KR100588200B1 - Mobile communication system and method of public land mobile network searching the same - Google Patents

Abstract

The present invention relates to a method for retrieving a public land mobile network of a mobile communication system, the method comprising: searching for a PLMN (Public Land Mobile Network) when power is applied to a mobile communication terminal and registering the PLMN with the highest priority; Checking whether the registered PLMN is an HPLMN (Home PLMN); If the currently registered PLMN is not an HPLMN, checking system information provided by the PLMN based on system information to determine whether a search for HPLMN is permitted; If the search of the HPLMN is not allowed, characterized in that it comprises the step of stopping the search of the HPLMN. This improves the search efficiency of the home PLMN by managing whether the home PLMN (Public Land Mobile Network) of the mobile communication terminal is searched in the network when using the roaming function, thereby preventing battery consumption due to unnecessary home PLMN search at the visited place. Can be.

Description

Search Method for Public Land Mobile Network of Mobile Communication System {MOBILE COMMUNICATION SYSTEM AND METHOD OF PUBLIC LAND MOBILE NETWORK SEARCHING THE SAME}

1 is a flowchart illustrating a home PLMN search method when roaming is registered in a conventional mobile communication system.

2 is a configuration diagram of a PLMN of a mobile communication system according to the present invention;

3 is a control block diagram of the mobile communication system of FIG.

4 is a flowchart illustrating a home PLMN search method when roaming is registered in a mobile communication system according to a first embodiment of the present invention;

5 is a flowchart illustrating a home PLMN retrieval method when roaming is registered in a mobile communication system according to a second embodiment of the present invention;

6 is a flowchart illustrating a home PLMN search method when roaming is registered in a mobile communication system according to a third embodiment of the present invention.

*** Explanation of symbols for the main parts of the drawing ***

 1: V-PLMN 5: H-PLMN

10: V-MSC 12: V-BSC

14: V-BST A 16: V-BST B

50: H-MSC 52: H-BSC

54: H-BST

The present invention relates to a method for retrieving a public land mobile network of a mobile communication system, and in particular, by managing whether a home PLMN (Public Land Mobile Network) of a mobile communication terminal is searched in a network when using a roaming function, thereby improving the search efficiency of a home PLMN. The present invention relates to a method for retrieving a public land mobile network of a mobile communication system that prevents battery consumption due to unnecessary home PLMN search at a visited place.

GSM (Global System for Mobile communication) supports roaming function to use a public land mobile network (Public Land Mobile Network, hereinafter referred to as PLMN) serviced by different operators as one mobile communication terminal.

When the mobile terminal roams to a service area (Visited PLMN, hereinafter referred to as VPLMN) of a service provider other than the home PLMN, a search for finding a home PLMN according to a cycle set in a subscriber identity module (SIM) card. Is carried out.

1 is a flowchart illustrating a home PLMN retrieval method for roaming registration in a conventional mobile communication system.

When power is applied and driving starts (P10), the mobile communication terminal first searches for a PLMN (P12). When the search is completed, the search is performed by searching the network with the highest priority in the search results. For example, HPLMN, a user-specified PLMN selected in SIM, a field PLMN of -85 dBm or more, and a field PLMN of -85 dBm or less. Access may be attempted in the order of. In other words, when the mobile communication terminal is registered in the VPLMN, the HPLMN is first accessed according to the priorities, and when the HPLMN is difficult to access, the PLMN stored in the SIM is accessed, and the SIM-adopted PLMN is difficult to access. Access to field PLMNs of -85dBm or higher, and access to field PLMNs of -85dBm or lower when accessing SIM-adopted PLMNs is difficult.

Accordingly, the mobile communication terminal receives and decodes the system information of the PLMN having the highest priority (P14), and registers the PLMN according to the received information (P16).

When the registration is completed, it is checked whether the currently registered PLMN is an HPLMN (P18). As a result of the determination, when the currently registered PLMN is an HPLMN, since the registration is properly registered in the HPLMN (P20), the search for the HPLMN is terminated.

On the other hand, if the currently registered PLMN is not HPLMN, since it is registered in the VPLMN (P24), it performs the HPLMN search again (P26), and registers with the HPLMN (P22).

If the HPLMN is not found, the mobile communication terminal searches for the PLMN, obtains system information of the PLMN having the highest priority (P28), and registers the PLMN according to the received information (P30). Accordingly, by repeating the operation of checking whether or not the HPLMN registration again in step P18 to find and register the HPLMN.

As described above, in the conventional mobile communication system, when the mobile communication terminal is registered in the roaming network (VPLMN, Visited PLMN), the HPLMN is periodically searched. Here, the HPLMN search period is set in advance and is a subscriber identity module (SIM). Stored in. The HPLMN search cycle is typically about 30 minutes, and the search cycle can be reset by the over the air technique, so the search cycle may be set to 6 minutes depending on the service provider.

However, the service network is generally composed of unit cells, so that the signal of the service provider becomes stronger as it goes to the center of the network, while the distance from the base station of the other network is farther away. As the position of the mobile communication terminal approaches the center of the network, the signal of another network Is less likely to be received. On the other hand, if you are located at the boundary of roaming networks, you will likely find other networks.

That is, in the conventional mobile communication system, when the mobile communication terminal is registered in the service network (VPLMN) of the visited place, the HPLMN is searched according to the search period set in the SIM, so that the PLMN search is performed even in areas where it is difficult to find another PLMN or in unnecessary areas. Attempts have been made to cause waste of battery power.

The present invention has been made to solve the above-mentioned problems, by using the roaming function to improve the search efficiency of the home PLMN by managing whether the home PLMN (Public Land Mobile Network) search of the mobile communication terminal in the network, An object of the present invention is to provide a method for retrieving a public land mobile network of a mobile communication system that prevents battery consumption due to unnecessary home PLMN search.

In accordance with another aspect of the present invention, there is provided a method for retrieving a public land network of a mobile communication system according to the present invention, the method comprising: searching for a PLMN (Public Land Mobile Network) when power is applied to a mobile communication terminal and registering the PLMN with the highest priority Wow; Checking whether the registered PLMN is an HPLMN (Home PLMN); If the currently registered PLMN is not an HPLMN, checking system information provided by the PLMN based on system information to determine whether a search for HPLMN is permitted; If the search of the HPLMN is not allowed, characterized in that it comprises the step of stopping the search of the HPLMN.

Reselecting a serving cell of the mobile communication terminal according to the movement of the mobile communication terminal; Checking whether the HPLMN is allowed to be searched by checking system information of the reselected serving cell; If the search of the HPLMN is not allowed, it is possible to include the step of stopping the search of the HPLMN.

 And starting a search timer when the search of the HPLMN is allowed; Determining whether the HPLMN has been searched before the time set in the search timer has elapsed; If the HPLMN search fails, it is possible to further include the step of searching for and registering the highest priority PLMN.

Hereinafter, with reference to the accompanying drawings will be described in detail with respect to the aerial land mobile network search method of the mobile communication system according to an embodiment of the present invention.

2 is a diagram illustrating a network of a mobile communication system according to the present invention, illustrating a service cell of a public land mobile network (hereinafter referred to as PLMN) serviced by different operators. The mobile communication terminal A (Mobile Station A, hereinafter referred to as MSA) 100 and the mobile communication terminal B (Mobile Station B, hereinafter referred to as MSB) 200 shown in FIG. 2 are referred to as home PLMNs (hereinafter referred to as MSBs). Roaming is registered in a service area (Visited PLMN, hereinafter referred to as V-PLMN) 1 of a service provider other than (5).

PLMN (1, 5) is composed of a cell centered on a base station providing a radio link, in the case of a unit cell (Cell A) located in the center of the PLMN (1, 5) the outer periphery of the PLMN (1, 5) Compared to the unit cell (Cell B) located in, it is less likely that a signal of another PLMN is received. As a result, the MS 100 or 200 is allowed or prohibited from searching for the H-PLMN 5 depending on the unit cell.

2, the MSA 100 and the MSB 200 are currently registered in the V-PLMN 1, but in the case of the MSA 100, a unit cell (Cell A) located at the center of the V-PLMN 1 is shown. Because it is located at, the probability of finding the H-PLMN 5 is low, and even if it is found, the reception level is low, so it will be difficult to receive the service. Accordingly, the unit cell Cell A located at the center of the V-PLMN 1 prohibits the MSA 100 from searching the H-PLMN 5.

On the other hand, in the case of a unit cell (Cell B) located at the outer part of the V-PLMN (1) and close to the H-PLMN (5), the MSB (200) is easy to search for the H-PLMN (5). Search for the PLMN 5. That is, the MSs 100 and 200 registered in the V-PLMN 1 allow the H-PLMN 5 search only when located at or moved to the boundary region Cell B of the V-PLMN 1. This improves search efficiency and saves battery power.

3 is a control configuration diagram of a mobile communication system according to the present invention, schematically showing each control element constituting the network of FIG. As shown in FIG. 3, the mobile communication system includes a base station controller (Base Transceiver Station, BTS) 14, 16, 54 for transmitting and receiving a radio signal and a BTS 14, 16, 54. Base Station Controller (hereinafter referred to as BSC) (12, 52) and the MS (100, 200) through the BTS (14, 16, 54) and BSC (12, 52) by controlling the overall service provided by the mobile communication system And a mobile switching center (hereinafter referred to as MSC) 10 and 50 for transmitting and receiving data.

The MSCs 10 and 50 control overall services provided by the mobile communication system to manage mobility of the MSs 100 and 200 through the BTSs 14, 16 and 54 and the BSCs 12 and 52, location registration / management, It handles authentication, handover, and roaming.

The BTSs 14, 16 and 54 of each serving cell provide system information to the MSs 100 and 200 located in the service area through a broadcast control channel (hereinafter referred to as BCCH). Cell management is performed by receiving information such as the operator, identifier, cell location, cell movement, frequency information, etc. of the corresponding cell through system information of the unit cell currently located. Accordingly, the present invention adds the H-PLMN (5) search control value to the system information provided through the BCCH to allow or prohibit the H-PLMN (5) search of the MS (100, 200) located in the service area.

Accordingly, the V-BST A 14 of the unit cell Cell A located at the center of the V-PLMN 1 receives system information of a setting not allowing the H-PLMN 5 to be searched. The V-BST B (16) of the unit cell (Cell B) located at the outer part of the V-PLMN (1) provides the MSB (200) with the system information of the setting allowing the search of the H-PLMN (5). To provide. That is, the MSs 100 and 200 registered in the V-PLMN 1 search or stop the H-PLMN 5 according to the system information of the unit cells Cell A and B which are currently located.

4 to 6, a home PLMN search method in a mobile communication system according to the present invention will be described in detail.

As shown in the flowchart of FIG. 4, when power is supplied to the mobile communication terminal to start driving (S10), the mobile communication terminal first searches for a PLMN (S12). When the search is completed, the search is performed by searching for the network having the highest priority in the search results. For example, HPLMN, a user-specified PLMN selected in SIM, a field PLMN of -85 dBm or more, and a field PLMN of -85 dBm or less. Access may be attempted in order. In other words, when the mobile communication terminal is registered in the VPLMN, the HPLMN is first accessed according to the priorities, and when the HPLMN is difficult to access, the PLMN stored in the SIM is accessed, and the SIM-adopted PLMN is difficult to access. Access to field PLMNs of -85dBm or higher, and access to field PLMNs of -85dBm or lower when accessing SIM-adopted PLMNs is difficult.

Accordingly, the mobile communication terminal receives and decodes the system information of the PLMN having the highest priority (S14), and registers with the corresponding PLMN according to the received information (S16).

When the registration is completed, it is checked whether the currently registered PLMN is an HPLMN (S18), and as a result of the check, when the currently registered PLMN is an HPLMN, since the registration is properly registered in the HPLMN (S20), the search of the HPLMN is terminated.

On the other hand, if the currently registered PLMN is not HPLMN it is registered in the VPLMN (S24), the mobile communication terminal checks the system information provided by the PLMN to determine whether the search of the HPLMN is allowed (S26). ).

Therefore, if the search for HPLMN is allowed, the system enters the state of performing HPLMN search in the state registered in the VPLMN (S30). It enters the state (S28). That is, the mobile communication terminal searches or stops searching for the HPLMN according to the system information provided by the cell to which the mobile communication terminal belongs.

If the state registered in the VPLMN or the search of the HPLMN is not allowed (A), the subsequent HPLMN search control process will be described with reference to FIG.

If the mobile communication terminal stays in an area where it is not easy to receive the signal of the HPLMN, it maintains the state registered in the VPLMN or does not search for the HPLMN (S28).

Herein, when the mobile communication terminal moves, the cell is reselected (S32). Accordingly, the mobile communication terminal may change from an area requiring HPLMN search to an unnecessary area or in the opposite direction. In this case, the VPLMN registration status must also be changed.

If the mobile communication terminal permits the search of the HPLMN in the visited VPLMN, the mobile communication terminal searches for the PLMN, receives and decodes the system information of the PLMN having the highest priority (S34), and registers with the corresponding PLMN according to the received information. (S36).

When the registration is completed, it is checked whether the currently registered PLMN is an HPLMN (S38), and if the currently registered PLMN is an HPLMN, since the registration is properly registered in the HPLMN (S20), the search of the HPLMN is terminated.

Meanwhile, if the currently registered PLMN is not HPLMN, it is still registered in VPLMN (S40). Accordingly, the mobile communication terminal checks the system information provided by the PLMN to determine whether the HPLMN is allowed to be searched (S44). ).

Therefore, if the search for HPLMN is allowed, the system enters the state of performing HPLMN search in the state registered in the VPLMN (S30). It enters the state (S28).

On the other hand, if it is registered in the VPLMN and the search for the HPLMN is also allowed (B), the subsequent HPLMN search control process will be described with reference to FIG.

When the mobile communication terminal is located in the outer region of the VPLMN or moves to the outer side, reception of the HPLMN signal becomes easy, and the serving cell allows the search of the HPLMN (S30).

Accordingly, the mobile communication terminal may perform HPLMN search again (S50), and perform registration of the user in the searched HPLMN (S58), thereby registering in the HPLMN (S20). The search time of the HPLMN search may be set through the HPLMN search timer.

On the other hand, if the HPLMN is not found, the mobile communication terminal searches for the PLMN to obtain system information of the PLMN having the highest priority (S52), and registers with the corresponding PLMN according to the received information (S54).

After the registration is completed, it is determined whether the search of the HPLMN is allowed by checking the system information provided by the PLMN (S56).

Therefore, if the search for HPLMN is allowed, the process returns to the state of performing HPLMN search in the state registered in the VPLMN (S30). It enters the state (S28).

As described above, the present invention manages the home PLMN (Public Land Mobile Network) search of the mobile communication terminal when using the roaming function in the network to increase the probability of finding another network and reduce unnecessary network power consumption by reducing unnecessary network search attempts. Is preventing.

As described above, the embodiment according to the present invention is not limited to the above, and various modifications can be made within the scope apparent to those skilled in the art in connection with the present invention.

As described above, the method for retrieving the public land mobile network of the mobile communication system of the present invention manages whether the home PLMN (Public Land Mobile Network) of the mobile communication terminal is searched in the network when the roaming function is used, and thus the home PLMN is highly searchable We only allow local searches.

Accordingly, the search efficiency of the home PLMN is improved and unnecessary network search attempts are reduced, thereby preventing battery consumption due to unnecessary home PLMN search at the visited place.

Claims (3)

Searching for a PLMN (Public Land Mobile Network) when the power is supplied to the mobile communication terminal and registering the PLMN with the highest priority; Checking whether the registered PLMN is an HPLMN (Home PLMN); If the currently registered PLMN is not an HPLMN, checking system information provided by the PLMN based on system information to determine whether a search for HPLMN is permitted; And stopping the search of the HPLMN when the search of the HPLMN is not permitted. The method of claim 1, Reselecting a serving cell of the mobile communication terminal according to the movement of the mobile communication terminal; Checking whether the HPLMN is allowed to be searched by checking system information of the reselected serving cell; And stopping the search of the HPLMN when the search of the HPLMN is not permitted. The method of claim 1, Starting the search timer when the search of the HPLMN is permitted; Determining whether the HPLMN has been searched before the time set in the search timer has elapsed; And searching for and registering the PLMN having the highest priority, if the HPLMN search fails.

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