Abstract:
A method for constructing a zone database for providing home zone services to the subscribers of a mobile communications system, comprises the steps of dividing a service area into a plurality of home service zones; simulating the communication coverage of the base stations for each of the home service zones; detecting the pilot signal strengths of the base stations; and, selecting a given number of the base stations in the order of pilot signal strength as the home zone.

Description:
CLAIM OF PRIORITY 
     This application makes reference to and claims all benefits accruing under 35 U.S.C. Section 119 from an application for APPARATUS FOR CONSTRUCTING A ZONE DATA BASE FOR HOME ZONE SERVICE AND METHOD THEREFORE filed earlier in the Korean Industrial Property Office on Sep. 13, 1999 and there duly assigned Ser. No. 39029/1999. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an apparatus and method for constructing a zone database to provide home zone services to the subscribers of a mobile communications system. 
     2. Description of the Related Art 
     In a mobile communications system, a home zone service provides a different charging rate to a subscriber so that one of the charging rate is equivalent to an ordinary wired communication charge when the call is made within the home zone registered by the subscriber. For example, if the subscriber registers a specific area as his or her home zone with the mobile communications system, the air time charges can be charged at a significantly lower rate than normal. In order to establish the home zone specified by the subscriber, the mobile communication system collects location information (latitudes and longitudes) of the base stations, their respective communication coverage information, etc., based on the address specified by the subscriber. The present invention provides an improved apparatus and method for determining a charging rate for a call connection using a predetermined zone database. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide an apparatus for constructing a zone database to identify the home zone for a call connection requested by a subscriber in a mobile communication system, and a method for providing the home zone services using the zone database. 
     According to an aspect of the present invention, a method for constructing a zone database for providing home zone services to the subscribers of a mobile communication system, comprising the steps of: dividing a service area into a plurality of home service zones; simulating communication coverage area of the base stations for each of the home service zones; detecting the pilot signal strengths of the base stations; and, selecting a given number of the base stations in the order of pilot signal strength as the home zone. 
     According to another object of the invention, an apparatus for providing a home zone database used to determine a charging rate for a call connection with a mobile station within a mobile telecommunications network, comprising: a first storing means for storing data associated with a plurality of base stations, geographic data, system parameters, and antenna information of said mobile network; a simulating means for simulating a communication coverage for said base stations using the data stored in said first storing means; a detecting means for detecting the pilot signal strength of said base stations simulated by said simulating means; a second means for storing said detected pilot signal strength according to each of said base station; and, a sorting means for selecting a predetermined number of said base stations in the order of pilot signal strength, said selected predetermined base stations are stored in said home zone database. 
    
    
     The foregoing and other objects, features, and advantages of the invention will be apparent from the following, more detailed description of preferred embodiments as illustrated in the accompanying drawings in which reference characters refer to the same parts throughout the various views. The drawings are not necessarily to scale, the emphasis instead placed upon illustrating the principles of the invention. 
     BRIEF DESCRIPTION OF THE ATTACHED DRAWINGS 
     FIG. 1 is a block diagram for illustrating the structure of an apparatus for constructing a zone database for providing home zone services in a mobile communication system according to the present invention; 
     FIG. 2 is a diagram for illustrating the division of a service area into a plurality of home service zones, and the distribution of the base stations whose pilot signals are detected by a particular home zone; 
     FIG. 3 is a flow chart for illustrating the process of constructing a zone database for providing home zone services according to the present invention; 
     FIG. 4 is a flow chart for illustrating the process of determining the home zone database of a subscriber according to the present invention; and, 
     Fig. 5 is a flow chart for illustrating the process of providing home zone services based on a zone database according to the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     In the following description, for purposes of explanation rather than limitation, specific details are set forth such as the particular architecture, interfaces, techniques, etc., in order to provide a thorough understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention may be practiced in other embodiments that depart from these specific details. For the purpose of clarity, detailed descriptions of well-known devices, circuits, and methods are omitted so as not to obscure the description of the present invention with unnecessary detail. 
     With reference to FIG. 1, according to the embodiment of the present invention, a parameter database (DB)  100  is provided to store various information used for simulating coverage area, such as system parameters, base stations, geographic data, antennas, etc. A zone data generator  200  includes a coverage simulator  220 , a pilot signal detector  230 , a pilot signal related base station data storage  240 , a sorting/selection unit  260 , a base station DB  280 , and a PN offset related data base storage  290 . 
     The coverage simulator  220  makes a coverage simulation of each base station by using the information stored in the parameter DB  100 . In this case, the operational unit is bin. It is well known in the art that information contained in the parameter DB  100  can be represented in a bin. Through a binning process, bins of various data points are formed based on the information stored in the parameter DB  100 . Bin positions are determined from the bins. Bin positions define the order of bins along each discretized axis and can be determined from bin numbers associated with the bins. The pilot signal detector  230  detects the pilot signal of each base station in bin unit. The pilot signal related base station data storage  240  then stores the detected pilot signal level of the corresponding base station in a given bin position. Here, the PN offset of the base station is also included in the base station data  240 . The PN offset is utilized to discern between base stations associated with users. Thus, the generated data stored in the pilot signal related base station data storage  240  includes the pilot signal strength, PN offset, and base station data. The base station DB  280  stores the base station data to distinguish between base stations. The sorting/selection unit  260  in turn selects a predetermined number (e.g., 8) of pilot signals in the order of pilot signal strength. The PN offset related base station data storage  290  performs data arrangement according to the data format demanded by the zone DB  300 , which stores the zone data files received from the PN offset related base station data storage  290 . Accordingly, each bin position, defining a home zone, is represented by the data processed according to the above process to be stored in the zone DB  300 . 
     FIG. 2 illustrates how each bin position is processed using the above-described means. The coverage simulator (RSSI detection simulator)  220 , as shown in FIG. 1, determines the home zone  500  based on the pilot signal strength received from the surrounding base stations A to H. A predetermined number of the surrounding base stations in the order of pilot signal strength is selected according to the embodiment of the present invention. 
     FIG. 3 further illustrates the process of constructing a zone database  300  to tabularize home zone services according to the present invention. Referring to FIG. 3, the zone data generator  200  initially divides a service area into a plurality of home service zones in the unit of a bin, in step  3   a . By setting the home zone identification variable “n” to 1 in step  3   b , the coverage simulation is initially made for the first home zone to detect the pilot signal strengths of the surrounding base stations in step  3   c . Detected pilot signals from the respective base stations are sorted according to their strength in step  3   d  and a predetermined number of the base stations (i.e., 8) is selected in step  3   e  in the order of pilot signal strength. The selected base stations defines the home zone corresponding to the one of the divided plurality of home service zones in step  3   f . More specifically, the base station data with the PN offsets of the selected base stations are retrieved from the base station DB  280  during the process of preparing the zone database. If all home zones are not detected for all divided home service zones in step  3   g , the steps  3   c  to  3   f  are repeated until the home zone identification variable “n” becomes equal to the total number of divided home service zones through step  3   h.    
     The zone database constructed as describe above is kept in the base station or control center so that a comparison can be made to determine whether the mobile station is located within the home zone or not. Accordingly, different billing scheme can be applied to the mobile subscriber. 
     FIG. 4 describes the process of determining the home zone area of a mobile subscriber. As shown in FIG. 4, the control center enters the address information of the mobile subscriber who is seeking the home zone services in step  4   a . It also determines the site information of the subscriber corresponding to the address information using the GIS (Geographic Information System) tool in step  4   b . In step  4   c , the zone database  300  is searched to retrieve the base station information corresponding to the determined site information. Here, a given number base stations, as determined in FIG. 3, that is assigned to the corresponding site information is retrieved to construct the home zone database for the subscriber. Thus, the home zone database will include a given number, e.g., 8, of the base stations. It should be noted that the zone DB  300  can be used to define a home zone for a subscriber as dictated by the operator. 
     FIG. 5 illustrates the process of providing the home zone services using the zone database. The control center determines in step  5   a  whether there is a call setup request, a site registration demand, or the activation of a home zone confirmation key (e.g., *69) from a mobile station. If so, the control center detects, in step  5   b , the base station information to identify the base station serving the requesting mobile station. The base station information includes site ID, sector ID, etc. In step  5   c , the control center determines whether the detected base station information is included in the home zone DB that is created in FIG.  4 . The home zone database also includes site ID, sector ID, etc. If so, the control center determines in step  5   d  that the subscriber is located within the registered home zone and applies a first price rate, e.g., ordinary wired telephone price rate. Otherwise, the control center determines in step  5   e  that the subscriber is located outside the home zone and applies a second price rate, e.g., mobile telephone price rate. 
     As explain, the present invention provides the means for constructing a zone database for providing the home zone communication services. While the present invention has been described in connection with specific embodiments accompanied by the attached drawings, it will be readily apparent to those skilled in the art that various changes and modifications may be made thereto without departing the gist of the present invention.