in the shared memory area. The first SIM card executing unit 240 is further configured to, when the first determining unit 220 finds that the first SIM card meets the two conditions, read information of the mobile communication operator, the working mode, and the service state of the other SIM cards from the shared memory area without starting the inter-system measurement in the 2G or 3G mode. The first SIM card executing unit 240 is further configured to, when the second determining unit 230 finds that the second SIM card meets the three conditions at the same time, make the first SIM card no longer start inter-system measurement, make the first SIM card directly read the currently camped 4G cell of the second SIM card from the shared memory area by sending a specific reselection request instruction, and use the read cell as a target cell for performing 4G reselection on the first SIM card, and initiate a camping process to the target cell. The first SIM card executing unit 240 is further configured to resume the first SIM card to start the inter-system measurement in the 2G or 3G mode when the second determining unit 230 does not find the SIM card and satisfies the three conditions. The SIM card one executing unit 240 is implemented by, for example, a 2G module, a 3G module, an intersystem reselection control module, and a 4G module of a SIM card one in the mobile terminal.

The second SIM card execution unit 250 is configured to store information of a mobile communication operator, a working mode, a service state, a current resident cell, and the like in a shared memory area in real time. The second SIM card execution unit 250 is implemented by, for example, a 2G module, a 3G module, and a 4G module of the second SIM card in the mobile terminal.

Preferably, the shared storage unit 210 employs a read-write operation protection mechanism to avoid data collision when multiple SIM cards read and write the shared memory area at the same time. The read-write operation protection mechanism, for example, uses a static global variable to define a dedicated data structure as the shared memory area, where data is managed in a member variable manner. Each time of reading and writing operation only aims at a certain specific member variable, through a task priority mechanism provided in the real-time multi-task operating system, a certain software module task occupies the shared memory area, and when a certain member variable is read and written in the shared memory area, the other software modules cannot rewrite the member variable at the same time, so that access conflict of data in the shared memory area can be avoided.

Preferably, one of the conditions "the time when the inter-system measurement needs to be started" determined by the first determining unit 220 is, for example, when the first SIM card is in the 2G or 3G operating mode, if any other SIM card (for example, the second SIM card) initiates a service with a higher priority, the scheduling mechanism interrupts the action of the first SIM card, the first SIM card enters the suspended state, and the underlying resource is allocated to the second SIM card for use. And when the high-priority service of the SIM card II is finished, the scheduling mechanism can restore the running state of the 2G or 3G mode of the SIM card I, and the SIM card I does not start the inter-system measurement in the 2G or 3G mode after obtaining the bottom layer resource and restoring the running.

Preferably, the SIM card one executing unit 240 is further configured to reselect the SIM card one to the 2G or 3G mobile communication network, that is, to still be in the 2G or 3G operating mode, when the SIM card one fails to camp on the target cell.

The multi-card multi-4G mobile terminal and the network reselection method thereof have the following beneficial technical effects.

Firstly, after a certain SIM card in the multi-card multi-4G mobile terminal reselects to reside in the 2G or 3G mobile communication network, the SIM card can quickly reselect back to the 4G mobile communication network when meeting specific conditions, thereby improving the network reselection process.

Secondly, when the specific conditions are met, the 4G mobile communication network is reselected quickly, so that unnecessary measurement and cell switching processes can be reduced, the failure rate of mobile phone services caused by cell reselection is reduced, and the smoothness degree of the services is increased.

Thirdly, when the specific conditions are met, the 4G mobile communication network is reselected quickly, so that the power consumption of the mobile terminal can be reduced, and the standby time and the battery life of the mobile terminal can be prolonged.

The above are merely preferred embodiments of the present application and are not intended to limit the present application. Various modifications and changes may occur to those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for reselecting a network by a multi-card multi-4G mobile terminal is characterized by comprising the following steps:

step S110: establishing a shared memory area which can be accessed by all SIM cards; the software module belonging to any SIM card is allowed to access the shared memory area in the working process, and the mobile communication operator, the working mode, the service state and the current resident cell of each SIM card are stored in the shared memory area in real time;

step S120: when the first SIM card is in the 2G or 3G working mode, the first SIM card does not start the inter-system measurement in the 2G or 3G mode at the time when the inter-system measurement needs to be started, but reads the information of the mobile communication operators, the working modes and the service states of the other SIM cards from the shared memory area;

step S130: if the second SIM card in the shared memory region simultaneously meets three conditions, namely the second SIM card and the first SIM card belong to the same mobile communication operator, the second SIM card works in a 4G mode, and the current service state of the second SIM card is normal service, the first SIM card does not start inter-system measurement, and the step S150 is entered;

step S140: if the SIM cards meeting the three conditions simultaneously do not exist in the shared memory area, the SIM card recovers to start the inter-system measurement in the 2G or 3G mode;

step S150: and the SIM card I directly reads the 4G cell where the SIM card II currently resides from the shared memory area, and takes the cell as a target cell for 4G reselection of the SIM card I, and initiates the resident process from the target cell to the 4G mobile communication network.

2. The method of claim 1, wherein in step S110, the shared memory area has a read/write protection mechanism to avoid data collision when multiple SIM cards are read/written simultaneously.

3. The method according to claim 2, wherein the read-write operation protection mechanism uses a static global variable to define a dedicated data structure as the shared memory area, and data in the dedicated data structure is managed by a member variable; each time of reading and writing operation only aims at one member variable, through a task priority mechanism provided in the real-time multi-task operating system, a certain software module task occupies the shared memory area, and when one member variable is read and written, other software modules cannot rewrite the member variable at the same time, so that access conflict of data in the shared memory area can be avoided.

4. The method according to claim 1, wherein in step S120, the time when inter-system measurement needs to be started refers to when the first SIM card is in a 2G or 3G operating mode, if there is another SIM card initiating a service with a higher priority, the scheduling mechanism interrupts the action of the first SIM card, the first SIM card enters a suspended state, and the underlying resource is allocated to the SIM card initiating the service with the higher priority for use; and when the high-priority service of the SIM card initiating the higher-priority service is finished, the scheduling mechanism can restore the running state of the 2G or 3G mode of the SIM card I, and after the 2G or 3G module of the SIM card I obtains the bottom layer resource and restores running, the inter-system measurement in the 2G or 3G mode is not started for a while.

5. The method according to claim 1, wherein in step S130, the 2G or 3G module of the first SIM card no longer starts inter-system measurement, and directly sends a reselection request command to the inter-system reselection control module of the first SIM card, so as to request to directly reselect to the 4G mobile communication network using the currently camped 4G cell information of the second SIM card, and then the 2G or 3G module of the first SIM card enters the inactive state from the active state.

6. The method of claim 5, wherein in step S150, when the inter-system reselection control module of the first SIM card receives a reselection request command sent by the 2G or 3G module of the first SIM card and requests to reselect to the 4G mobile communication network directly using the information of the currently camped 4G cell of the second SIM card, the inter-system cell reselection from GERAN or UTRAN to E-UTRAN (inter-system cell reselection from GERAN/UTRAN to E-UTRAN) is sent to the 4G module of the first SIM card, and the currently camped 4G cell of the second SIM card is designated as a reselection target cell; after receiving the instruction, the 4G module of the SIM card I enters an activated state from an inactivated state; the 4G module of the SIM card I acquires the information of the 4G cell currently resident by the 4G module of the SIM card II through a shared memory area, takes the information as a target cell reselected by the 4G and resides in the 4G target cell; and after the residence is successful, the 4G module of the SIM card I replies a signal of successful reselection of intersystem cell reselection from GERAN or UTRAN to E-UTRAN to the intersystem reselection control module of the SIM card I.

7. The method of claim 1, wherein in step S150, if the SIM card fails to camp on the target cell, the SIM card reselects to the 2G or 3G mobile communication network, i.e. the 2G or 3G mobile communication network is still in the 2G or 3G operation mode, and the process returns to step S120.

8. A multi-card multi-4G mobile terminal is characterized by comprising a shared storage unit, a first judgment unit, a second judgment unit, a first SIM card execution unit and a second SIM card execution unit;

the shared memory unit is used for establishing a shared memory area which can be accessed by all the SIM cards;

the first judging unit is used for judging whether any SIM card is in a 2G or 3G working mode and needs to start inter-system measurement; if yes, the SIM card is called as a first SIM card;

the second judging unit is used for judging whether an SIM card in the shared memory area simultaneously meets three conditions, namely the SIM card and the SIM card belong to the same mobile communication operator, the SIM card works in a 4G mode, and the current service state of the SIM card is normal service; if yes, the SIM card is called as a second SIM card;

the SIM card executing unit is used for storing a mobile communication operator, a working mode, a service state and a current resident cell in a shared memory area in real time; the SIM card executing unit is also used for temporarily not starting the inter-system measurement in the 2G or 3G mode when the first judging unit finds the SIM card meeting the requirement, but reading the information of the mobile communication operator, the working mode and the service state of the other SIM cards from the shared memory area; the first SIM card execution unit is further used for enabling the first SIM card not to start inter-system measurement when the second judgment unit finds the second SIM card meeting the requirement, requiring the first SIM card to directly read the currently resident 4G cell of the second SIM card from the shared memory area, and serving as a target cell for 4G reselection of the first SIM card, and initiating reselection of a resident process to the target cell to the 4G mobile communication network; the first SIM card execution unit is further used for recovering the first SIM card to start the inter-system measurement in the 2G or 3G mode when the second judgment unit does not find the SIM card and meets the three conditions;

the SIM card two execution units are used for storing a mobile communication operator, a working mode, a service state and a current resident cell in a shared memory area in real time.

9. The multi-card multi-4G mobile terminal of claim 8, wherein the SIM-card execution unit is further configured to reselect the SIM card to the 2G or 3G mobile communication network as soon as the SIM card fails to camp on the target cell, i.e. the SIM card is still in the 2G or 3G operation mode.

10. The multi-card multi-4G mobile terminal of claim 8, wherein the shared memory unit is implemented by a memory management subsystem and a thread scheduling subsystem in a processor and an operating system of the mobile terminal;

the first judging unit is realized by a processor of the mobile terminal and a 2G module and/or a 3G module of each SIM card;

the second judgment unit is realized by a processor of the mobile terminal and a 2G module and/or a 3G module of each SIM card;

the SIM card I execution unit is realized by a 2G module, a 3G module, an intersystem reselection control module and a 4G module of an SIM card I in the mobile terminal;

the second SIM card execution unit is realized by a 2G module, a 3G module and a 4G module of a second SIM card in the mobile terminal.