Abstract:
An apparatus and a method for measuring reception power of a base station in a mobile communication terminal having at least two Subscriber Identity Module (SIM) cards is disclosed. The apparatus includes a first terminal unit associated with a first SIM card and a terminal unit associated with each of the remaining at least two SIM cards. The first terminal unit measures a reception power of at least one base station when the mobile communication terminal operates in an idle mode. The terminal units associated with the remaining at least two SIM cards shares the reception power of the at least one base station measured by the first terminal unit.

Description:
CLAIM OF PRIORITY 
     This application claims the benefit of the earlier filing date, under 35 U.S.C. §119(a), to that patent application filed in the Korean Intellectual Property Office on Jan. 5, 2009 and assigned Serial No. 10-2009-0000303, the entire disclosure of which is hereby incorporated by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to portable devices and more to an apparatus and a method for reducing current consumption occurring during an idle mode 
     2. Description of the Related Art 
     A mobile communication device having a dual operational mode includes at least one terminal unit associated with each Subscriber Identity Module (SIM) card. That is, a mobile communication terminal having a dual operational mode includes a first terminal unit for a first SIM card and a second terminal unit for a second SIM card that are integrated into one unit. The first terminal unit and the second terminal unit share only data related to a user interface, but operate independently. Here, the terminal unit includes at least one module for performing communication. 
     When operating in an idle mode, a mobile communication device measures reception power of a serving base station and at least one neighbor base station. The first terminal unit and the second terminal unit each measure the reception power of the serving base station and the at least one neighbor base station independently. Therefore, when the mobile communication device having a dual SIM card operates in an idle mode, current consumption increases compared to a mobile communication terminal having only one terminal unit, as each mode performs essentially the same operation. 
     SUMMARY OF THE INVENTION 
     An aspect of the present invention is to provide an apparatus and a method for reducing current consumption in a mobile communication terminal having a dual SIM card. 
     Another aspect of the present invention is to provide an apparatus and a method for reducing current consumption occurring while a mobile communication device having a dual SIM card operates in an idle mode. 
     Still another aspect of the present invention is to provide an apparatus and a method for operating only a terminal unit for one SIM card in the case where a mobile communication terminal having a dual SIM card operates in an idle mode. 
     Yet another aspect of the present invention is to provide an apparatus and a method for reducing current consumption by allowing at least two terminal units forming a mobile communication terminal having a dual SIM card to share reception power information of a serving base station and neighbor base stations. 
     In accordance with an aspect of the present invention, an apparatus for measuring reception power of a base station in a mobile communication terminal having at least two Subscriber Identity Module (SIM) cards is provided. The apparatus includes a first terminal unit containing a first SIM card, for measuring reception power of at least one base station when the mobile communication terminal operates in an idle mode, and at least one additional terminal unit containing a corresponding at least one SIM card, for sharing the reception power of the at least one base station measured by the first terminal unit. 
     In accordance with another aspect of the present invention, a method for measuring reception power of a base station in a mobile communication terminal having at least two Subscriber Identity Module (SIM) cards is provided. The method includes, when the mobile communication terminal operates in an idle mode, measuring reception power of at least one base station using a first terminal unit, and transmitting reception power of the at least one base station measured by the first terminal unit to at least one additional terminal unit. 
     Other aspects, advantages and salient features of the invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses exemplary embodiments of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other aspects, features and advantages of certain exemplary embodiments of the present invention will be more apparent from the following description taken in conjunction with the accompanying drawings in which: 
         FIG. 1  is a block diagram illustrating a mobile communication terminal supporting a dual SIM card according to an exemplary embodiment of the present invention; 
         FIG. 2  is a flowchart for measuring reception power at a terminal unit set as a master module of a mobile communication terminal according to an exemplary embodiment of the present invention; 
         FIG. 3  is a flowchart for receiving reception power information from a terminal unit set as a master module to a terminal unit set as a slave module of a mobile communication terminal according to an exemplary embodiment of the present invention; 
         FIG. 4  is a flowchart illustrating a procedure for measuring reception power in a terminal unit set as a master module of a mobile communication terminal according to an exemplary embodiment of the present invention; 
         FIG. 5  is a flowchart illustrating a procedure for receiving reception power information from a terminal unit set as a master module to a terminal unit set as a slave module of a mobile communication terminal according to an exemplary embodiment of the present invention; and 
         FIG. 6  is a flowchart for measuring reception power at a terminal unit set as a slave module of a mobile communication terminal according to an exemplary embodiment of the present invention. 
     
    
    
     Throughout the drawings, like reference numerals will be understood to refer to like parts, components and structures. 
     DETAILED DESCRIPTION OF THE INVENTION 
     The following description, with reference to the accompanying drawings, is provided to assist in a comprehensive understanding of exemplary embodiments of the invention as defined by the claims and their equivalents. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary. 
     Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope and spirit of the invention. Also, descriptions of well-known functions and constructions are omitted for clarity and conciseness. 
     The terms and words used in the following description and claims are not limited to the bibliographical meanings, but, are merely used by the inventor to enable a clear and consistent understanding of the invention. Accordingly, it should be apparent to those skilled in the art that the following description of exemplary embodiments of the present invention are provided for illustration purpose only and not for the purpose of limiting the invention as defined by the appended claims and their equivalents. 
     Exemplary embodiments of the present invention provide a technique for reducing current (power) consumption in a mobile communication terminal having a dual SIM card. 
     A typical mobile communication terminal having a dual SIM card has the construction illustrated in  FIG. 1 . 
       FIG. 1  is a block diagram illustrating a mobile communication terminal supporting a dual SIM card according to an exemplary embodiment of the present invention. 
     Referring to  FIG. 1 , the mobile communication terminal  100  includes a first terminal unit  110  supporting a first SIM card, a second terminal unit  120  supporting a second SIM card, and a power measurement controller  130 . Since the first terminal unit  110  and the second terminal unit  120  have the same construction, description of the construction of the second terminal unit  120  is omitted. 
     The first terminal unit  110  includes a receiver  111 , a power measuring unit  113 , and a controller  115 . Although not shown it would be recognized that the controller may include one or more processing units that may be in communication with one or more storage units. The storage units may be internal or external to the one or more processing units. 
     The receiver  111  converts a Radio Frequency (RF) signal received via an antenna (not labeled) into a baseband signal. At this point, when the mobile communication terminal  100  operates in an idle mode, the receiver  111  is driven under control of the controller  115 . 
     The power measuring unit  113  measures reception power of a serving base station using a signal received from the serving base station via the receiver  111 . In addition, the power measuring unit  113  measures reception power of each neighbor base station using a signal received from at least one neighbor base station via the receiver  111 . At this point, when the mobile communication terminal  100  operates in the idle mode, the power measuring unit  113  is driven under control of the controller  115 . 
     When the mobile communication terminal  100  operates in the idle mode, the controller  115  controls driving of the receiver  111  and the power measuring unit  113  under control of the power measurement controller  130 . For example, in the case where the power measurement controller  130  sets the first terminal unit  110  as a master module, the controller  115  activates the receiver  111  and the power measuring unit  113 . As another example, in the case where the power measurement controller  130  sets the first terminal unit  110  as a slave module, the controller  115  inactivates the receiver  111  and the power measuring unit  113 . At this point, the controller  115  may inactivate only the power measuring unit  113 . 
     When the receiver  111  and the power measuring unit  113  are activated, the controller  115  transmits reception power information of a serving base station and a neighbor base station provided from the power measuring unit  113  to the second terminal unit  120 . For example, the controller  115  periodically transmits the reception power information of the serving base station and the neighbor base station to a controller  125  of the second terminal unit  120 . As another example, when reception power of the serving base station and the neighbor base station changes, the controller  115  transmits the reception power of the serving base station and the neighbor base station to the controller  125  of the second terminal unit  120 . 
     When the receiver  111  and the power measuring unit  113  are inactivated, the controller  115  receives reception power information of the serving base station and the neighbor base station from the second terminal unit  120 . 
     When the power measurement controller  130  sets the first terminal unit  110  as a slave module but a disorder of the second terminal unit  120  is detected, the controller  115  activates the receiver  111  and the power measuring unit  113 . For example, when an error occurred signal is received from the second terminal unit  120 , (i.e., a disorder) the controller  115  recognizes that a disorder has occurred at the second terminal unit  120 . For another example, when reception power information of a base station is not received for a reception power transmission period from the second terminal unit  120 , the controller  115  may recognize a disorder has occurred to the second terminal unit  120 . 
     When the mobile communication terminal  100  switches to the idle mode, the power measurement controller  130  determines a master module for measuring reception power of a serving base station and a neighbor base station among the first terminal unit  110  and the second terminal unit  120 . For example, the power measurement controller  130  compares electric field strengths of the first terminal unit  110  and the second terminal unit  120  to determine a master module. Although not shown it would be recognized that the controller  130  may include one or more processing units that may be in communication with one or more storage units. The storage units may be internal or external to the one or more processing units. In addition, the storage units of processor  130  may be shared with the processors of controllers  115  and  125 . That is, the storage units may be dual-port memories that may be accessed by the processors of controllers  115  and  125 . 
     In the above-described exemplary embodiment of the present invention, when switching to the idle mode, the mobile communication terminal determines a master module for measuring reception power of a serving base station and neighbor base stations. 
     In an exemplary embodiment of the present invention, the mobile communication terminal may fix one of the first terminal unit  110  and the second terminal unit  120  as a master module. In this case, the mobile communication terminal does not include the power measurement controller  130 . 
     As described above, when a mobile communication terminal having a dual SIM card operates in the idle mode, the mobile communication terminal activates only a terminal unit set as a master module. Accordingly, the terminal unit set to the master module measures reception power of a serving base station and a neighbor base station as illustrated in  FIG. 2 . 
       FIG. 2  is a flowchart for measuring reception power at a terminal unit set as a master module of a mobile communication terminal according to an exemplary embodiment of the present invention. 
     Referring to  FIG. 2 , the terminal unit determines whether the terminal unit is set as the master module in step  201 . 
     When set as the master module, the terminal unit measures reception power of a serving base station and at least one neighbor base station using signals received from the serving base station and the at least one neighbor base station in step  203 . For example, the terminal unit periodically measures reception power of the serving base station and the neighbor base station. At this point, the terminal unit stores the measured reception power of the serving base station and the neighbor base station in a storing unit. 
     After measuring the reception power of the serving base station and the neighbor base station, the terminal unit determines a transmission period of reception power information in step  205 . Here, the transmission period of the reception power information may be or may not be the same as a period at which the terminal unit determines reception power. 
     The terminal unit determines whether the transmission period of the reception power information (determined in step  205 ) arrives in step  207  which means that a time of transmission has arrived. 
     When the transmission period of the reception power information arrives the terminal unit transmits the reception power of the serving base station and the neighbor base station (measured in step  203 ) to a terminal unit set to a slave module in step  209 . 
     After that, the terminal unit ends the present algorithm. 
     As described above, in the case where a terminal unit set as a master module transmits reception power of a serving base station and a neighbor base station, a terminal unit set to a slave module determines reception power of the serving base station and the neighbor base station as illustrated in  FIG. 3 . In the following description, it is assumed that the terminal unit set as the slave module recognizes a disorder of the terminal unit set as the master module depending on whether reception power information of a base station is received from the terminal unit set as the master module at a reception power transmission period. 
       FIG. 3  is a flowchart for receiving reception power information from a terminal unit set as a master module at a terminal unit set as a slave module of a mobile communication terminal according to an exemplary embodiment of the present invention. Referring to  FIG. 3 , the terminal unit determines whether the terminal unit has been set as the slave module in step  301 . 
     When the terminal has been set as the slave module, the terminal unit inactivates at least one of a receiver and a power measuring unit in step  303 . For example, the terminal unit may inactivate only the power measuring unit. For another example, the terminal unit may inactivate both the receiver and the power measuring unit. 
     After switching to an inactive mode, the terminal unit determines a transmission period of reception power information in step  305 . 
     The terminal unit determines whether reception power information of a base station is received from the terminal unit set as the master module at the transmission period (determined in step  305 ) in step  307 . Here, the reception power information of the base station includes reception power information of a serving base station and at least one neighbor base station. 
     When the reception power information of the base station is received at the transmission period of the reception power information, the terminal unit determines reception power of the serving base station and the at least one neighbor base station measured by the terminal unit set as the master module in step  309 . At this point, the terminal unit stores the reception power of the serving base station and the at least one neighbor base station provided by the terminal unit set as the master module in a storing unit as if the terminal unit set as the slave module measured the reception power. 
     When the transmission period of the reception power information arrives but the reception power information of the base station is not received, the terminal unit recognizes a disorder has occurred to the terminal unit set as the master module in step  311 . In one aspect of the invention, a disorder may be determined based on no power being received. In another aspect of the invention, a disorder may be determined based on the received power being less than a known threshold value. 
     The terminal unit activates the inactivated module (in step  303 ) in step  313 . For example, the terminal unit activates the power measuring unit inactivated (in step  303 ). For another example, the terminal unit may activate both the receiver and the power measuring unit inactivated (in step  303 ). 
     After switching the inactivated module to an active mode, the terminal unit measures reception power of a serving base station and at least one neighbor base station using signals provided from the serving base station and the at least one neighbor base station in step  315 . For example, the terminal unit periodically measures the reception power of the serving base station and the neighbor base station. At this point, the terminal unit stores the measured reception power of the serving base station and the neighbor base station in a storing unit. 
     After that, the terminal unit ends the present algorithm. 
     The terminal unit set as the master module may measure reception power as illustrated in  FIG. 4 . 
       FIG. 4  is a flowchart illustrating a procedure for measuring reception power in a terminal unit set to a master module of a mobile communication terminal according to an exemplary embodiment of the present invention. 
     Referring to  FIG. 4 , the terminal unit determines whether the terminal unit has been set as the master module in step  401 . 
     When set as the master module, the terminal unit measures reception power of a serving base station and at least one neighbor base station using signals received from the serving base station and the at least one neighbor base station in step  403 . In one aspect of the invention, the terminal unit periodically measures reception power of the serving base station and the neighbor base station. The terminal unit may store the measured reception power of the serving base station and the neighbor base station in a storing unit after each measurement (not shown). 
     After measuring the reception power of the serving base station and the neighbor base station, the terminal unit compares the reception power of the base stations determined in step  403  with previously determined reception power of the base stations to determine whether the reception power of the base stations has changed in step  405 . 
     When the reception power of the base stations has changed, the terminal unit transmits the reception power of the serving base station and the at least one neighbor base station determined in step  403  to a slave module in step  407 . 
     However, when the reception power of the base stations has not changed, the terminal unit determines whether a transmission period of reception power information arrives in step  409 . Here, the transmission period of the reception power information may be or may not be the same as a period at which the terminal unit determines reception power. 
     When the transmission period of the reception power information does not arrive, the terminal unit again determines the reception power of the signals transmitted by each of the serving base station and the neighbor base station in step  403 . 
     In contrast, when the transmission period of the reception power information arrives, the terminal unit transmits reception power of the serving base station and the at least one neighbor base station determined in step  403  to the slave module in step  407 . That is, even when the reception power of the base stations does not change, the terminal unit transmits the reception power information of the base stations to a terminal unit set to the slave module each time a measurement is attempted. Thus, when the measurement of received power is performed periodically, a measurement is provided to slave station whether a measurement has been performed within the time period (window) of measurement or not. 
     After that, the terminal unit ends the present algorithm. 
     As described above, when a terminal unit set as a master module transmits reception power of a serving base station and at least one neighbor base station to the slave module, the terminal unit set as the slave module determines the reception power of the serving base station and the neighbor base station as illustrated in  FIG. 5 . 
     In the following description, it is assumed that the terminal unit set as the slave module recognizes a disorder of the terminal unit set as the master module depending on whether reception power information of a base station is received from the terminal unit set as the master module at a reception power transmission period. 
       FIG. 5  is a flowchart illustrating a procedure for receiving reception power information from a terminal unit set as a master module at a terminal unit set as a slave module of a mobile communication terminal according to an exemplary embodiment of the present invention. 
     Referring to  FIG. 5 , the terminal unit determines whether the terminal unit has been set as a slave module in step  501 . 
     When set as the slave module, the terminal unit inactivates at least one of a receiver and a power measuring unit in step  503 . For example, the terminal unit may only inactivate the power measuring unit. In another aspect of the invention, the terminal unit may inactivate both the receiver and the power measuring unit. 
     The slave terminal unit determines whether reception power information of a base station is received from a terminal unit set as a master module in step  505 . Here, the reception power information of the base station includes reception power information of a serving base station and at least one neighbor base station. 
     When the reception power information of the base station is received, the slave terminal unit determines the reception power of the serving base station and the at least one neighbor base station measured by the terminal unit set as the master module in step  507 . if the answer is in the affirmative, the slave terminal unit stores the reception power of the serving base station and the at least one neighbor base station provided by the terminal unit set as the master module in a storing unit as if the terminal set as the slave module measured the reception power itself. 
     However, when the reception power information of the base station is not received, the terminal unit determines whether a period of reception power information arrives in step  509 . 
     When the period of reception power information does not arrive, the slave terminal unit returns to step  505  to determine whether reception power information of the base stations has been received from the terminal unit set as the master module. 
     However, when the period of reception power information arrives the terminal unit recognizes that a disorder has occurred to the master module in step  511 . In one aspect of the invention, a disorder may be determined based on no power being received. In another aspect of the invention, a disorder may be determined based on the received power being less than a known threshold value. 
     In this case, the slave terminal unit activates the module(s) inactivated in step  503  in step  513 . For example, the terminal unit activates the inactivated power measuring unit (in step  503 ). For another example, the terminal unit activates both the receiver and the power measuring unit if both units have been inactivated. 
     After activating the inactivated module(s), the terminal unit measures reception power of the serving base station and the neighbor base station using signals transmitted from the serving base station and the neighbor base station in step  515 . In one aspect, the terminal unit periodically measures the reception power of the serving base station and the neighbor base station. At this point, the terminal unit stores the measured reception power in a storing unit (not shown). 
     After that, the terminal unit ends the present algorithm. 
     In the above-described exemplary embodiment of the present invention, the terminal unit set as the slave module recognizes a disorder of the terminal unit set as the master module depending on whether reception power information of the base station is received from the terminal unit set to the master module. 
     In another aspect of the present invention, a terminal unit set as a master module may transmit an “error occurred” information to a terminal unit set as a slave module when a disorder of the terminal set to the master module is recognized. In this case, the terminal unit set to the slave module may operate as illustrated in  FIG. 6 . 
       FIG. 6  is a flowchart for measuring reception power at a terminal unit set as a slave module of a mobile communication terminal according to an exemplary embodiment of the present invention. 
     Referring to  FIG. 6 , the terminal unit determines whether the terminal unit has been set as a slave module in step  601 . 
     When set as the slave module, the terminal unit inactivates at least one of a receiver and a power measuring unit in step  603 , as previously describe. 
     The terminal unit determines whether “error occurred” information has been received from a terminal unit set as a master module in step  605 . 
     When the “error occurred” information is not received, the terminal unit stands by in order to receive reception power information of a base station transmitted by the terminal unit set as the master module. 
     However, when the “error occurred” information is received, the terminal unit recognizes a disorder has occurred to the terminal unit set as the master module in step  607 . 
     The terminal unit activates the inactivated module(s) in step  609 , as previously described. Although not shown, it would be recognized that when the inactivated module is activated, the active module is inactivated. 
     After activating the inactivated module(s) the terminal unit measures reception power of the serving base station and the neighbor base station using signals transmitted from the serving base station and the neighbor base station in step  611 . For example, the terminal unit periodically measures the reception power of the serving base station and the neighbor base station. At this point, the terminal unit stores the measured reception power in a storing unit. 
     After that, the terminal unit ends the present algorithm. 
     In the above-described exemplary embodiment of the present invention, a mobile communication terminal has two SIM cards. However, exemplary embodiments of the present invention are applicable to a mobile communication terminal having two or more SIM cards. For example, in the case where a mobile communication terminal has three SIM cards, the mobile communication terminal sets a terminal unit for one SIM card as a master module and sets terminal units for the other two SIM cards as slave modules. When an error occurs in the terminal unit set as the master module, the mobile communication terminal may measure reception power of base stations using one or both of the two terminal units set as the slave modules. At this point, the mobile communication terminal may set one of the two terminal units set as the slave modules, to the master module. 
     As described above, in the case where a mobile communication terminal having a dual SIM card operates in an idle mode, terminal units for respective SIM cards share reception power information of a serving base station and neighbor base stations, so that current consumption can be reduced. 
     Although the invention has been shown and described with reference to certain exemplary embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims and their equivalents. Therefore, the scope of the present invention should not be limited to the above-described embodiments but should be determined by not only the appended claims but also the equivalents thereof.