KR20100137158A - Method and communication system for scanning base station - Google Patents

Abstract

PURPOSE: A method for scanning a base station and a communication system performing the same are provided to enable a portable terminal to obtain a base station when performing a roaming between Wi-Max network. CONSTITUTION: A service provider server(330) receives roaming area information. A service business owner server searches roaming object base station information corresponding to roaming area information from a business owner sharing DB(340). The service business owner transmits the searched roaming target base station information to a portable terminal(300). The portable terminal stores roaming target base station information to a connection management table. The portable terminal scans the base station by using connection management table.

Description

Base station scanning method and communication system performing same {METHOD AND COMMUNICATION SYSTEM FOR SCANNING BASE STATION}

The present invention relates to a method for scanning a base station and a communication system for performing base station scanning, and more particularly, to a method for scanning a base station when roaming on a WiMAX network and a communication system for performing the same.

Worldwide Interoperability for Microwave Access (WIMAX) is a communications technology that can transmit and receive data over long distances in a variety of ways, from point-to-point connections to fully portable access. As standards such as Release 1.5 and 802.16m are proposed, WiMAX technology is expected to be serviced by more countries and service providers. In line with this trend, the WiMAX standardization group has launched the Global Roaming Working Group (GRWG) to standardize roaming between WiMAX networks. In addition, each service provider is promoting WiMAX by establishing a WIMAX Global Roaming Belt to support each other's roaming.

However, because WiMAX profiles are set differently for each country such as Korea (2.3GHz / 8.75MHz), US / Japan (2.5GHz / 5 ~ 10MHz), Europe (3.5GHz / 10MHz), it is difficult to spread roaming between service providers. There is a problem.

Manufacturers of handhelds are manufacturing them to support all WiMAX profiles on the base band and RF receiver side. However, when the mobile terminal is located on the WiMAX network, roaming is difficult because there is no standardization on how to load profile information of the corresponding country and service provider for roaming.

In order to solve this problem, when roaming a network, the mobile terminal scans all base stations located in the moved network and communicates with the base stations. This method is described with reference to FIG.

1 is a flowchart illustrating a method of scanning a base station according to the prior art.

Referring to FIG. 1, when a user turns off and on a portable terminal to perform roaming between networks, the portable terminal performs a booting mode in step 110. In the boot mode, the portable terminal powers all configurations and performs initialization. Next, in step 120, the mobile terminal scans a Most Recently Used (MRU) table to search for a base station that can communicate. The MRU table lists base station information to which the mobile terminal has been recently connected. The base station information includes a base station identifier, a service provider identifier for managing the base station, a serviceable frequency band, and a used frequency band.

Next, in step 130, the mobile terminal determines whether there is neighbor base station information located in the vicinity of the mobile terminal among the base station information included in the MRU table. If there is neighbor base station information, the mobile terminal connects to the base station corresponding to the neighbor base station information identified in step 140 to perform a communication function.

On the other hand, if the neighbor base station information does not exist, the portable terminal scans the OMA (Open Mobile Alliance) -DM (Device Management) table in step 150. The OMA-DM table includes all WiMAX profiles and service provider information that can be supported by the mobile terminal. Here, the service provider information includes information such as a service provider identifier, an ID of a base station managed by the service provider, and a frequency band available for service. In operation 160, the portable terminal determines whether neighboring base station information exists. If there is neighbor base station information, the mobile terminal connects to the base station corresponding to the neighbor base station information identified in step 140 to perform a communication function.

However, if the neighboring base station information does not exist in step 160, the portable terminal scans the base station information of all the base stations located around the portable terminal in step 170. The mobile terminal performs a communication function by connecting to a base station corresponding to a set condition among the base station information scanned in step 140. Conditions set here relate to signal strength and service provider selection. Therefore, the portable terminal must have a strength of a signal transmitted at least a certain intensity, and can perform a communication function by forming a channel with a base station managed by a service provider determined to provide a communication service to the portable terminal.

However, as service providers increase, the number of OMA-DM tables that a mobile terminal will scan when roaming increases. The OMA-DM table will be described in detail with reference to FIG. 2.

2 is a diagram illustrating an OMA-DM table according to the prior art.

Referring to FIG. 2, the OMA-DM table includes detailed information such as base station information for each service provider. The size of information stored in each service provider occupies a memory, but it generally takes more than a few tens of bytes. As shown in FIG. 2, service provider-specific information includes a base station identifier 210, information about a frequency band 220, information about a serviceable frequency band 230, and the like. As the service provider-specific information stored in the memory increases, it takes a long time to scan the OMA-DM table in the mobile terminal. In addition, since the size of the memory is limited, there is a problem that cannot store all roamable service provider information. In addition, when the size of the memory increases, there is a problem in that the price of the portable terminal is increased.

In order to solve the above problems, the present invention proposes a method of scanning a base station when roaming and a communication system performing the same.

In order to achieve the above object, a base station scanning method according to an embodiment of the present invention comprises the steps of: transmitting the input roaming area information to the service provider server; The service provider server transmitting the roaming target base station information corresponding to the roaming area information to the mobile terminal; The mobile terminal storing the roaming target base station information in a connection management table; The mobile terminal includes scanning a base station through the connection management table.

In addition, the communication system according to an embodiment of the present invention to achieve the above object is interworking between service providers, the service provider sharing database for storing at least one roaming target base station information for each service provider; A service provider server that retrieves roaming target base station information corresponding to the roaming area information from the service provider sharing database and transmits the information to the mobile terminal when roaming area information is input; The mobile terminal stores the roaming target base station information in a connection management table and scans the base station using the connection management table.

According to the present invention, when roaming is performed between WiMAX networks, the mobile terminal can quickly acquire a base station. In addition, the memory can be used efficiently, thereby making it possible to produce low-cost portable terminals.

The term 'portable terminal' refers to an information processing device capable of transmitting and receiving data through a communication function with an external terminal, and may be a mobile phone, a personal digital assistant (PDA), a portable wireless router, or the like.

The recent connection table refers to a table storing at least one base station information corresponding to a connected base station before the portable terminal is powered off. The recent connection table is updated each time the base station is connected.

The connection management table is a table that stores base station information on a service provider providing a communication service and a base station managed by the service provider to perform a communication function on the mobile terminal.

The roaming table is a table storing base station information extracted from the connection management table according to current location information of the mobile terminal. The roaming table is deleted when the portable terminal is turned off and is created when the portable terminal is turned on.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that in the following description, only parts necessary for understanding the operation according to the present invention will be described, and descriptions of other parts will be omitted so as not to distract from the gist of the present invention.

3 is a flowchart illustrating a method of updating base station information between communication systems according to an embodiment of the present invention.

Referring to FIG. 3, a communication system performing a communication function in a WiMAX network includes a service provider server 330 connected through a mobile terminal 300, a gateway (GW; GateWay 310), a network 320, and a service provider. Database 340 (commercial shared DB), OMA-DM server 350 is composed of.

In order to use the roaming service due to the movement of the mobile terminal 300, the user connects to the service provider server 330 connected to the network 320 through the gateway 310 through the mobile terminal 300. The mobile terminal 300 displays a web page transmitted from the service provider server 330. When the area information to roam is input from the user, the portable terminal 300 transmits the roaming area information input to the service provider server 330 in step ①. The roaming area information includes information about a location of a location where the mobile terminal 300 will move, and a service provider that will service a communication function. In this case, the user may select at least one region as roaming region information, and may select at least both a country of the region and at least one service provider.

The service provider server 330 searches for roaming target base station information including roaming area information in the service provider sharing database 340 (Global WIMAX Database) in step ②. The operator sharing database 340 may link with each service provider and store profile information for each country and service provider. The profile information for each service provider stores detailed information on base stations managed by each service provider and information on frequency bands available for service. Detailed information about the base station is called roaming target base station information, and includes information on an identifier of the base station, an identifier of a service provider managing the base station, a serviceable frequency band, a location of the base station, and a size of an area managed by the base station.

Next, the service provider server 330 transmits the roaming target base station information retrieved from the operator sharing database 340 to the OMA-DM server 350 connected with the service provider server 330 in step ③. In a communication environment capable of communicating through a WiMAX network, the mobile terminal 300 communicates with the service provider server 330 through the OMA-DM server 350. Here, the OMA-DM server 350 is a server that provides mobile services that are compatible with each other regardless of country, service provider, mobile terminal, or communication method.

Next, the OMA-DM server 350 transmits roaming target base station information to the mobile terminal 300 in step ④. Then, the mobile terminal 300 stores the received roaming target base station information in the connection management table. The mobile terminal 300 updates the roaming table through base station information stored in the connection management table when roaming. The mobile terminal 300 may scan the base station by using the base station information including the roaming table.

4 is a diagram illustrating a signal flow between communication systems for updating base station information according to an embodiment of the present invention.

Referring to FIG. 4, the mobile terminal 300, the service provider server 330, the OMA-DM server 350, and the service provider sharing database 340 are connected through a network in step 410. In order to receive a roaming service, a user inputs a roaming area and roaming area information about a service provider through a web page of the service provider server 330. Then, the mobile terminal 300 transmits the roaming area information input in step 420 to the service provider server 330.

The service provider server 330 retrieves roaming target base station information corresponding to the roaming area information received in step 430 from the operator sharing database 340. The roaming area information input by the user includes information on an area to which the mobile terminal 300 will move. Therefore, the service provider server 330 may search for base station information located in a region input by the user among base station information stored for each service provider stored in the service provider sharing database 340. The base station information stored in the operator sharing database 340 is called roaming target base station information. Roaming target base station information includes the identifier of the base station, location information indicating the location of the base station by longitude, latitude, altitude, etc., an identifier of a service provider managing the base station, area information on a serviceable area, and a frequency on a frequency band that can be serviced. Band information and the like.

If the roaming target base station information is found, the service provider server 330 calls the roaming target base station information retrieved from the operator sharing database 340 in step 440. In operation 450, the service provider server 330 transmits roaming target base station information to the OMA-DM server 350. The OMA-DM server 350 transmits roaming target base station information to the mobile terminal 300 in step 460. Then, the mobile terminal 300 updates the connection management table by using the roaming target base station information received in step 470. At this time, the mobile terminal 300 classifies and stores roaming target base station information for each service provider. Next, the portable terminal 300 scans the base station in step 480. The process of performing the base station scanning will be described later with reference to FIGS. 8 to 10.

A configuration of a mobile terminal 300 scanning a base station when roaming will be described with reference to FIG. 5.

5 is a diagram schematically illustrating a configuration of a portable terminal according to an embodiment of the present invention.

Referring to FIG. 5, the portable terminal 300 includes a communication unit 510, an input unit 520, a controller 530, a location checker 540, and a memory 550.

The communication unit 510 performs a communication function between the mobile terminal 300 and the base station. In addition, the communication unit 510 performs a communication function with the service provider server 330 through a network. The communication unit 510 is connected to the service provider server 330 under the control of the controller 530, and transmits roaming area information input from the user to the service provider server 330. The roaming area information may be information about an area to which the at least one portable terminal 300 will move and a service provider that provides at least one service. The communication unit 510 transmits roaming target base station information transmitted from the OMA-DM server 350 to the control unit 530.

The input unit 520 transmits a signal input in connection with the function control of the portable terminal 300 such as numeric and text information input from a user and setting of various functions, to the controller 530. The input unit 520 may be formed of a touch screen or a keypad. The input unit 520 may include a text key composed of numbers and letters, a function key for selecting a function, a soft key, and the like. Here, the input unit 520 transmits roaming information input by the user to the control unit 530.

The controller 530 controls the operation and status of the overall configuration of the mobile terminal 300. Herein, the controller 530 may transmit the roaming area information input from the user through the communication unit 510 to the service provider server 330. In more detail, the user accesses the web page of the service provider server 330 by using the mobile terminal 300 or the computer in order to use the roaming service. When accessing the web page of the service provider server 330 through a computer, the user must input not only the region information to roam but also the identifier of the mobile terminal 300 to receive the roaming target base station information. The identifier of the mobile terminal 300 may be a telephone number, and the service provider server 330 searches for roaming target base station information corresponding to the input roaming information. Next, the service provider server 330 may transmit the roaming target base station information searched to the mobile terminal 300 corresponding to the input identifier. Herein, it is assumed that the mobile terminal 300 is connected to the service provider server 330.

The controller 530 controls the communication unit 510 to connect with the service provider server 330 and displays a web page transmitted from the service provider server 330 on the display unit. Next, the user inputs local information to roam through the input unit 520. Then, the controller 530 transmits the input roaming area information to the service provider server 330. Herein, only the region is input as the roaming region information, but is not limited thereto. That is, the service provider may be selected as the roaming region information, or the region and the service provider may be selected together.

The controller 530 may store roaming target base station information transmitted from the connected service provider server 330 in the memory 550. When roaming target base station information is received through the communication unit 510, the controller 530 stores the received roaming target base station information in the memory 550. At this time, the controller 530 classifies the roaming target base station information for each service provider and stores it in the connection management table. The roaming target base station information is transmitted through the service provider server 330, and an identifier for identifying the service provider is also transmitted. Accordingly, the controller 530 may classify and store roaming target base station information using a service provider identifier.

In order to perform roaming between networks, the user turns off and then turns on the portable terminal 300. When the power is turned on, the controller 530 starts booting to supply and initialize power to all components of the mobile terminal 300. In addition, the controller 530 controls the location checker 540 to obtain location information of the current mobile terminal 300. Next, the controller 530 extracts roaming target base station information including location information obtained from the connection management table stored in the memory 550. The controller 530 generates the extracted at least one roaming target base station information as a roaming table.

Next, the control unit 530 scans the base station located in the vicinity to connect with the base station. To this end, the controller 530 checks a recent connection table stored in the memory 550. The recent connection table lists base station information for the connected base station until the portable terminal 300 is powered off. The controller 530 scans the base station corresponding to the base station information of the recent connection table. If there is a base station that can communicate as a result of scanning, the controller 530 controls the communication unit 510 to form a channel with the base station to perform a communication function.

However, if there is no communication base station, the controller 530 checks the roaming table. The roaming table is a table generated by extracting at least one roaming target base station information including location information of the current mobile terminal 300 from the roaming target base station information stored in the connection management table. The controller 530 scans a base station corresponding to roaming target base station information of the roaming table. If there is a base station that can communicate as a result of scanning, the controller 530 controls the communication unit 510 to form a channel with the base station to perform a communication function.

On the other hand, if there is no base station that can communicate, the controller 530 checks the connection management table. The connection management table is transmitted through the service provider server 330 and stores the roaming target base station information retrieved from the operator sharing database 340 according to the roaming area information input by the user in advance. The controller 530 scans base stations corresponding to all roaming target base station information included in the connection management table. If there is a base station that can communicate as a result of scanning, the controller 530 controls the communication unit 510 to form a channel with the base station to perform a communication function. If there is no base station connectable as a result of the scanning, the controller 530 controls the communication unit 510 to scan all frequency bands and search for all base stations located in the vicinity.

According to the present invention, the control unit 530 scans the base station in order of at least one base station information included in the recent connection table, at least one base station information included in the roaming table, and base station information included in the connection management table. Accordingly, the controller 530 can shorten the time taken to scan the base station.

The location checker 540 checks the current location of the mobile terminal 300 under the control of the controller 530. To this end, the positioning unit 540 may be configured as a global positioning system (GPS) receiver. The GPS receiver receives location information from the GPS satellites.

The memory 550 may store an application program related to a function that may be performed in the portable terminal 300 and data generated while performing the function. The memory 550 includes a read only memory (ROM) 560 and a random access memory (RAM) 570.

The ROM 560 is a nonvolatile memory device in which stored information is maintained even when power is not supplied. Thus, ROM 560 is used to permanently store application programs and data. The RAM 570 is a device capable of reading stored data and storing other data. When the power supply is interrupted, the stored data is deleted. Thus, RAM 570 is used to temporarily store data. Here, data stored in the ROM 560 and the RAM 570 will be described with reference to FIG. 6.

6 is a diagram illustrating a structure of a memory according to an embodiment of the present invention.

Referring to FIG. 6, the memory 550 includes a ROM 560 and a RAM 570. The ROM 560 includes a recent connection table (hereinafter, an MRU table; most recently used table 610) and a connection management table. (Hereinafter referred to as OMA-DM table; Open Mobile Alliance- Device Management 620). The roaming table 630 is stored in the RAM 570.

The MRU table 610 is a table that stores at least one base station information of a base station connected before the portable terminal 300 is powered off. The MRU table 610 includes information such as an identifier of the base station, a service provider identifier managing the base station, location information of the base station, a frequency band available for the service, and the like.

The OMA-DM table 620 stores at least one roaming target base station information transmitted from the service provider server 330 through the OMA-DM server 350. The OMA-DM table 620 includes information on service providers that can provide services to the mobile terminal 300, and information on roaming target base stations managed by each service provider. Roaming target base station information is described with reference to FIG.

7 is a diagram illustrating a structure of a connection management table according to an embodiment of the present invention.

Referring to FIG. 7, the OMA-DM table 620 is classified by service providers and stores at least one roaming target base station information for each service provider. The roaming target base station information includes location information 710 indicating a location of the base station, an identifier 720 of the base station, an identifier of a service provider managing the base station, available frequency bandwidth 730, available frequency band 740, and the like. It includes.

The roaming table 630 extracts only at least one roaming target base station information including location information corresponding to the location of the current mobile terminal 300 from among at least one roaming target base station information included in the OMA-DM table 620. It is a list. The roaming table 630 is created in the RAM 570 when the portable terminal 300 is booted and deleted when the portable terminal 300 is powered off.

A method of scanning a base station in the mobile terminal 300 having such a configuration will be described with reference to FIG. 8.

8 is a diagram illustrating a base station scanning method according to an embodiment of the present invention.

Referring to FIG. 8, a user turns off and then turns on the portable terminal 300 to use a roaming service. In operation 810, the controller 530 performs a boot mode. At this time, the control unit 530 supplies power to all components of the mobile terminal 300 and initializes them.

Next, the controller 530 determines whether location information of the location where the mobile terminal 300 is currently located is acquired through the location checker 540 in step 820. If the current location information is obtained, the controller 530 extracts roaming target base station information according to the current location information from the OMA-DM table 620 stored in the ROM 560 and generates the roaming table 630. At this time, the roaming table 630 is stored in the RAM 570 under the control of the controller 530. Next, the controller 530 scans the base station according to the location information in step 840. Operation 840 will be described later with reference to FIG. 9. The controller 530 generates a channel with the base station scanned in step 850 to perform a communication function. Although not shown in the drawing, the controller 530 updates the base station information corresponding to the connected base station in the recent connection table.

On the other hand, if the current location information is not obtained, the controller 530 scans the base station that can communicate in step 860. Operation 860 will be described later with reference to FIG. 10. In addition, the controller 530 generates a channel with the base station scanned in step 850 to perform a communication function. Although not shown in the drawing, the controller 530 updates base station information corresponding to the connected base station to the MRU table 610.

A base station scanning process based on location information will be described in detail with reference to FIG. 9.

9 is a flowchart illustrating a base station connection method according to an embodiment of the present invention.

Referring to FIG. 9, when location information on the current location of the mobile terminal 300 is obtained, the controller 530 checks the MRU table 610 stored in the ROM 560 in step 910. The MRU table 610 stores at least one base station information on a base station connected to the mobile terminal 300 until recently. Next, the controller 530 scans the base stations corresponding to the base station information stored in the MRU table 610.

As a result of scanning, the controller 530 determines whether there is a base station that can communicate in step 920. If the base station according to the base station information of the MRU table 610 is not scanned, the controller 530 checks the roaming table 630 stored in the RAM 570 in step 930. The roaming table 630 lists roaming target base station information extracted from the OMA-DM table 620, and among the at least one roaming target base station information stored in the OMA-DM table 620, the current state of the mobile terminal 300. Roaming target base station information including location information is extracted and generated.

As a result of scanning, the controller 530 determines whether there is a base station that can communicate in step 940. If the base station according to the base station information of the roaming table 630 is not scanned, the controller 530 checks the OMA-DM table 620 stored in the ROM 560 in step 950. The OMA-DM table 620 lists roaming corresponding base station information transmitted from the service provider server 330 through the OMA-DM server 350. The roaming target base station information includes information such as an ID of a base station managed for each service provider, location information of the base station, a frequency band available for service, and the like. The controller 530 scans all base stations corresponding to roaming target base station information stored in the OMA-DM table 620.

As a result of scanning, the controller 530 determines whether there is a base station that can communicate in step 960. If the base station according to the roaming target base station information of the OMA-DM table 620 is not scanned, the controller 530 scans all frequency bands in step 970 to search for all base stations located around the portable terminal 300. . In operation 980, the controller 530 connects with the base station having the strongest received signal according to the scanning result. Although not shown in the drawing, the controller 530 updates base station information corresponding to the connected base station to the MRU table 610.

In the above, a method of scanning a base station when the location information of the current mobile terminal 300 is confirmed has been described. Next, a method of scanning a base station when the location information of the mobile terminal 300 cannot be confirmed will be described with reference to FIG. 10.

10 is a flowchart illustrating a base station scanning method according to another embodiment of the present invention.

Referring to FIG. 10, if location information on the current location of the mobile terminal 300 is not obtained, the controller 530 checks the MRU table 610 stored in the ROM 560 in step 1010. The MRU table 610 stores at least one base station information on a base station connected to the mobile terminal 300 until recently. Next, the controller 530 scans the base stations corresponding to the base station information stored in the MRU table 610.

As a result of scanning, the controller 530 determines whether there is a base station that can communicate in step 1020. If there is no base station that can communicate, the controller 530 checks the OMA-DM table 620 stored in the ROM 560 in step 1030. The OMA-DM table 620 lists roaming corresponding base station information transmitted from the service provider server 330 through the OMA-DM server 350. The roaming target base station information includes information such as an ID of a base station managed for each service provider, location information of the base station, a frequency band available for service, and the like. The controller 530 scans all base stations corresponding to roaming target base station information stored in the OMA-DM table 620.

As a result of scanning, the controller 530 determines whether there is a base station that can communicate in step 1040. If there is no base station that can communicate, the controller 530 scans all base stations located around the portable terminal 300 in step 1050. In operation 1060, the controller 530 connects with the base station having the strongest received signal according to the scanning result. Next, the controller 530 performs a communication function through the connected base station. Although not shown in the drawing, the controller 530 updates base station information corresponding to the connected base station to the MRU table 610.

In the above embodiments of the present invention disclosed in the specification and drawings are merely described specific examples to easily explain the technical contents of the present invention and help the understanding of the present invention, and are not intended to limit the scope of the present invention. . It will be apparent to those skilled in the art that other modifications based on the technical idea of the present invention can be carried out in addition to the embodiments disclosed herein.

1 is a flow chart illustrating a method for scanning a base station according to the prior art.

2 shows an OMA-DM table according to the prior art;

3 is a flowchart illustrating a method of updating base station information between communication systems according to an embodiment of the present invention.

4 is a diagram illustrating a signal flow between communication systems for updating base station information according to an embodiment of the present invention.

5 is a diagram schematically illustrating a configuration of a portable terminal according to an embodiment of the present invention.

6 illustrates a structure of a memory according to an embodiment of the present invention.

7 is a diagram illustrating the structure of a connection management table according to an embodiment of the present invention.

8 illustrates a base station scanning method according to an embodiment of the present invention.

9 is a flowchart illustrating a base station connection method according to an embodiment of the present invention.

10 is a flowchart illustrating a base station scanning method according to another embodiment of the present invention.

Claims (7)

A base station scanning method of a communication system for roaming between WiMAX networks, Transmitting input roaming area information to a service provider server; The service provider server transmitting the roaming target base station information corresponding to the roaming area information to the mobile terminal; The mobile terminal storing the roaming target base station information in a connection management table; And the mobile terminal scans a base station through the connection management table. The method of claim 1, Acquiring location information corresponding to a location of a mobile terminal at boot time; Retrieving roaming target base station information including the location information from the connection management table; Generating roaming target base station information as a roaming table; And performing a communication function with the base station scanned using the generated roaming table. The method of claim 2, Scanning the base station using a recent connection table including base station information of the base station connected before the portable terminal is powered off; Scanning a base station using roaming target base station information of the roaming table when the base station according to the base station information of the recent connection table is not scanned; And if the base station according to the roaming target base station information is not scanned, scanning the base station by using all roaming target base station information of the connection management table. The method of claim 1, wherein the roaming target base station information is And at least one of location information of a base station, an identifier of the base station, an available frequency bandwidth, and area information of a serviceable area. A service provider sharing database capable of interworking between service providers, and storing at least one roaming target base station information for each service provider; A service provider server that retrieves roaming target base station information corresponding to the roaming area information from the service provider sharing database and transmits the information to the mobile terminal when roaming area information is input; And a mobile terminal configured to store the roaming target base station information in a connection management table and scan a base station using the connection management table. The method of claim 5, wherein the portable terminal A communication unit receiving the roaming target base station information; A memory configured to store a recent connection table including base station information of a base station connected before the portable terminal is turned off, and the connection management table including the roaming target base station information; A positioning unit to check current location information of the portable terminal; When booting, a control unit for searching the at least one roaming target base station information corresponding to the location information in the connection management table to generate a roaming table, and performs a communication function with the base station scanned using the generated roaming table A base station scanning communication system comprising. The method of claim 5, wherein the control unit If the base station corresponding to the base station information of the recent connection table is scanned, if the base station is not scanned, if the base station corresponding to roaming target base station information of the roaming table is scanned, if the base station according to the roaming target base station information is not scanned, And a base station corresponding to all roaming target base station information of the connection management table.

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