KR20050108840A - Method and system for providing international roaming service by using automatic nam selection - Google Patents

Abstract

The present invention relates to a method and system for supporting an international roaming service by automatic NAM selection.

The present invention provides a method of supporting international roaming service by automatic NAM (Number Assignment Module) selection in a mobile communication system including a wireless access network and a mobile switching center. Selecting an initial search frequency for connecting to the system; (b) tuning the mobile communication terminal to a Sync Channel from the selected initial search frequency; (c) checking the SID and NID values received through the sink channel and comparing the SID and NID values registered in the NAM of the mobile communication terminal; And (d) when the SID and NID values compared in the step (c) do not coincide with each other, select a NAM setting in which the SID and NID values received in the sink channel are registered to determine the NAM of the mobile communication terminal. It provides a method and system for supporting the international roaming service by automatic NAM selection, characterized in that it comprises the steps of changing and initializing the mobile communication terminal.

According to the present invention, the NAM is automatically selected by the user of the mobile communication terminal without having to manually set the NAM, so that the international roaming service can be used.

Description

Method and System for Providing International Roaming Service by Using Automatic NAM Selection}

The present invention relates to a method and system for supporting an international roaming service by automatic NAM (Number Assignment Module) selection. In detail, after initializing the mobile communication terminal, the initial search frequency is selected using the PRL of the mobile communication terminal, and the SID and NID values included in the sink channel are checked by tuning to the sink channel from the initial search frequency. A method and system for supporting an international roaming service by automatically selecting a NAM having a domestic or international roaming setting corresponding to the SID and NID value included in a sink channel, compared to the SID and NID values registered in the NAM of will be.

As computer, electronic, and communication technologies have made rapid progress, various wireless communication services using wireless networks have been provided. The most basic wireless communication service is a wireless voice call service that provides a voice call to a mobile terminal user wirelessly, which can provide a service regardless of time and place. In addition, while providing a text message service to complement the voice call service, a wireless Internet service has recently emerged to provide an Internet communication service to a user of a mobile communication terminal through a wireless communication network.

As a result of the development of mobile communication technology, a service provided by a code division multiple access (CDMA) mobile communication system transmits data such as circuit data and packet data as well as voice service. It is developing into a multimedia communication service.

In recent years, with the development of information and communication, IMT-2000 (International Mobile Telecommunication 2000), a third generation mobile communication system that has been standardized by ITU-R (for example, CDMA2000 1X, 3X, EV-DO, WCDMA (WideBand CDMA)) Etc.) are commercially available. IMT-2000 is a CDMA 2000 1X, 3X, EV-DO, WCDMA (WideBand CDMA), etc., which is used in IS-95A and IS-95B networks by using the IS-95C network that has evolved from the existing IS-95A and IS-95B networks. It is a service that can provide wireless Internet at a transmission speed of up to 144 Kbps, much faster than the supportable data transfer rate of 14.4 Kbps or 56 Kbps. In particular, by using IMT-2000 service, it is possible to provide various multimedia services (AOD, VOD, etc.) at higher speed as well as improving existing voice and WAP service quality.

The NAM of the mobile communication terminal directly inputs system and terminal information necessary for call processing from the terminal. When a new mobile communication terminal joins a mobile communication provider, the NAM must be input. A specific value is input to NAM parameters related to system and terminal information by NAM programming, and as NAM parameters, a mobile identification number (MIN), a CDMA frequency band for accessing a mobile communication system, and a system identification number ( SID (System Identification Number), Network Identification Number (NID: Network Identification Number), Device Serial Number (ESN: Electronic Serial Number), Authentication Key (A Key: Authentication Key), SCM (Station Class Mark) and the like. In general, four NAMs can be used, from NAM1 to NAM4, which is for roaming of a mobile communication terminal.

Here, roaming refers to converting a service right so that a service provided by a mobile communication system of a subscription area can be provided by a system of another area. For example, a domestic mobile communication service user may be provided with a mobile communication service using a mobile communication system of an overseas operator through international roaming in order to receive a mobile communication service abroad. If the SID and NID values set in the NAM of the mobile terminal are different from the SID and NID values transmitted from the mobile communication system, the roaming state is established. If the NAM is set to the SID and NID values of the region, the mobile communication system of the region is selected. The mobile communication service can be provided.

1 is an exemplary screen illustrating a NAM configuration of a mobile communication terminal.

As shown in Figure 1, the mobile communication terminal provides a menu for setting the NAM. If you select General from the full menu, you can see general system and terminal information such as ESN, A Key, SCM, etc. If you select one of NAM1 to NAM4, MIN, CDMA frequency band (Primary Channel and Secondary Channel), You can see the parameter values such as SID and NID, and you can change the NAM settings by changing the parameter values. However, since the ESN is a unique number of the mobile communication terminal, the ESN cannot be changed.

Conventionally, in order to use the international roaming service, since the MIN used in Korea and the MIN for outgoing and incoming calls in the international roaming service are different, and the frequency of accessing the mobile communication system in the domestic and foreign countries is different, the NAM setting menu described in FIG. International roaming service was available only after manually setting the NAM for the region, and there was a problem that user inconvenience caused by manual setting was great.

In addition, when a mobile terminal user moves from Korea to an overseas country or moves to a different area, the NAM setting needs to be made manually. And there is a problem that can not provide a continuous mobile communication service because it is impossible to receive.

In order to solve the above problems, the present invention initializes a mobile communication terminal and selects an initial search frequency using a PRL, receives a sink channel, and then checks whether the SID and NID values included in the sink channel are for domestic or international roaming. If the NAM setting of the mobile communication terminal is set for international roaming when the SID and NID values are for domestic use, select the NAM for domestic use and initialize the mobile communication terminal, and when the SID and NID values are for international roaming, It is an object of the present invention to provide a method and system for supporting international roaming services by selecting an NAM for a foreign country, initializing a mobile communication terminal and automatically selecting a NAM suitable for a corresponding region when the NAM setting is set for domestic use.

According to a first object of the present invention, a method for supporting an international roaming service by automatic NAM (Number Assignment Module) selection in a mobile communication system including a wireless access network and a mobile switching center, comprising: (a) initializing a mobile communication terminal; Selecting an initial search frequency for connecting to the mobile communication system; (b) tuning the mobile communication terminal to a Sync Channel from the selected initial search frequency; (c) checking the SID and NID values received through the sink channel and comparing the SID and NID values registered in the NAM of the mobile communication terminal; And (d) when the SID and NID values compared in the step (c) do not coincide with each other, select a NAM setting in which the SID and NID values received in the sink channel are registered to determine the NAM of the mobile communication terminal. Changing and initializing the mobile communication terminal provides a method for supporting international roaming service by automatic NAM selection.

According to a second object of the present invention, a computer-readable recording of an application that implements a method for supporting international roaming service by automatic NAM selection in a mobile communication system including a mobile communication terminal, a wireless access network, and a mobile switching center. In the medium, an initial search frequency for accessing the mobile communication system is selected, the mobile communication terminal is tuned to a sink channel, the SID and NID values received from the sink channel are checked, and the NAM of the mobile communication terminal is checked. If the SID and NID values do not coincide with each other in comparison with the registered SID and NID values, the NAM of the SID and NID values received in the sink channel is selected to change the NAM of the mobile communication terminal. Provides a computer-readable recording medium for recording applications.

According to a third object of the present invention, in a system supporting an international roaming service by automatic NAM selection, after selecting an initial search frequency, the SID and NID values received in the sync channel are registered in the NAM in synchronization with a sync channel. A mobile communication terminal for changing the NAM setting by selecting a NAM in which the SID and NID values received in the sink channel are registered in comparison with an SID and a NID value; A wireless access network for transmitting a message including the SID and NID values to the mobile communication terminal through the sink channel; A mobile telephone exchange station for inquiring whether the HLR is a subscriber of the international roaming service and interworking with an overseas mobile communication network; And an HLR for storing information of the international roaming service subscriber and providing the information to the mobile switching center.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. First of all, in adding reference numerals to the components of each drawing, it should be noted that the same reference numerals are used as much as possible even if displayed on different drawings. In addition, in describing the present invention, when it is determined that the detailed description of the related well-known configuration or function may obscure the gist of the present invention, the detailed description thereof will be omitted.

2 is a block diagram showing the configuration of a system supporting international roaming service by automatic NAM selection according to a preferred embodiment of the present invention.

As shown in FIG. 2, a system supporting international roaming service by automatic NAM selection according to a preferred embodiment of the present invention includes a mobile communication terminal 200, a wireless access network 210, a mobile switching center 220, and a PSTN. It may include a Public Switched Telephone Network (230), an Authentication Center (AC) 240, a Home Location Register (HLR) 250, a Visitor Location Register (VLR) 260, and the like.

The mobile communication terminal 200 according to the preferred embodiment of the present invention initializes the mobile communication terminal 200 when power is applied, and then uses the PRL (Preferred Roaming List) stored in the mobile communication terminal 200. It selects an initial search frequency for accessing the system, and checks whether the NID and SID values received from the sync channel are for domestic or international use by synchronizing with the sync channel and changes the NAM setting of the mobile communication terminal accordingly.

Here, the PRL may select an initial search frequency by searching a frequency channel registered in the PRL as a list including SID, NID, and CDMA channel information. Conventionally, the initial search frequency can be searched only for each primary channel and secondary channel registered in four NAMs, but using PRL, a large number of initial search frequencies and SIDs can be searched. Because it can be searched, it is effective for international roaming service.

Here, the sink channel provides information of important mobile communication systems such as SID and NID, and a process of synchronizing the sync channel with the mobile communication terminal 200 will be described later with reference to FIG. 3.

The mobile communication terminal 200 according to the preferred embodiment of the present invention is a personal digital assistant (PDA), a cellular phone, a personal communication service (PCS) phone, a hand-held PC, a global system for mobile (GSM). Various wired and wireless communication terminals, such as a phone, a wideband CDMA (W-CDMA) phone, a CDMA-2000 phone, and a mobile broadband system (MBS) phone, may be included. Here, MBS phone refers to a mobile communication terminal to be used in the fourth generation system that is currently discussed.

On the other hand, the internal configuration of the mobile communication terminal 200 according to an embodiment of the present invention will be described in more detail with reference to FIG.

The wireless access network 210 according to the preferred embodiment of the present invention transmits a message including mobile communication system information such as SID and NID to the mobile communication terminal 200 through a sync channel. In addition, the mobile station transmits data received from the mobile switching center 220 to the mobile communication terminal 200 through a paging channel, and performs a handoff and a radio resource management function.

Meanwhile, the wireless access network 210 includes a base station transmitter 212 and a base station controller 214 and supports both synchronous and asynchronous mobile communication systems. In the case of the synchronous mobile communication system, the base station transmitter 212 is a base transceiver station (BTS), the base station controller 214 is a base station controller (BSC), and in the case of an asynchronous mobile communication system, the base station transmitter 212 is an RTS. (Radio Transceiver Subsystem), the base station controller 214 is a Radio Network Controller (RNC). Of course, the wireless access network 210 according to the preferred embodiment of the present invention is not limited to a synchronous or asynchronous CDMA mobile communication network, but may include an access network of a GSM network and a fourth generation mobile communication system currently being standardized.

The base station transmitter 212 is a network endpoint device that performs wired / wireless conversion and wireless signal transmission and reception between the mobile communication terminal 200 and the base station controller 214 and is directly connected to the mobile communication terminal 200. In general, the base station controller 214 controls the base station transmitter 212, and assigns and releases radio channels for the mobile communication terminal 200, and controls the transmission output of the mobile communication terminal 200 and the base station transmitter 212, soft hand. Soft handoff and hard handoff decisions are performed.

The mobile switching center 220 according to the preferred embodiment of the present invention is equipped with a plurality of electronic exchanges to handle basic and additional services, incoming and outgoing call processing of subscribers, checking whether a subscriber is a valid subscriber, location registration procedures and handoffs. Performs procedure processing, interworking with other networks, etc. Here, the other network may include an overseas mobile communication network, and may provide an international roaming service to the mobile communication terminal 200 in association with an overseas mobile communication network. In addition, the mobile switching center 220 supports both IS-95 A / B / C systems, third generation and fourth generation mobile communication networks in synchronous and asynchronous mobile communication networks.

To this end, the mobile switching center 220 includes an access switching subsystem (ASS) that performs distributed call processing, an INS (interconnection network subsystem) that performs centralized call processing, and a centralized function of operation and maintenance (CCS). It may include a subsystem such as a Central Control Subsystem (LOC), a Location Registration Subsystem (LRS) that performs a function of storing and managing information about a mobile subscriber. In addition, the mobile switching center 220 may include an Asynchronous Transfer Mode (ATM) switch (not shown) to transmit data in a cell-based packet manner to increase transmission speed and line efficiency. Can be.

The PSTN 230 according to the preferred embodiment of the present invention connects to the mobile communication terminal 200 via the mobile switching center 220 and the wireless access network 210. Here, the PSTN is an example of another communication network connected to a mobile communication network as a wired telephone switching network used in a general home. In addition to the PSTN, an ISDN (Integrated Services Digital Network) or a mobile communication network of another country for international roaming may be connected.

AC 240 in accordance with a preferred embodiment of the present invention performs authentication for international roaming service and other mobile communication service subscribers using an authentication key and an authentication algorithm, and is located within HLR 250 or mobile switching center 220. You may.

HLR 250 according to a preferred embodiment of the present invention is a database that stores the information of the mobile subscribers personal information of the subscriber, the type of mobile communication service subscribed, the type of mobile communication terminal 200, the location information of the subscriber And the like to the mobile switching center 220. The mobile switching center 220 inquires whether the HLR is a valid subscriber and location information of the subscriber and transmits the information to the mobile communication terminal 200 through the wireless access network 210. Accordingly, when subscribing to an international roaming service, information of an international roaming service subscriber is registered in the HLR 250 of the local mobile communication system.

VLR 260 according to a preferred embodiment of the present invention is a database for temporarily storing information of international roaming services and other mobile communication subscribers in order to reduce the frequent inquiry and updates of the HLR, HLR 250 and mobile switching center 220 ). In addition, the VLR 260 may be located in the mobile switching center 220 to quickly query frequently accessed subscriber information.

3 is a block diagram schematically showing an internal configuration of a mobile communication terminal 200 according to a preferred embodiment of the present invention.

As shown in FIG. 3, the mobile communication terminal 200 according to the preferred embodiment of the present invention includes a memory 302, a key input unit 304, a liquid crystal display unit 306, a microprocessor 308, and a digital signal processing unit ( The DSP may include a digital signal processor (310), a baseband converter 312, a speaker 314, a microphone 316, an RF signal processor 318, an antenna 320, and the like.

The memory 302 according to an exemplary embodiment of the present invention may include a flash memory, a random access memory (RAM), an electrically erasable and programmable read only memory (EEPROM), and the like. The operating system and the call processing software of the mobile communication terminal 200 are stored in a flash memory, and these programs can be loaded and operated in RAM. The EEPROM is a memory that can be electrically erased or restored to store NAM parameters and other storage data such as phone numbers, user names and short messages. In addition, the above-described NAM parameters and other storage data may be stored in a part of the flash memory instead of the EEPROM.

Key input unit 304 according to a preferred embodiment of the present invention is provided with a numeric key for inputting a number, such as a telephone number, and a menu button for selecting a menu or inputting a command, and the liquid crystal display unit 306 is a power supply unit. It displays the overall operation status of the mobile communication terminal, including the level of use, the reception strength of the radio wave, the date and time, and the video screen in the case of using a multimedia service.

The microprocessor 308 according to the preferred embodiment of the present invention controls the mobile communication terminal to select an initial search frequency after initialization, controls to receive SID and NID values in the sink channel in synchronization with the sink channel, and the sink channel. If the SID and NID values received from do not match the SID and NID values set in the NAM, control to change the NAM setting. In addition, the data is transmitted to the baseband converter 312 in order to convert the transmission data into a signal used in the mobile communication network (TX DATA).

The DSP 310 according to an exemplary embodiment of the present invention performs a function of encoding or decoding a signal exchanged with the baseband converter 312 and equalizing the signal to remove noise of a multipath. Digital signal processing processor that performs a function. In addition, the DSP 310 receives the received data RX DATA from the baseband converter 312.

The baseband converter 312 according to the preferred embodiment of the present invention converts signals transmitted and received with the speaker 314, the microphone 316, and the RF signal processor 318 into baseband signals, digital-to-analog conversion, and It performs functions such as analog-to-digital conversion processing. Accordingly, the baseband converter 312 converts the audio data received from the DSP 310 into an audio signal and outputs the audio signal to the speaker 314 or transmits the audio data to the RF signal processor 318 for transmission, and from the microphone 316. The input audio signal is converted into audio data and output to the DSP.

The speaker 314 according to the preferred embodiment of the present invention outputs an acoustic signal as an audible sound, and the microphone 316 receives the voice or sound and converts it into an acoustic signal which is an electrical signal.

The RF signal processor 318 according to an exemplary embodiment of the present invention converts a transmission signal TXIQ into a radio frequency (RF) signal and outputs the RF signal to the antenna 320, or receives an RF signal applied to the antenna 320. (RXIQ) is converted and output to the baseband converter 312, the antenna 320 transmits the RF signal to the air or transmits the RF signal received from the air to the RF signal processor 318.

4 is a flowchart illustrating a method for supporting international roaming service by automatic NAM selection according to a preferred embodiment of the present invention.

As shown in FIG. 4, when power is applied to the mobile communication terminal 200, system information necessary for the operation of the mobile communication terminal 200 is set to initialize the mobile communication terminal 200 (S400). Specifically, when power is supplied to the mobile communication terminal 200, a booting program is executed to check whether the RAM operates normally, read NAM parameters and other system setting information from the EEPROM, store them in the RAM, and store the parameters in the RAM. Initialize the mobile communication terminal 200 by setting hardware.

Here, the NAM is configured from NAM1 to NAM4, and each NAM includes information such as MIN, primary channel, secondary channel, SID, and NID, and any one of NAM1 to NAM4. Is set as the default NAM.

However, according to a preferred embodiment of the present invention, NAM1 includes a domestic MIN and an initial search frequency for domestic services, and NAM2 includes an international roaming MIN and an initial search frequency for international roaming services, so that NAM3 and NAM4 It is preferable to set either one of NAM1 and NAM2 to the NAM of the mobile communication terminal without using.

On the other hand, the information registered in the NAM can be updated when necessary using the Open The Air (OTA) function. Here, the OTA function refers to a function capable of automatically updating by receiving an update value through the wireless access network 210 without manually manipulating the parameters of the mobile communication terminal 200. For example, if a mobile subscriber moves from an area with international roaming service to another area, to update the international roaming MIN and initial discovery frequency registered in NAM2 with the international roaming MIN and initial discovery frequency in that region. The OTA function may be used to automatically update the corresponding parameter value by receiving the update value through the wireless access network 210.

When the mobile communication terminal 200 is initialized, an initial search frequency is selected using the PRL information stored in the mobile communication terminal 200 (S402). When the mobile communication terminal 200 is initialized, the primary channel stored in the NAM is selected to access the mobile communication system, and when the primary channel cannot be received, the secondary channel is selected to search for the initial search frequency. By using the PRL, the frequency channels to be searched are prioritized, registered in a search list, and the frequency channels are sequentially searched according to the priority to select a frequency channel receivable from the wireless access network 210 as an initial search frequency. Here, the PRL may include domestic, international roaming, standard A-Band and standard B-Band frequencies in the PRL search list, and may select one of the aforementioned frequencies as the initial search frequency through the search.

Meanwhile, in order to search for an initial search frequency in a short time, priority of frequency channels to be searched may be determined using a Most Recently Used (MRU) table that separately manages frequency channels to be searched.

When selecting an initial search frequency for accessing a mobile communication system, a pilot channel is searched. Since the pilot channel is synchronized with the sync channel, the pilot channel provides a reference phase for synchronizing the sync channel with the mobile communication terminal 200. In order to find a pilot channel, the mobile communication terminal 200 generates a pseudo noise (PN) code at an initial search frequency and compares the PN code value of a pilot channel received from the wireless access network 210.

Here, the PN code is used for spread spectrum communication that transmits the frequency bandwidth or more of the signal to be transmitted in the CDMA scheme, and distinguishes the base station of the wireless access network 210 by using an offset that is a time difference of the PN code. It plays a role. In the spread spectrum method, since the PN codes of the transmitting side and the receiving side must match, mutual communication is possible, so that the pilot channel is selected when the PN code received on the pilot channel matches the PN code generated by the mobile communication terminal 200. . Since the PN code has almost no correlation at a specific point in time, the largest energy value is calculated when the PN code string generated by the mobile communication terminal 200 and the PN code string received by the pilot channel match. Simply select the pilot channel at that point in time.

When the pilot channel is selected, since the sync channel is synchronized with the reference phase for acquiring the pilot channel as described above, the mobile communication terminal 200 synchronizes with the sync channel (S404). The message received on the sink channel includes information such as SID, NID, PN offset, and System Time, which is a time reference for all call processing.

Accordingly, when the sync channel is synchronized with the mobile communication terminal 200, the SID and NID values of the mobile communication system currently connected from the sync channel can be known. When receiving the SID and the NID value in the sink channel, and compares the SID and NID value included in the NAM configuration of the mobile communication terminal (200) (S406). If the compared SID and NID values do not coincide with each other, the mobile communication terminal 200 selects a NAM in which the SID and NID values of the sink channel are registered to change the NAM of the mobile communication terminal 100 and the mobile communication terminal 200. The initialization procedure is performed again (S408). For example, when the SID and NID values received in the sink channel are identification numbers indicating domestic mobile communication systems and mobile communication networks, the mobile communication terminal 200 is set to NAM2 for receiving international roaming service. After changing the NAM setting to NAM1, the mobile communication terminal 200 is initialized, and when the SID and NID values received in the sink channel are an identification number representing an overseas mobile communication system and a mobile communication network, the mobile communication terminal 200 Is set to NAM1 for receiving a domestic mobile communication service, the mobile communication terminal 200 is initialized after setting the NAM setting to NAM2.

After the above-described NAM setting, the mobile communication terminal 200 is initialized to select an initial search frequency to obtain a pilot channel and tune to the sink channel. The SID and NID values of the sink channel and the NAM setting of the mobile communication terminal 200 are included. The SID and NID values will match. When the compared SID and NID values match, the mobile communication terminal 200 tunes to a paging channel (S410), and sets the mobile communication terminal 200 to an idle state (Idle State) ( S412).

Here, the paging channel is a radio control channel for calling or sending a command to the mobile communication terminal 200. The paging channel is tuned to the mobile communication terminal 200 using a PN offset received from the sink channel, and then a paging channel message. Will be received.

Here, the standby state refers to a state in which the mobile communication terminal 200 prepares to perform a mobile communication service internally after receiving necessary system information in the sink channel, and voice call and short message using international roaming in the standby state. And various mobile communication services such as multimedia messages.

On the other hand, the method for providing an international roaming service by automatic NAM selection according to a preferred embodiment of the present invention is implemented as an application, a computer-readable CD-ROM, Random Access Memory (RAM), Read Only Memory (ROM), It can be stored in a recording medium such as a floppy disk, hard disk, magnetic disk or the like.

Here, the application selects an initial search frequency for accessing the mobile communication system, tunes the mobile communication terminal 200 to the sink channel, checks the SID and NID values received from the sink channel, and then checks the mobile communication terminal 200. If the SID and NID values do not coincide with each other compared to the SID and NID values registered in the NAM of the NAM, the NAM of the mobile terminal 200 is selected by selecting the NAM setting in which the SID and NID values received from the sink channel are registered. Includes the ability to change.

In addition, the application is stored in the memory 302 of the mobile communication terminal 200, and when the mobile communication terminal 200 is initialized, the application may be executed in the microprocessor 308 to perform the functions of the above-described application.

The above description is merely illustrative of the present invention, and those skilled in the art to which the present invention pertains may various modifications without departing from the essential characteristics of the present invention. Accordingly, the embodiments disclosed herein are not intended to limit the present invention but to describe the present invention, and the spirit and scope of the present invention are not limited by these embodiments. It is intended that the scope of the invention be interpreted by the following claims, and that all descriptions within the scope equivalent thereto shall be construed as being included in the scope of the present invention.

As described above, according to the present invention, there is an advantage that a user can automatically select a NAM for roaming without providing a NAM setting for a corresponding region, so that an international roaming service can be provided.

In addition, there is no problem that the mobile terminal does not originate and receive until the NAM setting for the region is manually selected, and the mobile communication service is roamed without roaming without service gap due to NAM setting by automatic NAM selection. There is an effect that can be provided.

1 is an exemplary screen showing a NAM configuration of a mobile communication terminal;

2 is a block diagram showing the configuration of a system supporting international roaming service by automatic NAM selection according to a preferred embodiment of the present invention;

3 is a block diagram showing an internal configuration of a mobile communication terminal according to a preferred embodiment of the present invention;

4 is a flowchart illustrating a method for supporting international roaming service by automatic NAM selection according to a preferred embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

200: mobile communication terminal 210: wireless access network

212: base station transmitter 214: base station controller

220: mobile telephone switchboard 230: PSTN

240: AC 250: HLR

260: VLR 302: memory

304: key input unit 306: liquid crystal display unit

308: microprocessor 310: digital signal processing unit

312: bass band converter 314: speaker

316: microphone 318: RF signal processing unit

320: antenna

Claims (19)

What is claimed is: 1. A method for supporting international roaming service by automatic number assignment module (NAM) selection in a mobile communication system including a wireless access network and a mobile switching center. (a) initializing a mobile communication terminal and selecting an initial search frequency for accessing the mobile communication system; (b) tuning the mobile communication terminal to a Sync Channel from the selected initial search frequency; (c) checking the SID and NID values received through the sink channel and comparing the SID and NID values registered in the NAM of the mobile communication terminal; And (d) If the SID and NID values compared in step (c) do not coincide with each other, select the NAM setting in which the SID and NID values received in the sink channel are registered to change the NAM of the mobile communication terminal. And initializing the mobile communication terminal. Method for supporting international roaming service by automatic NAM selection, comprising a. The method of claim 1, The method, (e) If the SID and NID values compared in the step (c) coincide with each other, the mobile communication terminal and the paging channel are synchronized, and the mobile communication terminal is set to an idle state. step Method for supporting international roaming service by automatic NAM selection, characterized in that it further comprises. The method of claim 1, In step (a), And selecting the initial search frequency by using a preferred roaming list (PRL) stored in the mobile communication terminal. The method of claim 3, wherein The PRL includes frequencies of domestic, international roaming, standard A-Band and standard B-Band in the search list, and the initial search for one of frequencies of domestic, international roaming, standard A-Band and standard B-Band. Method for supporting international roaming service by automatic NAM selection, characterized in that the selection by frequency. The method of claim 3, wherein In the PRL, a priority of frequency channels to be searched is determined and registered in a search list, and the frequency channels are sequentially searched according to the priority to select a frequency channel that can be received from the wireless access network as the initial search frequency. How to support international roaming service by automatic NAM selection. The method of claim 5, The PRL supports an international roaming service by automatic NAM selection, using the Most Recently Used (MRU) table to separately manage the frequency channels to be searched. The method of claim 1, In step (b), (b1) selecting a pilot channel at the selected initial search frequency; And (b2) tuning the mobile communication terminal to a sink channel using the selected pilot channel; Method for supporting international roaming service by automatic NAM selection, comprising a. The method of claim 7, wherein Step (b1), And generating the PN code at the selected initial search frequency and selecting the pilot channel at a point of time matching the PN code received from the pilot channel. The method of claim 7, wherein Step (b2), And the pilot channel is tuned to the sync channel, and when the pilot channel is selected, the mobile communication terminal and the sync channel are automatically tuned to each other. The method of claim 1, The message received in the sync channel includes SID, NID, PN offset and system time information. The method of claim 1, In step (d), If the SID and NID value received in the sink channel is an identification number representing a domestic mobile communication system and a mobile communication network, and the NAM of the mobile communication terminal is set to NAM2 for receiving international roaming service, the mobile communication terminal A method of supporting international roaming service by automatic NAM selection, characterized in that the mobile communication terminal is initialized after changing the NAM setting to NAM1. The method of claim 1, In step (d), If the SID and NID value received in the sink channel is an identification number indicating an overseas mobile communication system and a mobile communication network, and the NAM of the mobile communication terminal is set to NAM1 for receiving domestic mobile communication service, A method for supporting international roaming service by automatic NAM selection, characterized by initializing a mobile communication terminal after changing the NAM setting of the communication terminal to NAM2. The method of claim 1, The information registered in the NAM of the mobile communication terminal is updated using an Open The Air (OTA) function. A computer-readable recording medium recording an application implementing a method for supporting international roaming service by automatic NAM selection in a mobile communication system including a mobile communication terminal, a wireless access network, and a mobile switching center. An SID registered in the NAM of the mobile communication terminal by selecting an initial search frequency for accessing the mobile communication system, tuning the mobile communication terminal to a sink channel, checking the SID and NID values received in the sink channel; When the SID and the NID value do not coincide with each other compared to the NID value, an application for changing the NAM of the mobile communication terminal by selecting a NAM setting in which the SID and the NID value received in the sink channel are registered. A computer-readable recording medium that records the data. The method of claim 16, And the recording medium is a memory of the mobile communication terminal. The computer-readable recording medium recording the application implementing the method for providing the international roaming service by the automatic NAM selection. In the system supporting international roaming service by automatic NAM selection, After selecting an initial search frequency, the NAM in which the SID and NID values received in the sink channel are registered by comparing the SID and NID values received in the sink channel with the SID and NID values registered in the NAM in synchronization with the sink channel. A mobile communication terminal for selecting and changing the NAM setting; A wireless access network for transmitting a message including the SID and NID values to the mobile communication terminal through the sink channel; A mobile telephone exchange station for inquiring whether the subscriber is the international roaming service subscriber in a home location register (HLR) and interworking with an overseas mobile communication network; And An HLR for storing information of the international roaming service subscriber and providing it to the mobile switching center System that supports international roaming service by automatic NAM selection, comprising a. The method of claim 16, An authentication center (AC) for performing authentication for the international roaming service subscriber; And Visitor Location Register (VLR) for temporarily storing information of the international roaming service subscriber and providing it to the mobile switching center The system for supporting international roaming services by automatic NAM selection, characterized in that it further comprises. The method of claim 16, The mobile communication terminal, Control to select the initial search frequency, control to receive SID and NID values in the sink channel in synchronization with the sink channel, and if the received SID and NID values do not match the SID and NID values set in the NAM A microprocessor controlling to change the NAM setting System that supports international roaming service by automatic NAM selection, comprising a. The method of claim 16, The mobile communication terminal may be a PDA (Personal Digital Assistant), a cellular phone, a Personal Communication Service (PCS) phone, a Hand-Held PC (GSM) phone, a Global System for Mobile (GSM) phone, a Wideband CDMA (W-CDMA) phone. And a CDMA-2000 phone and a mobile broadband system (MBS) phone, wherein the system supports international roaming service by automatic NAM selection.