Abstract:
A wireless communication device includes a memory, and a processor coupled to the memory and configured to extract a control code from a signal received through a first communication system that has lower priority than a second communication system prior to carrying out communication through the second communication system, compare the extracted control code with a given control code stored in the memory, determine whether the extracted control code matches the given control code, and cause a communication device that is configured to carry out communication through the second communication system to stop processing for establishing a wireless communication when the processor determines that the extracted control code does not match the given control code.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2013-012702, filed on Jan. 25, 2013, the entire contents of which are incorporated herein by reference. 
       FIELD 
       [0002]    The embodiments discussed herein are related to wireless communication devices and so forth. 
       BACKGROUND 
       [0003]    There exists a multi-wireless terminal that is capable of wireless communication through the universal mobile telecommunications system (UMTS) and the time division long term evolution (TD-LTE) system. 
         [0004]    Japanese National Publication of International Patent Application No. 2008-543136, Japanese Laid-open Patent Publication No. 2007-235593, and Japanese Laid-open Patent Publication No. 2008-271251 are examples of related art. 
       SUMMARY 
       [0005]    According to an aspect of the invention, a wireless communication device includes a memory, and a processor coupled to the memory and configured to extract a control code from a signal received through a first communication system that has lower priority than a second communication system prior to carrying out communication through the second communication system, compare the extracted control code with a given control code stored in the memory, determine whether the extracted control code matches the given control code, and cause a communication device that is configured to carry out communication through the second communication system to stop processing for establishing a wireless communication when the processor determines that the extracted control code does not match the given control code. 
         [0006]    The object and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the claims. 
         [0007]    It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention, as claimed. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0008]      FIG. 1  illustrates an example of multi-wireless system of an embodiment; 
           [0009]      FIG. 2  is a functional block diagram illustrating a configuration of a multi-wireless terminal according to the embodiment; 
           [0010]      FIG. 3  is a functional block diagram illustrating a configuration of a control unit; 
           [0011]      FIG. 4  illustrates an exemplary data structure of a UMTS downlink physical channel; 
           [0012]      FIG. 5  illustrates an exemplary data structure of a PLMN code; 
           [0013]      FIG. 6  is a flowchart illustrating a processing procedure for obtaining a PLMN code through a UMTS wireless communication; 
           [0014]      FIG. 7  illustrates an exemplary data structure of an LTE downlink physical channel; 
           [0015]      FIG. 8  is a flowchart illustrating a processing procedure for obtaining a PLMN code through a TD-LTE wireless communication; 
           [0016]      FIG. 9  illustrates an exemplary data structure of PLMN code information; 
           [0017]      FIG. 10  is a flowchart ( 1 ) illustrating a processing procedure of the multi-wireless terminal of the embodiment; 
           [0018]      FIG. 11  is a flowchart ( 2 ) illustrating the processing procedure of the multi-wireless terminal of the embodiment; 
           [0019]      FIG. 12  is a diagram for describing a wireless terminal device that executes a control program; 
           [0020]      FIG. 13  illustrates examples of a communication area in which communication is available through the UMTS system and of communication areas in which communication is available through the TD-LTE system; and 
           [0021]      FIG. 14  is a flowchart illustrating a processing procedure of a multi-wireless terminal. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0022]    Hereinafter, an embodiment of a wireless communication device, a control program, and a control method disclosed herein will be described in detail with reference to the drawings. Embodiments, however, are not limited to the embodiments discussed herein. 
         [0023]    While inventing the present embodiments, observations were made regarding a related art. Such observations include the following, for example. 
         [0024]      FIG. 13  illustrates examples of a communication area in which communication is available through the UMTS system and of communication areas in which communication is available through the TD-LTE system. Here, a communication area in which communication is available through the UMTS system is referred to as a UMTS communication area  1   a , and a communication area in which communication is available through the TD-LTE system is referred to as a TD-LTE communication area  1   b . The population coverage rate in the UMTS communication area  1   a  is 98% or higher. Meanwhile, the population coverage rate in the TD-LTE communication area  1   b  is approximately 60%. 
         [0025]    In general, the communication speed is higher in the TD-LTE system than in the UMTS system. Thus, if a multi-wireless terminal is located at a location within both the UMTS communication area  1   a  and the TD-LTE communication area  1   b , wireless communication through the TD-LTE system takes priority. If the multi-wireless terminal then goes outside the TD-LTE communication area  1   b , the multi-wireless terminal switches to the UMTS system to carry out wireless communication. A multi-wireless terminal carries out processing for detecting a TD-LTE base station repeatedly even after the multi-wireless terminal goes outside the TD-LTE communication area  1   b  in order to determine whether the multi-wireless terminal has entered the TD-LTE communication area  1   b  again. If the multi-wireless terminal detects a TD-LTE base station, the multi-wireless terminal switches to the TD-LTE system from the UMTS system to carry out wireless communication. 
         [0026]    The TD-LTE is the latest wireless service, and thus, for the time being, it is not possible to connect to an overseas service provider by wireless communication through TD-LTE system due to the differences in specifications and so on. In China, for example, although a multi-wireless terminal can receive data through the TD-LTE system, the multi-wireless terminal is unable to transmit data through the TD-LTE system. Thus, even if a user takes a multi-wireless terminal to China, the user is unable to carry out wireless communication through the TD-LTE system. However, if the user carries out wireless communication through the UMTS system, the user can connect to an overseas service provider, which enables overseas roaming. 
         [0027]    In order to handle such differences in the specifications, the multi-wireless terminal stops transmitting data through the TD-LTE system once and then receives a public land mobile network (PLMN) code from a broadcast control channel (BCCH) in TD-LTE to determine whether the multi-wireless terminal is located domestically or overseas. If the received PLMN code is not a PLMN code of a domestic service provider, the multi-wireless terminal determines that the multi-wireless terminal is located overseas and thus carries out control for not establishing a wireless communication through the TD-LTE system. Meanwhile, if the PLMN code is a PLMN code of a domestic service provider, the multi-wireless terminal determines that the multi-wireless terminal is not located overseas and thus establishes a wireless communication through the TD-LTE system. 
         [0028]    An exemplary processing procedure of the multi-wireless terminal will be described.  FIG. 14  is a flowchart illustrating a processing procedure of the multi-wireless terminal. As illustrated in  FIG. 14 , when the power supply of the multi-wireless terminal is turned on (step S 10 ), the multi-wireless terminal carries out synchronization for UMTS wireless reception (step S 11 ) and obtains a PLMN code (step S 12 ). 
         [0029]    The multi-wireless terminal then establishes a UMTS wireless communication (step S 13 ) and attempts to detect a TD-LTE wireless signal (step S 14 ). The multi-wireless terminal determines whether the multi-wireless terminal has detected a TD-LTE wireless signal (step S 15 ). If the multi-wireless terminal has detected a TD-LTE wireless signal (step S 15 , Yes), the multi-wireless terminal receives a TD-LTE BCCH and obtains a PLMN code (step S 16 ). Thereafter, the multi-wireless terminal determines whether the obtained PLMN code is a PLMN code of a specified service provider (step S 17 ). If the obtained PLMN code is the PLMN code of the specified service provider (step S 17 , Yes), the multi-wireless terminal establishes a TD-LTE wireless communication (step S 18 ). Meanwhile, if the obtained PLMN code is not the PLMN code of the specified service provider (step S 17 , No), the multi-wireless terminal proceeds to step S 19 . 
         [0030]    In step S 15 , if the multi-wireless terminal does not detect a TD-LTE wireless signal (step S 15 , No), the multi-wireless terminal resets a search timer (step S 19 ). Upon the counter of the search timer reaching 0, the multi-wireless terminal attempts to detect a TD-LTE wireless signal (step S 20 ) and returns to step S 15 . 
         [0031]    As illustrated in  FIG. 14 , the multi-wireless terminal carries out, at regular intervals, processing in which the multi-wireless terminal receives a PLMN code from a TD-LTE BCCH to determine whether the multi-wireless terminal is located domestically or overseas. For example, in step S 17  of  FIG. 14 , if the PLMN code is not the PLMN code of the specified service provider, the multi-wireless terminal is determined to be located overseas. In this case, the multi-wireless terminal again detects a TD-LTE wireless signal after a given amount of time elapses to determine whether the multi-wireless terminal is located domestically or overseas. 
         [0032]    Thus, the technique described above has an issue that power is unnecessarily consumed in the multi-wireless terminal. 
         [0033]    The multi-wireless terminal carries out, at regular intervals, processing in which the multi-wireless terminal receives a PLMN code from a TD-LTE BCCH to determine whether the multi-wireless terminal is located domestically or overseas even after the multi-wireless terminal has once determined that the multi-wireless terminal is located overseas, which leads to wasteful power consumption. 
         [0034]    In one aspect, a wireless communication device, a control program, and a control method that are capable of reducing power consumption in a multi-wireless terminal is provided. 
         [0035]      FIG. 1  illustrates an example of a multi-wireless system of an embodiment. As illustrated in  FIG. 1 , this multi-wireless system includes a UMTS circuit switched network  2 , a UMTS packet network  3 , an LTE network  4 , and a home subscriber server (HSS)  5 . 
         [0036]    The UMTS circuit switched network  2  is connected to a UMTS base station  7 A. The UMTS packet network  3  is connected to the HSS  5 , a public data network (PDN)  6 , and the UMTS base station  7 A. The LTE network  4  is connected to the HSS  5 , the PDN  6 , and an LTE base station  7 B. 
         [0037]    The UMTS circuit switched network  2  includes a home location register (HLR)  21 , a mobile switching center (MSC)  22 , a gateway mobile switching center (GMSC)  23 , and a switchboard  24 . The HLR  21  registers and manages subscriber information, location information, and authentication information, which are associated with one another, of service subscribers in the UMTS circuit switched network  2 . The MSC  22  makes a switched communication with the UMTS base station  7 A. The GMSC  23  interconnects the MSC  22  and the switchboard  24 . 
         [0038]    The UMTS packet network  3  includes a serving GPRS support node (SGSN)  31  and a gateway GPRS support node (GGSN)  32 . The SGSN  31  is connected to the HSS  5 , the UMTS base station  7 A, and the GGSN  32  and relays a packet and so on. The GGSN  32  interconnects the SGSN  31  and the PDN  6 . 
         [0039]    The LTE network  4  includes a mobility management entity (MME)  41 , a serving-gateway (S-GW)  42 , and a packet data network gateway (P-GW)  43 . The MME  41  is connected to the HSS  5 , the LTE base station  7 B, and the S-GW  42  and manages network control such as sequence control within the LTE network  4 , a handover function, management of locations of service subscribers, and a paging function for an incoming call to the LTE base station  7 B. The S-GW  42  is connected to the LTE base station  7 B to manage a function of routing a packet. The P-GW  43  is a gateway for connecting to the PDN  6  wirelessly. 
         [0040]    The HSS  5  interconnects the SGSN  31  of the UMTS packet network  3  and the MME  41  of the LTE network  4 . In addition, the HSS  5  manages subscriber information and so on in the UMTS packet network  3  and the LTE network  4 . 
         [0041]    A multi-wireless terminal  100  is a terminal of a service subscriber, which is compatible with each wireless communication system within the multi-wireless system illustrated in  FIG. 1 . The multi-wireless terminal  100  first synchronizes wireless reception with the UMTS base station  7 A and receives a UMTS BCCH to obtain a PLMN code. If the obtained PLMN code matches a PLMN code of a specified domestic service provider, the multi-wireless terminal  100  attempts to carry out wireless communication through the TD-LTE system. Meanwhile, if the PLMN code that has been obtained through the UMTS BCCH reception differs from the PLMN code of the specified domestic service provider, the multi-wireless terminal  100  turns off the power supply of a device for establishing a wireless communication through the TD-LTE system. In this way, the multi-wireless terminal  100  turns off the power supply of the device for establishing a wireless communication through the TD-LTE system, and thus the multi-wireless terminal  100  does not attempt wireless communication through the TD-LTE system repeatedly, which makes it possible to reduce power consumption. 
         [0042]    Subsequently, the configuration of the multi-wireless terminal  100  illustrated in  FIG. 1  will be described.  FIG. 2  is a functional block diagram illustrating the configuration of the multi-wireless terminal according to the embodiment. As illustrated in  FIG. 2 , the multi-wireless terminal  100  includes a UMTS device  110 A and a TD-LTE device  110 B. The multi-wireless terminal  100  further includes a display unit  121 , an operation unit  122 , a microphone  123 , a speaker  124 , a memory  125 , and a central processing unit (CPU)  126 . Although not illustrated in  FIG. 2 , the multi-wireless terminal  100  may further include a Wireless Fidelity (Wi-Fi) device. 
         [0043]    The UMTS device  110 A is an interface for managing wireless communication with the UMTS circuit switched network  2  and the UMTS packet network  3 . The UMTS device  110 A includes an antenna  111 A, a UMTS wireless unit  112 A, and a UMTS baseband processing unit  113 A. The UMTS wireless unit  112 A receives a wireless signal including various pieces of data such as sound and characters that are compliant with the UMTS system through the antenna  111 A and carries out frequency conversion of the received wireless signal. The UMTS baseband processing unit  113 A converts the wireless signal that has been subjected to frequency conversion in the UMTS wireless unit  112 A to a baseband signal and demodulates the converted baseband signal. In addition, the UMTS baseband processing unit  113 A modulates transmission data into a baseband signal. The UMTS wireless unit  112 A carries out frequency conversion of the baseband signal that has been modulated in the UMTS baseband processing unit  113 A and outputs, through the antenna  111 A, a transmission signal obtained by carrying out frequency conversion of the baseband signal. 
         [0044]    The TD-LTE device  110 B is an interface for managing wireless communication with the LTE network  4 . The TD-LTE device  110 B includes an antenna  111 B, a TD-LTE wireless unit  112 B, and a TD-LTE baseband processing unit  113 B. The TD-LTE wireless unit  112 B receives a wireless signal of various pieces of data such as sound and characters that are compliant with the LTE system through the antenna  111 B and carries out frequency conversion of the received wireless signal. The TD-LTE baseband processing unit  113 B converts the wireless signal that has been subjected to frequency conversion in the TD-LTE wireless unit  112 B to a baseband signal and demodulates the converted baseband signal. In addition, the TD-LTE baseband processing unit  113 B modulates transmission data into a baseband signal. The TD-LTE wireless unit  1126  carries out frequency conversion of the baseband signal that has been modulated in the TD-LTE baseband processing unit  113 B and outputs, through the antenna  111 B, a transmission signal obtained by carrying out frequency conversion of the baseband signal. 
         [0045]    The display unit  121  is an output interface for displaying various pieces of information on a screen. The operation unit  122  is an input interface through which various pieces of information are inputted. The microphone  123  is an input interface for collecting various sounds. The speaker  124  is an output interface for outputting various sounds. The memory  125  is an area for storing various pieces of information. The CPU  126  is a device for controlling the multi-wireless terminal  100  as a whole. 
         [0046]    An exemplary configuration of a control unit that is included in the CPU  126  illustrated in  FIG. 2  will now be described.  FIG. 3  is a functional block diagram illustrating the configuration of the control unit. As illustrated in  FIG. 3 , a control unit  127  includes a UMTS communication processing unit  127   a,  a TD-LTE communication processing unit  127   b,  a determination unit  127   c,  and a communication control unit  127   d.    
         [0047]    The UMTS communication processing unit  127   a  cooperates with the UMTS device  110 A to establish a UMTS wireless communication. The UMTS communication processing unit  127   a  carries out synchronization for UMTS wireless reception to thus obtain a PLMN code. The UMTS communication processing unit  127   a  outputs information on the PLMN code to the determination unit  127   c.    
         [0048]    Processing through which the UMTS communication processing unit  127   a  obtains a PLMN code through a UMTS wireless communication will be described in detail.  FIG. 4  illustrates an exemplary data structure of a UMTS downlink physical channel. As illustrated in  FIG. 4 , UMTS includes frames that are each 10 ms in length and that each consist of 15 slots. Each of the slots includes a primary SCH (PSC), a secondary SCH (SSC), and a P-CCPCH. 
         [0049]    The UMTS communication processing unit  127   a  carries out synchronization processing on the PSC and the SSC to thus demodulate the P-CCPCH and obtains a PLMN code from a master information block (MIB) of a BCCH signal that has been obtained by demodulating the P-CCPCH. 
         [0050]      FIG. 5  illustrates an exemplary data structure of the PLMN code. As illustrated in  FIG. 5 , the PLMN code includes a mobile country code (MCC) and a mobile network code (MNC). For example, a domestic service provider A has a PLMN code where “MCC=440, MNC=20”, and an overseas service provider B has a PLMN code where “MCC=460, MNC=00”. A combination of an MNC and an MCC gives a code that is unique to each company, and thus the determination as to whether the multi-wireless terminal  100  is located domestically or overseas can be made on the basis of a PLMN code. 
         [0051]    A processing procedure through which the UMTS communication processing unit  127   a  obtains a PLMN code through a UMTS wireless communication will now be described.  FIG. 6  is a flowchart illustrating the processing procedure for obtaining a PLMN code through a UMTS wireless communication. As illustrated in  FIG. 6 , the UMTS communication processing unit  127   a  carries out synchronization processing on the primary SCH and on the secondary SCH to thus extract a scrambling group (step S 51 ). The UMTS communication processing unit  127   a  then demodulates the P-CCPCH to obtain a BCCH signal (step S 52 ) and obtains a PLMN code from the MIB of the BCCH signal (step S 53 ). 
         [0052]    The TD-LTE communication processing unit  127   b  cooperates with the TD-LTE device  110 B to establish a wireless communication through the TD-LTE system. The TD-LTE communication processing unit  127   b  synchronizes TD-LTE wireless reception to obtain a PLMN code. The TD-LTE communication processing unit  127   b  outputs information on the PLMN code to the determination unit  127   c.    
         [0053]    Processing through which the TD-LTE communication processing unit  127   b  obtains a PLMN code through a TD-LTE wireless communication will now be described in detail.  FIG. 7  illustrates an exemplary data structure of an LTE downlink physical channel. As illustrated in  FIG. 7 , a frame  50  of the LTE downlink physical channel includes a plurality of sub-frames  51 , and each of the sub-frames  51  includes a plurality of slots  52 . 
         [0054]    For example, a single frame is 10 ms in length and includes 10 sub-frames. A single sub-frame is 1 ms in length and includes two slots. A single slot is 0.5 ms in length. Here, each of the sub-frames  51  includes a primary synchronization signal  51 A and a secondary synchronization signal  51 B for synchronization and a PBCH signal  51 C for transporting the BCCH. 
         [0055]    The TD-LTE communication processing unit  127   b  achieves frame synchronization on the basis of the primary synchronization signal  51 A and the secondary synchronization signal  51 B and extracts a scrambling group for demodulating the PBCH. This scrambling group corresponds to a cell ID. The TD-LTE communication processing unit  127   b  demodulates the PBCH using the scrambling in order to obtain the BCCH. The TD-LTE communication processing unit  127   b  obtains a PLMN code that is contained in a system information block  1  (SIB 1 ) of the BCCH. The data structure of the PLMN code is similar to the one illustrated in  FIG. 5 , and thus description thereof will be omitted here. 
         [0056]    A processing procedure through which the TD-LTE communication processing unit  127   b  obtains a PLMN code through a TD-LTE wireless communication will now be described.  FIG. 8  is a flowchart illustrating the processing procedure for obtaining a PLMN code through a TD-LTE wireless communication. As illustrated in  FIG. 8 , the TD-LTE communication processing unit  127   b  carries out synchronization processing on a primary signal and on a secondary signal to thus extract a cell ID (step S 61 ). The TD-LTE communication processing unit  127   b  then demodulates the P-CCPCH to obtain a BCCH signal (step S 62 ) and obtains a PLMN code from the MIB of the BCCH signal (step S 63 ). 
         [0057]    If the power supply of the TD-LTE device  110 B is turned off, the TD-LTE communication processing unit  127   b  stops the processing for obtaining a PLMN code through the TD-LTE wireless communication. 
         [0058]    If the TD-LTE communication processing unit  127   b  obtains information, from the determination unit  127   c  (described later), indicating that the PLMN code is a PLMN code of a specified service provider in a state where the power supply of the TD-LTE device  110 B is turned off, the TD-LTE communication processing unit  127   b  establishes a TD-LTE wireless communication. 
         [0059]    On the other hand, if the TD-LTE communication processing unit  127   b  obtains information, from the determination unit  127   c  (described later), indicating that the PLMN code is not the PLMN code of the specified service provider in a state where the power supply of the TD-LTE device  110 B is turned off, the TD-LTE communication processing unit  127   b,  after a given time elapses, obtains a PLMN code again through the TD-LTE wireless communication and outputs the PLMN code to the determination unit  127   c.    
         [0060]    As described thus far, the UMTS communication processing unit  127   a  obtains a PLMN code through a UMTS wireless communication. The TD-LTE communication processing unit  127   b  obtains a PLMN code through a TD-LTE wireless communication. The UMTS communication processing unit  127   a  carries out the processing for obtaining a PLMN code before the TD-LTE communication processing unit  127   b  carries out such processing. 
         [0061]    In the description hereinafter, a PLMN code that has been obtained through a UMTS wireless communication is referred to as a first PLMN code, and a PLMN code that has been obtained through a TD-LTE wireless communication is referred to as a second PLMN code. 
         [0062]    The determination unit  127   c  is a processing unit for determining whether the first PLMN code received from the UMTS communication processing unit  127   a  matches a PLMN code of a specified domestic service provider included in PLMN code information  125   a.  The determination unit  127   c  outputs a determination result to the communication control unit  127   d.    
         [0063]    Here, the PLMN code information  125   a  contains combinations of an MCC and an MNC for respective companies located domestically and combinations of an MCC and an MNC for respective companies located overseas.  FIG. 9  illustrates an exemplary data structure of the PLMN code information. For example, the PLMN code information  125   a  contains MCCs, MNCs, countries, and service providers, which are associated with one another. In the embodiment, a specified domestic service provider having such attributes as the country being “Japan” and the service provider being “provider A” is used as an example. 
         [0064]    The determination unit  127   c  compares the MCC and the MNC in the first PLMN code with the MCCs and the MNCs in the PLMN code information  125   a  to thus determine whether the first PLMN code matches the PLMN code of the specified Japanese service provider. The determination unit  127   c  outputs, to the communication control unit  127   d,  a determination result indicating whether the first PLMN code matches the PLMN code of the specified Japanese service provider. 
         [0065]    In addition, the determination unit  127   c  determines whether the second PLMN code received from the TD-LTE communication processing unit  127   b  matches the PLMN code of the specified Japanese service provider included in the PLMN code information  125   a.  The processing for determining whether the second PLMN code matches the PLMN code of the specified Japanese service provider is similar to the above-described processing of the first PLMN code. The determination unit  127   c  outputs, to the TD-LTE communication processing unit  127   b,  a determination result indicating whether the second PLMN code matches the PLMN code of the specified Japanese service provider. 
         [0066]    The communication control unit  127   d  is a processing unit for controlling the power supply in TD-LTE on the basis of the determination result of the determination unit  127   c.  If the communication control unit  127   d  receives a determination result indicating that the first PLMN code matches the PLMN code of the specified Japanese service provider, the communication control unit  127   d  turns on the power supply of the TD-LTE device  110 B. If the power supply of the TD-LTE device  110 B is turned on, the TD-LTE communication processing unit  127   b  obtains a PLMN code at regular intervals, and if the obtained PLMN code is the PLMN code of the specified service provider, the TD-LTE communication processing unit  127   b  establishes a TD-LTE wireless communication. 
         [0067]    On the other hand, if the communication control unit  127   d  receives a determination result indicating that the first PLMN code does not match the PLMN code of the specified Japanese service provider, the communication control unit  127   d  turns off the power supply of the TD-LTE device  110 B. While the power supply of the TD-LTE device  110 B is being turned off, the TD-LTE communication processing unit  127   b  does not carry out the processing for obtaining a PLMN code. 
         [0068]    Subsequently, the processing procedure of the multi-wireless terminal  100  of the embodiment will be described.  FIGS. 10 and 11  are flowcharts illustrating the processing procedure of the multi-wireless terminal of the embodiment. The processing illustrated in  FIGS. 10 and 11  is started, for example, when the power supply of the multi-wireless terminal  100  is turned on. The processing illustrated in  FIGS. 10 and 11  may be carried out at given intervals after the power supply is turned on. 
         [0069]    As illustrated in  FIG. 10 , when the power supply of the multi-wireless terminal  100  is turned on (step S 101 ), the multi-wireless terminal  100  carries out synchronization for UMTS wireless reception (step S 102 ) and then obtains a PLMN code (step S 103 ). The multi-wireless terminal  100  then establishes a UMTS wireless communication (step S 104 ). 
         [0070]    Thereafter, the multi-wireless terminal  100  determines whether the obtained PLMN code is a PLMN code of a specified service provider (step S 105 ). If the PLMN code is not the PLMN code of the specified service provider (step S 105 , No), the multi-wireless terminal  100  turns off the power supply of the TD-LTE device  110 B (step S 106 ) and establishes a UMTS wireless communication (step S 107 ). 
         [0071]    Meanwhile, if the PLMN code is the PLMN code of the specified service provider (step S 105 , Yes), the multi-wireless terminal  100  turns on the power supply of the TD-LTE device  110 B (step S 108 ) and proceeds to step S 109  of  FIG. 11 . 
         [0072]    With reference to  FIG. 11 , the multi-wireless terminal  100  attempts to detect a TD-LTE wireless signal (step S 109 ) and then determines whether the multi-wireless terminal  100  has detected a TD-LTE wireless signal (step S 110 ). 
         [0073]    If the multi-wireless terminal  100  does not detect a TD-LTE wireless signal (step S 110 , No), the multi-wireless terminal  100  resets a search timer (step S 111 ). Upon the counter of the search timer reaching 0, the multi-wireless terminal  100  attempts to detect a TD-LTE wireless signal (step S 112 ) and returns to step S 110 . 
         [0074]    Meanwhile, if the multi-wireless terminal  100  has detected a TD-LTE wireless signal (step S 110 , Yes), the multi-wireless terminal  100  receives a TD-LTE BCCH and obtains a PLMN code (step S 113 ). Thereafter, the multi-wireless terminal  100  determines whether the PLMN code is the PLMN code of the specified service provider (step S 114 ). 
         [0075]    If the PLMN code is not the PLMN code of the specified service provider (step S 114 , No), the multi-wireless terminal  100  proceeds to step S 111 . Meanwhile, if the PLMN code is the PLMN code of the specified service provider (step S 114 , Yes), the multi-wireless terminal  100  establishes a TD-LTE wireless communication (step S 115 ). 
         [0076]    Subsequently, the effects of the multi-wireless terminal  100  of the embodiment will be described. The multi-wireless terminal  100  obtains a PLMN code through the UMTS communication system to determine whether the multi-wireless terminal  100  is used domestically prior to the multi-wireless terminal  100  carrying out wireless communication through the TD-LTE communication system. If the multi-wireless terminal  100  is used overseas, the multi-wireless terminal  100  turns off the power supply of the TD-LTE device  110 B. As the multi-wireless terminal  100  carries out such processing, a situation where the multi-wireless terminal  100  attempts to detect a TD-LTE wireless signal and to establish a communication at regular intervals even if the TD-LTE is not available overseas can be suppressed, which makes it possible to reduce power consumption. 
         [0077]    On the other hand, if the multi-wireless terminal  100  is used domestically, the multi-wireless terminal  100  turns on the power supply of the TD-LTE device  110 B and attempts to establish a wireless communication through the TD-LTE communication system at regular intervals. Accordingly, the multi-wireless terminal  100  can carry out, by priority, wireless communication through the TD-LTE communication system, which has a higher communication speed. 
         [0078]    Furthermore, the multi-wireless terminal  100  determines whether a PLMN code obtained through the UMTS communication system matches any one of the PLMN codes of the respective domestic service providers contained in the PLMN code information  125   a.  If the PLMN code obtained through the UMTS communication system does not match any one of the PLMN codes of the respective domestic service providers, the multi-wireless terminal  100  turns off the power supply of the TD-LTE device  110 B. Accordingly, a situation where the power supply of the TD-LTE device  110 B is accidentally turned off even through the multi-wireless terminal  100  is located domestically can be suppressed. 
         [0079]    Another embodiment will now be described. For example, the specifications of Worldwide Interoperability for Microwave Access (WiMAX) differ for each service provider. Thus, with WiMAX, WiMAX roaming through another service provider is currently not available. Accordingly, if the multi-wireless terminal  100  includes a WiMAX device that carries out communication using WiMAX, the multi-wireless terminal  100  may carry out on/off control of the power supply of the WiMAX device, as in the case of the TD-LTE device  110 B. In other words, if a PLMN code that has been obtained by receiving a UMTS BCCH differs from the PLMN code of the specified domestic service provider, the multi-wireless terminal  100  may control the WiMAX device to turn off the power supply thereof. 
         [0080]    Furthermore, the multi-wireless terminal  100  may hold a TD-LTE roaming list and may carry out on/off control of the power supply of the TD-LTE device  110 B using such a roaming list. For example, if a PLMN code obtained by receiving a UMTS BCCH does not match any one of the codes on the TD-LTE roaming list, the multi-wireless terminal  100  may turn off the power supply of the TD-LTE device  110 B. 
         [0081]    Furthermore, the multi-wireless terminal  100  may be equipped with an evolution-data only (EVDO) device, in place of the UMTS device  110 A. The multi-wireless terminal  100  obtains a PLMN code through EVDO system wireless communication, and if the PLMN code differs from the PLMN code of the specified domestic service provider, the multi-wireless terminal  100  controls the TD-LTE device  110 B to turn off the power supply thereof. 
         [0082]    The various processes described in the embodiments above can be realized by a wireless terminal device executing a program prepared in advance. Hereinafter, an example of a wireless terminal device that executes a program having functions similar to those of the embodiments described above will be described.  FIG. 12  is a diagram for describing the wireless terminal device that executes a control program. 
         [0083]    In  FIG. 12 , a wireless terminal device  200  that executes the control program includes a ROM  210 , a RAM  220 , a processor  230 , an operation unit  240 , a display unit  250 , and a communication unit  260 . The ROM  210  stores in advance a control program that implements functions similar to those of the embodiments described above. Note that the control program may be recorded in a recording medium, in place of the ROM  210 , that can be read by a drive (not illustrated). Such a recording medium may be, for example, a portable recording medium such as a CD-ROM, a DVD disc, a USB memory, and an SD card, a semiconductor memory such as a flash memory, or the like. As illustrated in  FIG. 12 , the control program includes a determination program  210 A and a communication control program  210 B. The determination program  210 A and the communication control program  210 B may be integrated or discrete as appropriate. 
         [0084]    The processor  230  loads the determination program  210 A and the communication control program  210 B from the ROM  210  and executes the loaded determination program  210 A and communication control program  210 B. Thus, the processor  230  causes the determination program  210 A and the communication control program  210 B to function as a determination process  230 A and a communication control process  230 B, respectively. The determination process  230 , for example, corresponds to the determination unit  127   c  illustrated in  FIG. 3 . The communication control process  230 B, for example, corresponds to the communication control unit  127   d.  The communication unit  260  includes a multi-wireless communication function through multiple communication systems including the LTE system. 
         [0085]    All examples and conditional language recited herein are intended for pedagogical purposes to aid the reader in understanding the invention and the concepts contributed by the inventor to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions, nor does the organization of such examples in the specification relate to a showing of the superiority and inferiority of the invention. Although the embodiments of the present invention have been described in detail, it should be understood that the various changes, substitutions, and alterations could be made hereto without departing from the spirit and scope of the invention.