CN100396150C - A reselection method for public land mobile network - Google Patents

Abstract

The present invention discloses a reselecting method for public land mobile networks (PLMN). In the present invention, firstly an HPLMN parameter of a terminal is recorded in a USIM; then, a timer is arranged in a universal subscriber identification module (USIM); subsequently, whether the current public land mobile networks (PLMN) are same is judged according to the mutual information a terminal device and the universal subscriber identification module when the timer reaches a predetermined cycle; if the current public land mobile networks (PLMN) are different, mutual information is returned to the HPLMN parameter of the public land mobile network of the terminal according to the HPLMN parameter of the public land mobile network. In the present invention, the timer is arranged in an STK module with a secondary development function so a short search cycle is reset according to time dimension which can be accepted by the terminal; then, the cycle is returns to the HPLMN, of the terminal according to the stored associated information of the HPLMN in the USIM; therefore, the rapid reselecting function of the PLMN is realized.

Description

A reselection method for public land mobile network

technical field

The present invention relates to a mobile communication network, in particular to a network reselection technology when multiple public land mobile networks overlap and cover, and in particular to a method for a terminal to return to the public land mobile network to which it belongs.

Background technique

In the current mobile communication network, the mobile network of the mobile operator is called PLMN (PublicLand Mobile Network, public land mobile network), and its unique identifier PLMNID is composed of MCC (Mobile Country Code, mobile country code) and MNC (Mobile Network Code, Mobile Network Code) composition. MCC generally contains three numbers, which are used to uniquely identify the country code where the mobile terminal is located. For example, 460 is used to identify China; MNC generally uses two to three numbers to identify the mobile network selected by the mobile terminal. MNCs are different. The same network as the MCC and MNC in the mobile network and the MCC and MNC in the IMSI (International Mobile Subscriber Identity, International Mobile Subscriber Identity) is called the user's home network, which is usually represented by HPLMN (HomePLMN, home PLMN). When the user is in the HPLMN network, it means that the user has not roamed between different operator networks at this time; the network whose MCC and MNC in the mobile network are different from the MCC and MNC in the IMSI is called VPLMN (Visited PLMN, visiting public land mobile network), when the user is in VPLMN network, it means that the user is roaming between networks of different operators.

At present, because different PLMN networks have different coverage areas, the mobile terminal may roam or switch to other networks at any time during the communication process. In order to ensure that mobile terminals use this network preferentially, it is required that once a terminal roaming to another network returns to an area covered by this network, the mobile terminal should return to its HPLMN network as soon as possible.

In the prior art, the HPLMN reselection is implemented based on the HPLMN periodic search principle defined by the 3GPP specification. The mobile terminal and the USIM (Universal Subscriber Identity Module, Universal Subscriber Identity Module) perform information exchange every 30ms or so. The message contains information such as the MNC and MCC of the mobile terminal. The USIM sets a certain search cycle and periodically Detect whether the communication reaches other PLMN coverage areas through the MNC and MCC information, that is, judge whether the current MNC and MCC information is consistent with the MNC and MCC information stored in the IMSI of the USIM. When judging that the current terminal is roaming and is in an idle state, the terminal starts searching for the HPLMN according to the period, so as to return to the HPLMN in time.

However, since the current PLMN reselection search cycle set in the protocol is generally 6 minutes to 8 hours, that is, the shortest time for users who switch or roam to the GSM network to return to the 3G network is 6 minutes. The simple voice service of GSM can be used, so some bandwidth-based characteristic services of 3G will be affected. For example, the videophone based on 3G network will not be available; the packet domain data service attached to the GPRS network can only use GPRS The actual business rate, rather than the high-speed data business of WCDMA packet data business.

Therefore, the HPLMN reselection method in the prior art will have a certain impact on 3G services due to the long reselection time.

Contents of the invention

The technical problem to be solved by the present invention is to provide a public land mobile network reselection method, which can realize fast reselection of the public land mobile network.

In order to solve the above-mentioned technical problems, the present invention provides a kind of reselection method of public land mobile network PLMN, it is characterized in that, comprises steps:

1) Record the attribution public land mobile network HPLMN parameter of the terminal in the Universal Subscriber Identity Module USIM;

2) A timer is set in the Universal Subscriber Identity Module USIM;

3) When the predetermined period of the timer is reached, judge whether the current public land mobile network PLMN is the same according to the interaction information between the terminal equipment and the Universal Subscriber Identity Module USIM;

4) If they are not the same, reselect the network according to the HPLMN parameters of the home public land mobile network and set the reselection flag, and return to the home public land mobile network HPLMN of the terminal;

5) Before performing reselection again, it is judged according to the reselection flag whether there is a reselection record within a predetermined time period, and if yes, the predetermined period of the timer is extended, and the reselection flag is updated after each reselection.

Wherein, the switching process described in step 4) is specifically:

41) Write the parameter into the file of the public land mobile network PLMN with the highest priority;

42) Initiate hot reset information to the terminal;

43) Obtain the parameter from the file, and return to the home public land mobile network HPLMN of the terminal according to the current state of the terminal.

Wherein, the record in step 1) is a permanent record.

Wherein, the parameter includes the frequency point information of the home public land mobile network.

Wherein, the interaction information includes a mobile country code MCC, a mobile network code MNC and a location area code LAC.

Wherein, the method further includes: after the terminal returns to the home public land mobile network HPLMN, the USIM cancels the timer, and clears the reselection mark on the USIM.

Wherein, the public land mobile network PLMN with the highest priority in step 41) is the last registered public land mobile network RPLMN.

Wherein, the process of returning according to the current state of the terminal in step 43) is specifically: returning when the terminal is in an idle state.

Compared with the prior art, the beneficial effect of the present invention is: the present invention sets the timer in the secondary development function module of STK (SIM Development Tools Kit, SIM card development kit) provided in the USIM, according to the acceptable time of the terminal The limit resets a shorter search cycle, and then returns the HPLMN where the terminal is located according to the relevant information of the HPLMN stored in the USIM, thereby realizing the fast reselection function of the PLMN.

Further, in order to prevent the terminal from continuously reselecting multiple HPLMNs within the relatively short search period set by the USIM, the present invention sets a flag that records whether HPLMN reselection occurred last time, and passes through this flag first when performing fast reselection again. Check whether fast reselection has just occurred, and if so, extend the search cycle set in the USIM, thereby avoiding the phenomenon of ping-pong reselection, and further optimizing the present invention.

Compatible with it, the present invention stipulates that once the terminal returns to the home network HPLMN, the USIM will no longer activate the HPLMN fast reselection function, that is, the timer in the USIM will be invalidated, and the HPLMN reselection mark on the USIM will be refreshed, so that it will not be reselected in the future. When handover or roaming occurs, reselection can be continued according to the basic HPLMN reselection function in the prior art.

In addition, the present invention permanently records in the USIM the parameters such as the frequency point necessary for judging the HPLMN of the terminal, so that the terminal does not need to try to select all the PLMNs in the current area after the hot reset, but directly performs the selection according to the HPLMN information recorded in the USIM. The HPLMN chooses to try, thereby reducing the access time.

At the same time, the present invention writes the HPLMN-related parameters recorded in the USIM into the PLMN-related file of the USIM with the highest priority level after the terminal hot reset, so that the terminal first searches for the HPLMN-related information from the file, thereby further speeding up the network reselection time .

Description of drawings

Fig. 1 is a flowchart of a specific embodiment of the present invention.

Detailed ways

After the mobile terminal MS is turned on or in the roaming state, its primary task is to find the network and get in touch with the network to obtain services. The purpose of PLMN selection/reselection is to select an available PLMN. The content of the PLMN file is initialized by the operator and can be modified by the user through the interface provided by the terminal. Doing so can provide some convenience to users, especially users who often roam internationally, and meet the preferences and needs of users themselves. For example, when a Chinese mobile user roams abroad, there are several PLMNs in the local area, and these PLMNs have signed roaming agreements with China Mobile, then the user can choose a PLMN according to the service quality, type and preference of each PLMN to obtain their own more satisfactory service.

To achieve this purpose, MS will maintain a list of PLMNs, which are stored in the relevant file EFPLMN of the USIM, and arrange the PLMNs according to priority. Drill down to find the PLMN with the highest priority. The selection and reselection of PLMN has two modes: automatic and manual. During automatic network selection, the MS automatically selects a PLMN according to the priority order of the PLMNs. Manual network selection presents all currently available networks to the user, and the user selects a PLMN. Regardless of whether it is automatic network selection or manual network selection, after the MS is powered on, it will first try RPLMN (Registered PLMN), that is, the PLMN that was successfully registered last time, and there will be no follow-up operations after success; if it is unsuccessful, the MS will generate one according to the priority. PLMN list, HPLMN has the highest priority in this list.

When the following two situations occur, PLMN reselection is required:

1) In any case, the user can manually request to initiate PLMN reselection;

2) If the communication is switched to another PLMN, this PLMN is called the user registers to VPLMN (Visited PLMN, access to the public land mobile network), and the user registers to the VPLMN network reselection: after the user registers to the VPLMN due to switching/roaming, etc., Since the MCC of the VPLMN and the HPLMN are the same, only the MNC is different, the MS can judge this situation and try to return to the HPLMN of the network it belongs to. The specific measure is that the MS searches for the home network periodically. The period in the prior art is specified by the USIM and defined in the related file EF _HPLMN of the USIM, ranging from 6 minutes to 8 hours.

The present invention provides a method for quickly selecting a PLMN, the core of which is to set a new search time according to the user's acceptable time limit through secondary development of the STK function module for the user in the USIM.

When using the present invention, first record the basic parameters of the public land mobile network HPLMN of the terminal in the Universal Subscriber Identity Module USIM, and the parameters are relevant parameters necessary for reselecting the PLMN, such as frequency points, etc.;

Then set the timer in the Universal Subscriber Identity Module USIM, and set the search cycle acceptable to the user; this cycle can be set according to the user's requirements for the service;

When the predetermined period of the timer is reached, judge whether the current public land mobile network PLMN is the same according to the interaction information between the terminal equipment and the Universal Subscriber Identity Module USIM. The method for judging whether the PLMN is the same is the same as the prior art, and the specific judgment method will be Describe in detail in conjunction with the embodiment below;

If they are not the same, switch to the terminal’s home public land mobile network HPLMN according to the home public land mobile network HPLMN parameters. When selecting, directly reselect to HPLMN quickly according to the relevant parameters of HPLMN.

In order to prevent the terminal from continuously reselecting multiple HPLMNs within the relatively short search period set by the USIM, the present invention sets a flag that records whether HPLMN reselection occurred last time. Reselection has occurred, if so, the search period set in the USIM is extended, thereby avoiding the phenomenon of ping-pong reselection, and further optimizing the present invention.

Compatible with it, the present invention stipulates that once the terminal returns to the original network, the USIM will no longer activate the HPLMN fast reselection function, that is, the timer in the USIM will be invalidated, and the HPLMN reselection mark on the USIM will be cleared, so that it can be used in the future. The base can continue to perform reselection according to the basic HPLMN reselection function of the prior art.

In the present invention, the parameters such as the frequency point necessary for judging the HPLMN of the terminal are permanently recorded in the USIM, so that the terminal does not need to try to select all the PLMNs in the current area after the hot reset, but directly according to the HPLMN information recorded in the USIM An HPLMN selection attempt is made, thereby reducing the access time.

At the same time, the present invention writes the HPLMN-related parameters recorded in the USIM into the PLMN-related file of the USIM with the highest priority level after the terminal hot reset, so that the terminal first searches for the HPLMN-related information from the file, thereby further accelerating the reselection time.

A typical application of the present invention is the WCDMA system of the third generation mobile communication (abbreviated as 3G). Because the coverage of WCDMA is not as wide as that of GSM network, 3G users will roam or switch to GSM network at any time. In order to realize that WCDMA users can be automatically selected from GSM network to WCDMA network when they enter the coverage area of WCDMA network, WCDMA and GSM networks can be set as different PLMNs, and WCDMA can be set as HPLMN in USIM. Through PLMN reselection, users can return to WCDMA network as soon as possible from GSM network. The process of using the present invention will be described in detail below as a preferred embodiment of the present invention.

The first embodiment: In this embodiment, firstly, the basic parameters of the WCDMA mobile operator are permanently recorded in the USIM. The basic parameters include basic information such as frequency points. In the prior art, these basic parameters are temporarily saved. If the user shuts down the phone for a long time, the USIM will clear the stored information. When the terminal is powered on again, the MS will scan all available frequency points in the current area, and then Once the access attempt is made, the present invention adopts the method of permanently recording the parameters necessary for selecting the PLMN network, so that the terminal does not need to try all the PLMNs in the current area after the hot reset, but according to the frequency point information recorded in the USIM The corresponding frequency point cut-in attempt is directly performed, thereby shortening the access time.

As mentioned above, since the search period in the prior art is defined in the related file EF _HPLMN of USIM as 6 minutes to 8 hours, too long search time cannot meet the needs of users for services, and if the existing The modification of the protocol will involve the readjustment of the network by each operator, which will affect the stability of the existing network. Therefore, in this embodiment, a timer is additionally set in the functional module of the USIM for secondary development by the user. The search time is set to a relatively short period.

In addition, the present invention makes full use of the interaction information between the mobile phone terminal equipment and the USIM to judge whether it is necessary to perform PLMN network reselection at present. The message exchange interval between the mobile terminal and the USIM is generally about 30ms. The message will contain MCC information, MNC information and LAC (Location area code) information necessary for the terminal to enter another PLMN. If the message contains If the MCC, MNC and other information in the IMSI are the same as the MCC but different from the MNC stored in the IMSI, then it is judged that cross coverage occurs in the network.

In order to avoid coverage blindness of WCDMA already covered by GSM and repeatedly perform HPLMN fast reselection, the USIM can record the last HPLMN fast reselection flag, for example, mark the flag as True or False, indicating whether network reselection has been performed.

Fig. 1 is a flowchart of network reselection using the present invention. As shown in the figure, after the user registers to the VPLMN due to switching/roaming and other reasons, when the handshake timer reaches the time, the mobile terminal device will perform information interaction with the USIM (step 1);

When the search period of the reselection timer customized by the USIM is reached, the USIM acquires the above information attached to the network (step 2);

USIM judges the basic information of the GSM network that the current terminal roams to, such as MCC, MNC, LAC, etc., to judge whether there may be cross coverage with 3G, and the specific judgment principle is determined by the basic functions of the mobile phone (step 3);

If the detected MNC is the same as the MNC in the IMSI, it means that the user is not in the network of other operators, and the HPLMN fast reselection based on the USIM card will not be performed; otherwise, if the mobile phone has detected the coverage information of GSM and WCDMA, that is If it is judged that HPLMN reselection is required, the USIM initiates the following actions:

When performing reselection, first check the pre-set reselection flag. If it is found that multiple consecutive reselections have been performed within a short period of time, the USIM will change the HPLMN reselection time interval, prolong the search period appropriately, and refresh the flag at the same time ( Step 4), thereby further optimizing the present invention, avoiding possible ping-pong reselection phenomenon;

Judging whether it meets the HPLMN reselection conditions controlled by the USIM (step 5), if not, then do not perform reselection, otherwise, when it is judged that reselection is required, write the permanent WCDMA network related parameters recorded in the USIM into the RPLMN of the USIM List (step six); there is a file EF _LOCI in the USIM card, and in this file, MCC and MNC are recorded. The purpose of this step is mainly designed according to the current 3GPP TS 31.102 related protocol, which stipulates that after the MS starts up, it first tries RPLMN reselection, and the purpose is to speed up the reselection speed.

Then, the USIM initiates a warmRest command to the terminal to force the terminal to perform a warm start or simulate a manual network selection method (step 7), so that the terminal re-attempts to select the RPLMN. According to the information of the RPLMN in the above steps, there is no need to re-search the information in the air. Directly locate to the HPLMN (step eight) that needs to be reselected, accelerate the reselection of HPLMN;

Once the user returns to the WCDMA HPLMN network, the USIM card will no longer activate the HPLMN fast reselection, and clear the HPLMN fast reselection mark on the USIM, and then use the basic HPLMN reselection function defined by 3GPP.

Considering the future development trend of the communication field, the present invention is not limited to HPLMN network reselection, but can also be applied to the situation that a mobile terminal performs network reselection among other PLMN networks.

The above is only a preferred embodiment of the present invention, it should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, some improvements and modifications can also be made, and these improvements and modifications should also be It is regarded as the protection scope of the present invention.

Claims (8)

1. A reselection method of public land mobile network PLMN, is characterized in that, comprises steps: 1) Record the attribution public land mobile network HPLMN parameter of the terminal in the Universal Subscriber Identity Module USIM; 2) A timer is set in the Universal Subscriber Identity Module USIM; 3) When the predetermined period of the timer is reached, judge whether the current public land mobile network PLMN is the same according to the interaction information between the terminal equipment and the Universal Subscriber Identity Module USIM; 4) if not the same, then reselect the network according to the HPLMN parameters and set the reselection mark to return to the HPLMN of the terminal; 5) Before performing reselection again, it is judged according to the reselection flag whether there is a reselection record within a predetermined time period, and if yes, the predetermined period of the timer is extended, and the reselection flag is updated after each reselection. 2. The method for reselecting a public land mobile network according to claim 1, wherein the handover process in step 4) is specifically: 41) Write the parameter into the file of the public land mobile network PLMN with the highest priority; 42) Initiate hot reset information to the terminal; 43) Obtain the parameter from the file, and return to the home public land mobile network HPLMN of the terminal according to the current state of the terminal. 3. The method for switching public land mobile networks according to claim 1 or 2, characterized in that the record in step 1) is a permanent record. 4. The reselection method of the public land mobile network according to claim 1 or 2, characterized in that, the parameters include home public land mobile network frequency point information. 5. The method for reselecting a public land mobile network according to claim 1, wherein the interaction information includes a mobile country code (MCC), a mobile network code (MNC) and a location area code (LAC). 6. The method for reselecting a public land mobile network according to claim 1, further comprising: After the terminal returns to the home public land mobile network HPLMN, the universal subscriber identity module USIM cancels the timer and clears the reselection mark on the universal subscriber identity module USIM. 7. The method for reselecting a public land mobile network according to claim 2, wherein the public land mobile network PLMN with the highest priority in step 41) is the public land mobile network RPLMN registered last time. 8. The method for reselecting a public land mobile network according to claim 2, wherein the process of returning according to the current state of the terminal in step 43) is specifically: Returned when the terminal is idle.

Images