Abstract:
A system and method for detecting a location of a mobile communication terminal. A mobile communication network for communication with the terminal and a cell identifier (ID) of a base station is set. A public land mobile network (PLMN) ID of the network and the cell ID are stored. One or more networks other than the set network are searched for. When the one or more other networks are searched for, the searched one or more other networks are sequentially set. Cell information according to the one or more other networks is searched for. Cell IDs of base stations communicable with the terminal are set. PLMN IDs of the one or more other networks and the cell IDs are stored. A common area between cells set using the stored PLMN and cell IDs is determined. Information about the common area is detected as location information of the terminal.

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) AND CLAIM OF PRIORITY 
     The present application claims the benefit under 35 U.S.C. §119(a) of a Korean Patent Application filed in the Korean Intellectual Property Office on Jul. 31, 2008 and assigned Serial No. 10-2008-0075153, the disclosures of which are incorporated herein by reference. 
     TECHNICAL FIELD OF THE INVENTION 
     The present invention relates generally to a method and system for detecting a location of a mobile communication terminal. 
     BACKGROUND OF THE INVENTION 
     As the use of a mobile communication terminal and a navigation terminal is generalized, various applications and equipments for Location-Based Services (LBS) are being developed and their demands are continuously increasing. 
     In a mobile communication terminal using a mobile communication network, its own location can be detected using cell information of a base station for performing communication at present. In order to detect a location using information of a cell where the mobile communication terminal is located as described above, the mobile communication terminal sets up Public Land Mobile Network (PLMN) and cell Identifiers (IDs) of a mobile communication system. 
       FIG. 1  illustrates a flowchart for an operation for setting PLMN and cell IDs in a conventional Wideband Code Division Multiple Access (WCDMA) mobile communication system. A user identification card such as a Universal Subscriber Identity Module (USIM) is inserted into a mobile communication terminal in step  205 . Then, in step  210 , it is determined whether a PLMN registered according to the user identification card exists. When no registered PLMN exists as the determination result of step  210 , the operation proceeds to step  215  to attempt to select and register another PLMN of a list. Then, in step  220 , it is determined whether the registration of the other PLMN of the list succeeds. When the registration of the other PLMN of the list fails, registration is attempted using all other PLMNs of the list. When the registration of all the other PLMNs of the list fails in step  220 , the operation proceeds to step  225  to search for a possible PLMN and enter a standby state. When a preset specific situation occurs, the operation proceeds to step  210  to re-attempt to register a PLMN. 
     When the PLMN registration succeeds in step  210  or  220 , the operation proceeds to step  230  to determine whether cell information exists. When the cell information exists in step  230 , the operation proceeds to step  245  to select a cell whose information is stored and then proceeds to step  250  to set up the selected cell. 
     When the cell information does not exist in step  230 , the operation proceeds to step  235  to perform a cell initialization process and then proceeds to step  240  to determine whether a selectable cell exists. When the selectable cell exists, the operation proceeds to step  250  to select and set up the cell. When the selectable cell does not exist in step  240 , the operation is in the standby state. 
     By performing the above-described operation, the mobile communication terminal may perform communication by setting up a PLMN and a cell and detect its own location using registered PLMN and cell information. Conventionally, the mobile communication terminal uses PLMN and cell IDs transmitted on a Broadcasting Channel (BCCH) of a base station as information to be stored or utilized to detect its own location. Accordingly, the mobile communication terminal may detect rough location information using the cell information. In this location detection method, location detection is possible in a range of about 3 Kilometers (Km) in the case of a cell of a city center area and in a wider range in the case of a cell of an outer area. 
     A method for detecting a location using cell information of the mobile communication network has a problem in that only rough location information may be detected since a range of the detected location information is wide. Thus, a location detection method capable of acquiring an exact location detection result of a more precise range is needed. 
     SUMMARY OF THE INVENTION 
     To address the above-discussed deficiencies of the prior art, it is a primary object to provide a method and system for exactly detecting location information of a more precise range when a location is detected using information of a cell where a mobile communication terminal is located. 
     According to one aspect of the present invention, a method is provided for detecting a location of a mobile communication terminal, including: setting a mobile communication network for communication with the mobile communication terminal and a cell ID of a base station and storing a PLMN ID of the mobile communication network and the cell ID; searching for one or more mobile communication networks other than the set mobile communication network; sequentially setting, when the one or more other mobile communication networks are searched for, the searched one or more other mobile communication networks, searching for cell information according to the set one or more other mobile communication networks, setting cell IDs of base stations communicable with the mobile communication terminal, and storing PLMN IDs of the set one or more other mobile communication networks and the set cell IDs; and determining a common area between areas of a plurality of cells set using the stored PLMN and cell IDs and detecting information about the common area as location information of the mobile communication terminal. 
     According to another aspect of the present invention, a system is provided for detecting a location of a mobile communication terminal, including: the mobile communication terminal for setting a mobile communication network for communication and a cell ID of a base station, storing a PLMN ID of the mobile communication network and the cell ID, searching for one or more mobile communication networks other than the set mobile communication network, sequentially setting, when the one or more other mobile communication networks are searched for, the searched one or more other mobile communication networks, searching for cell information according to the set one or more other mobile communication networks, setting cell IDs of base stations communicable with the mobile communication terminal, and storing PLMN IDs of the set one or more other mobile communication networks and the set cell IDs; and a location computing unit for receiving the stored PLMN and cell IDs from the mobile communication terminal, determining a common area between areas of a plurality of cells set using the stored PLMN and cell IDs, and detecting information about the common area as location information of the mobile communication terminal. 
     Before undertaking the DETAILED DESCRIPTION OF THE INVENTION below, it may be advantageous to set forth definitions of certain words and phrases used throughout this patent document: the terms “include” and “comprise,” as well as derivatives thereof, mean inclusion without limitation; the term “or,” is inclusive, meaning and/or; the phrases “associated with” and “associated therewith,” as well as derivatives thereof, may mean to include, be included within, interconnect with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, juxtapose, be proximate to, be bound to or with, have, have a property of, or the like; and the term “controller” means any device, system or part thereof that controls at least one operation, such a device may be implemented in hardware, firmware or software, or some combination of at least two of the same. It should be noted that the functionality associated with any particular controller may be centralized or distributed, whether locally or remotely. Definitions for certain words and phrases are provided throughout this patent document, those of ordinary skill in the art should understand that in many, if not most instances, such definitions apply to prior, as well as future uses of such defined words and phrases. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a more complete understanding of the present disclosure and its advantages, reference is now made to the following description taken in conjunction with the accompanying drawings, in which like reference numerals represent like parts: 
         FIG. 1  illustrates a flowchart for a conventional operation for setting PLMN and cell IDs in a mobile communication system; 
         FIG. 2  illustrates an example block diagram of a mobile communication terminal to be used in the present invention; 
         FIG. 3  illustrates a structure of a BCCH; 
         FIG. 4  illustrates an operation concept of detecting a location of the terminal using PLMN and location area code values according to an exemplary embodiment of the present invention; 
         FIG. 5  illustrates an example in which a plurality of PLMN values and a plurality of LAC values are stored in the mobile communication terminal according to an exemplary embodiment of the present invention; 
         FIG. 6  illustrates a flowchart for an operation for storing PLMN and cell IDs according to an exemplary embodiment of the present invention; 
         FIG. 7  illustrates a structure of a map database according to an exemplary embodiment of the present invention; 
         FIG. 8  illustrates a block diagram for an internal structure of the terminal for location detection according to an exemplary embodiment of the present invention; and 
         FIG. 9  illustrates a block diagram for an external server separately implemented for the location detection structure according to an exemplary embodiment of the present invention. 
     
    
    
     Throughout the drawings, the same drawing reference numerals will be understood to refer to the same elements, features and structures. 
     DETAILED DESCRIPTION OF THE INVENTION 
       FIGS. 2 through 9 , discussed below, and the various embodiments used to describe the principles of the present disclosure in this patent document are by way of illustration only and should not be construed in any way to limit the scope of the disclosure. Those skilled in the art will understand that the principles of the present disclosure may be implemented in any suitably arranged wireless communications system. 
     The present invention provides a technology for detecting a location using every information of a corresponding cell, intersected with a plurality of PLMNS, where a mobile communication terminal is located by searching for the PLMNs whose information is included in a BCCH and utilizing and storing unregistered PLMN and cell IDs except registered PLMN and cell IDs when the location is detected using the information of the cell where the mobile communication terminal is located. 
       FIG. 2  illustrates an example block diagram of a mobile communication terminal to be used in the present invention. A structure of a mobile communication terminal  100  to which the present invention is applied includes a Global Positioning System (GPS) module  110 , a controller  120 , a mobile communicator  130 , a memory  140 , a key input unit  150 , and a display  160 . 
     The controller  120  controls an overall operation of the mobile communication terminal  100 . 
     Under control of the controller  120 , the display  160  displays various image information and data and images received from a base station  200  or stored in the memory  140  on a screen. 
     The key input unit  150  includes * and # keys and a plurality of function keys of Menu, Select, Call, Delete, Power/End, Volume, Capture, and the like, corresponding to various functions of the mobile communication terminal, and provides the controller  120  with key input data corresponding to a key pressed by a user. The key input unit  150  includes alphanumeric keys to which numbers of ‘0’ through ‘9’ and Korean or English letters are allocated. 
     Under the control of the controller  120 , the GPS module  110  receives a GPS signal. The GPS module  110  computes a current location using the received GPS signal, and computes various data required for performing a navigation function, by interfacing with the controller  120  and the memory  140 . 
     Under the control of the controller  120 , the mobile communicator  130  performs an operation and signal processing required for mobile communication. The mobile communicator  130  transmits a radio signal to, and receives a radio signal from, a mobile communication base station  200  via an antenna. The mobile communicator  130  modulates a transmission radio signal input from the controller  120  through a baseband processor and transmits the radio signal via the antenna. Also, the mobile communicator  130  demodulates a radio signal received via the antenna and provides the radio signal to the controller  120  through the baseband processor. The baseband processor processes a baseband signal transmitted/received from the controller  120 . The mobile communicator  130  always changes a state on downlink/uplink with the base station  200 . In this case, the state is controlled by reporting the state to the controller  120 . The controller  120  holds information about the base station  200  connected to the mobile communicator  130 , that is, a base station of a service cell, and information about a neighboring base station. The information is a cell ID corresponding to a base station ID. A service cell ID and a neighboring cell ID are received by the base station of the service cell. Hereinafter, in an exemplary embodiment of the present invention, a cell having a service area including a point at which the current mobile communication terminal  100  is located is referred to as the service cell. 
     The cell ID is allocated as a result of cell planning to control the coverage of each region in a mobile communication system and is designed to support the entire city and country. A service area of one cell has a communication radius of, for example, about 1˜2 Km in a city center area or about 3˜5 Km in an outer area. 
       FIG. 3  illustrates a structure of a BCCH. The BCCH includes a Mobile Country Code (MCC), a Mobile Network Code (MNC), a Location Area Code (LAC), and a Routing Area Code (RAC). The MCC is a country code that can have a value such as, for example, “England 234”. The MNC is a network code that can have a value such as, for example, “Vodafone 15”. The MCC and MNC are determined according to a PLMN. The LAC is a cell ID of a base station. A LAC value is set differently according to a base station. 
       FIG. 4  illustrates an operation concept of detecting a location of the terminal using a plurality of PLMN values and a plurality of LAC values according to an exemplary embodiment of the present invention. As illustrated in  FIG. 4 , when the terminal is located in a cell corresponding to “LAC 001” of a first PLMN (for example, SK Telecom (SKT) communication network), a conventional method can detect only location information indicating a range of the cell of “LAC 001” of the first PLMN. However, since the location information is detected using all of a second PLMN (for example, Korea Telecom Freetel (KTF) communication network), a cell where the terminal is located in the second PLMN, a third PLMN (for example, LG Telecom (LGT) communication network), and a cell where the terminal is located in the third PLMN according to a feature of the present invention, the location information of the current mobile communication terminal can be detected by computing location information of an area intersected with the three cells. 
     For example, as illustrated in  FIG. 4 , the current mobile communication terminal is simultaneously located in the cell corresponding to “LAC 001”  405  of the first PLMN, in the cell corresponding to “LAC 001”  406  of the second PLMN, and in the cell corresponding to “LAC 001”  407  of the third PLMN. A location information result having a range indicated by reference numeral  401  is acquired in the conventional method, but an exact location information result having a range indicated by reference numeral  402  is acquired using a plurality of PLMN values and a plurality of LAC values according to an exemplary embodiment of the present invention. 
       FIG. 5  illustrates an example in which a plurality of PLMN values and a plurality of LAC values are stored in the mobile communication terminal according to an exemplary embodiment of the present invention. A mobile communication terminal conventionally stores one PLMN value and one LAC value. However, as illustrated in  FIG. 5 , the mobile communication terminal stores a plurality of PLMN information elements capable of being set by the mobile communication terminal and cell information elements (LACs) corresponding to the PLMNs according to an exemplary embodiment of the present invention. The information of PLMNs and cells can be searched for and set by the mobile communication terminal. 
       FIG. 6  illustrates a flowchart for an operation for storing PLMN and cell IDs according to an exemplary embodiment of the present invention. In step  605 , a cell is set up by performing a process for setting existing PLMN and cell IDs. In step  610 , a neighboring PLMN other than a registered PLMN is additionally searched for. In step  615 , it is determined whether the searched PLMN exists. When no searched PLMN exist in step  615 , a PLMN is periodically searched for in step  610 . 
     When the searched PLMN exists in step  615 , the operation proceeds to step  620  to select the searched PLMN. In step  625 , a cell initialization search process is performed for a cell of the selected PLMN. In step  630 , it is determined whether a selectable cell of an area where the current mobile communication terminal is located exists. When no selectable cell exists in step  630 , the cell initialization search process is re-performed in step  625 . When the selectable cell exists as n step  630 , information about the selected PLMN and cell is stored in step  635 . 
     When a plurality of PLMNs is searched for in step  610 , the above-described operations, whose number corresponds to the number of searched PLMNs, are performed so that information about the plurality of PLMNs and a plurality of cells thereof is stored. 
       FIG. 7  illustrates a structure of a map database according to an exemplary embodiment of the present invention. The map database according to the exemplary embodiment of the present invention includes an index field, a point of interest (POI) name field, a POI category field, a location field, a telephone number field, a link ID field, an attribute field, and a type list field, and further includes a PLMN/LAC field according to a feature of the present invention. Location information of each POI can be computed using a PLMN/LAC field for each POI. 
       FIG. 8  illustrates a block diagram for an internal structure of the terminal for location detection according to an exemplary embodiment of the present invention.  FIG. 9  illustrates a block diagram for an external server separately implemented for the location detection structure according to an exemplary embodiment of the present invention. As illustrated in  FIG. 8 , the location detection structure according to the exemplary embodiment of the present invention includes a location computing unit  800  having a PLMN/cell ID database and a map database inside the terminal  100 , thereby exactly measuring and detecting location information of the terminal  100  to which a plurality of PLMN values and a plurality of LAC values are input. As illustrated in  FIG. 9 , the external server includes a location computing unit  900  that can have a PLMN/cell ID database and a map database, receive PLMN and LAC values from the terminal  100 , and measure and output terminal location information. 
     According to the above-described exemplary embodiments of the present invention, a location detection method and apparatus of a mobile communication terminal can be operated and configured. 
     According to an exemplary embodiment of the present invention, a mobile communication terminal can acquire its own location information in a more precise range than that of a conventional technology by searching for a plurality of PLMNs whose information is included in a BCCH and utilizing and storing unregistered PLMN and cell IDs except registered PLMN and cell IDs, when a location is detected using information about a cell where the mobile communication terminal is located. 
     Although the present disclosure has been described with an exemplary embodiment, various changes and modifications may be suggested to one skilled in the art. It is intended that the present disclosure encompass such changes and modifications as fall within the scope of the appended claims.