JP5033659B2 - Wireless communication apparatus and wireless communication method - Google Patents

Description

  The present invention relates to a wireless communication apparatus that is operated by a battery and can be connected to a plurality of wireless communication networks, and a wireless communication method used in the wireless communication apparatus.

  In recent years, with the advancement of wireless communication technology, a wireless communication device that can be connected to a plurality of wireless communication networks with different communication methods has been proposed (for example, Patent Document 1). A wireless communication device (for example, a mobile communication terminal) that can be connected to a plurality of wireless communication networks as described above generally operates on a battery and has a plurality of network connection units (corresponding to the number of connectable wireless communication networks) ( For example, mobile phone network and wireless LAN). Each network connection unit generally includes a power amplifier that amplifies a radio signal.

When performing a handover from a connected wireless communication network to another wireless communication network, the wireless communication device uses a wireless signal transmitted / received to / from a connected wireless communication network, that is, a wireless communication network that is a handover source. The power amplifier of the connection unit and the power amplifier of the network connection unit used for transmission / reception of radio signals with the handover destination radio communication network are activated simultaneously. For this reason, the wireless communication apparatus can execute a so-called soft handover that executes a handover while minimizing the time during which the ongoing communication is interrupted.
JP 2007-266987 A (page 9-10, FIG. 1)

  However, the above-described conventional wireless communication apparatus has the following problems. That is, when the wireless communication apparatus performs soft handover, the wireless communication apparatus transmits / receives a radio signal between the power amplifier used for transmission / reception of the radio signal with the handover source radio communication network and the radio communication network of the handover destination. Since the power amplifier used is activated at the same time, there is a problem that the output voltage of the battery driving the power amplifier drops.

  Specifically, if multiple power amplifiers are driven using a battery whose output voltage has already dropped since the end of charging as a result of being used for a certain period of time after charging, the output voltage is reduced to the voltage at which the protection circuit operates. May fall. When the output voltage drops to a voltage at which the protection circuit operates, the ongoing communication is interrupted.

  Therefore, the present invention has been made in view of such a situation, and provides a wireless communication device and a wireless communication method capable of suppressing the interruption of communication being performed at the time of handover due to a drop in the output voltage of the battery. With the goal.

In order to solve the problems described above, the present invention has the following features. First, the first feature of the present invention is that a wireless communication device (wireless communication device 100) that operates by a battery (battery 119) and can be connected to a plurality of wireless communication networks (wireless communication network 1 to wireless communication network 3). And a network connection unit (network connection unit 101 ₁ to network connection unit 101 ₃ ) that connects to the wireless communication network using a wireless signal (wireless signal RS), and a wireless communication network that is currently connected (for example, wireless A handover control unit (handover control unit 107) that controls a handover from the communication network 1) to another radio communication network (for example, the radio communication network 2), and an output voltage (output voltage Vy) output from the battery are detected. A voltage detector (battery voltage monitor 121); A voltage drop amount acquisition unit (battery voltage monitor) for acquiring the output voltage drop amount (for example, the drop amount Vd) when the network connection unit is connected to one or a plurality of the wireless communication networks used in the handover. Unit 121), and when the predicted voltage (predicted voltage Vexp) obtained by subtracting the drop amount from the output voltage is equal to or lower than a predetermined threshold (threshold voltage Vthld or lower limit voltage Vlmt), the other wireless communication network by the handover control unit And an operation control unit (operation control unit 109) for canceling the execution of the handover.

  According to such a wireless communication apparatus, when the predicted voltage obtained by subtracting the voltage drop amount associated with the execution of the handover from the output voltage is equal to or lower than a predetermined threshold value, a handover to another wireless communication network (for example, soft handover) is performed. Canceled. For this reason, it is possible to prevent the ongoing communication from being interrupted when the output voltage drops to the voltage at which the protection circuit operates.

  A second feature of the present invention relates to the first feature of the present invention, wherein it is determined whether or not a quality (for example, RSSI) of the radio signal or information included in the radio signal is deteriorated from a predetermined condition. A quality determination unit (communication quality determination unit 105) that performs the handover by the handover control unit when the quality determination unit determines that the quality has deteriorated below the predetermined condition. The gist of this is to determine whether or not to stop the execution.

  A third feature of the present invention relates to the first or second feature of the present invention, wherein the operation control unit is configured such that the output voltage detected by the voltage detection unit is equal to or lower than a predetermined value (determination start voltage Vs). In this case, the gist is to determine whether or not to stop execution of the handover by the handover control unit.

  A fourth feature of the present invention relates to the first feature of the present invention, and is used in a wireless communication apparatus that is operated by a battery and includes a network connection unit that can be connected to a plurality of wireless communication networks using wireless signals. A method of controlling a handover from a connected wireless communication network to another wireless communication network, a step of detecting an output voltage output from the battery, and one or more used in the handover A step of obtaining a drop amount of the output voltage when the network connection unit is connected to a plurality of the wireless communication networks, and a predicted voltage obtained by subtracting the drop amount from the output voltage is equal to or less than a predetermined threshold, Canceling execution of handover to another wireless communication network; and And summarized in that provided.

  According to the features of the present invention, it is possible to provide a wireless communication apparatus and a wireless communication method capable of suppressing the interruption of communication being performed at the time of handover due to a drop in the output voltage of the battery.

  Next, an embodiment of the present invention will be described. Specifically, (1) overall schematic configuration of communication network, (2) functional block configuration of wireless communication device, (3) operation of wireless communication device, (4) action / effect, and (5) other embodiments Will be described.

  In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic and ratios of dimensions and the like are different from actual ones.

  Accordingly, specific dimensions and the like should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

(1) Overall Schematic Configuration of Communication Network FIG. 1 is an overall schematic configuration diagram of a communication network according to the present embodiment. As shown in FIG. 1, in the present embodiment, a wireless communication network 1, a wireless communication network 2, and a wireless communication network 3 constitute a communication network. The wireless communication network 1, the wireless communication network 2, and the wireless communication network 3 use different communication methods.

  The wireless communication network 1 is, for example, a mobile phone network (for example, cdma2000) that uses the cdma method. The wireless communication network 2 conforms to, for example, mobile WiMAX defined in IEEE802.16E. The wireless communication network 3 conforms to, for example, a wireless LAN defined in IEEE802.11g.

  The wireless communication network 1, the wireless communication network 2, and the wireless communication network 3 include a wireless base station 11, a wireless base station 12, and a wireless base station 13 that transmit and receive a wireless signal RS to and from the wireless communication device 100.

  The wireless communication device 100 can be connected to a plurality of wireless communication networks, specifically, the wireless communication network 1, the wireless communication network 2, and the wireless communication network 3 using the wireless signal RS. In the present embodiment, the wireless communication device 100 is a portable small wireless communication terminal. The wireless communication device 100 is operated by a battery 119 (not shown in FIG. 1, refer to FIG. 2).

(2) Functional Block Configuration of Radio Communication Device Next, a functional block configuration of the radio communication device 100 will be described with reference to FIGS. 2 and 3.

(2.1) Overall Block Configuration FIG. 2 is a functional block configuration diagram of the wireless communication device 100. As illustrated in FIG. 2, the wireless communication device 100 includes a network connection unit 101 ₁ , a network connection unit 101 ₂ , a network connection unit 101 ₃ , a modem unit 104, a communication quality determination unit 105, a handover control unit 107, and an operation control unit 109. , An application 111, a speaker 113, a microphone 115, and a display unit 117.

  Hereinafter, portions related to the present invention will be mainly described. Therefore, it should be noted that the wireless communication device 100 may include blocks that are not illustrated or omitted in the description that are essential for realizing the functions of the wireless communication device 100.

  The wireless communication device 100 also includes a battery 119 that supplies power to each functional block. Furthermore, the wireless communication device 100 includes a battery voltage monitor unit 121, a battery voltage drop table storage unit 123, and a power supply control unit 130 in order to control the operation of the wireless communication device 100 related to the battery 119.

The network connection unit 101 _1, a wireless communication network 1 by using a radio signal RS (cdma2000), specifically, to provide a communication interface for connecting to the wireless base station 11.

The network connection unit 101 _2, a wireless communication network 2 by using the radio signal RS (Mobile WiMAX), specifically, to provide a communication interface for connecting to the radio base station 12.

The network connection unit 101 _3, a wireless communication network 3 by using a radio signal RS (wireless LAN), specifically, to provide a communication interface for connecting to the radio base station 13.

The modulation / demodulation unit 104 executes modulation processing of IP packets output from the application 111 and demodulation processing of signals output from the network connection unit 101 ₁ to the network connection unit 101 ₃ .

  The communication quality determination unit 105 acquires the communication quality (for example, RSSI) of the radio signal RS and the quality of information (for example, an IP packet output from the application 111) included in the radio signal RS.

  Further, the communication quality determination unit 105 determines whether or not the acquired communication quality has deteriorated from a predetermined condition. In particular, in this embodiment, the communication quality determination unit 105 determines the communication quality of the radio signal RS based on three types of communication quality deterioration conditions. Specifically, the communication quality determination unit 105 determines the communication quality of the radio signal RS based on the first quality deterioration condition, the second quality deterioration condition, and the third quality deterioration condition.

  The first quality degradation condition corresponds to the communication quality to be handed over to another wireless communication network. The second quality degradation condition corresponds to the communication quality to be prepared for handover to another wireless communication network. The third quality deterioration condition corresponds to the communication quality at which the determination of the drop amount Vd of the output voltage Vy of the battery 119 accompanying the handover to another wireless communication network should be started.

  That is, among the communication qualities corresponding to the first quality deterioration condition to the third quality deterioration condition, the communication quality corresponding to the third quality deterioration condition is the best, and the communication quality corresponding to the first quality deterioration condition is the worst. It is.

  The handover control unit 107 controls a handover from a connected wireless communication network (for example, the wireless communication network 1) to another wireless communication network (for example, the wireless communication network 2).

  The handover control unit 107 includes a plurality of parameters, specifically, communication quality of the radio signal RS (and information included in the radio signal RS), QoS threshold of the application (usable communication band (communication speed), propagation delay, etc.) And whether or not to execute handover to another wireless communication network based on the charging system associated with the use of the wireless communication network.

  Further, in the present embodiment, the handover control unit 107 uses the amount of decrease Vd of the output voltage Vy of the battery 119 accompanying the handover to another wireless communication network as a parameter for determining whether or not to execute the handover.

  The operation control unit 109 controls the operation of the wireless communication device 100. In particular, in the present embodiment, the operation control unit 109 controls whether or not to execute the handover based on the drop amount Vd of the output voltage Vy of the battery 119 associated with the handover to another wireless communication network.

  Specifically, based on the information notified from the battery voltage monitor unit 121, the operation control unit 109 calculates the drop amount Vd of the output voltage Vy accompanying the handover to another wireless communication network as the current output voltage of the battery 119. It is determined whether or not the predicted voltage Vexp subtracted from Vy is equal to or lower than a threshold voltage Vthld (predetermined threshold).

  When the predicted voltage Vexp is equal to or lower than the threshold voltage Vthld and exceeds the lower limit voltage Vlmt, the operation control unit 109 performs a handover to another wireless communication network by the handover control unit 107, specifically, a soft handover. In addition, the operation control unit 109 stops the execution of the soft handover when the predicted voltage Vexp is equal to or lower than the lower limit voltage Vlmt. Further, when the predicted voltage V′exp when the operation control unit 109 is connected only to another wireless communication network is equal to or lower than the lower limit voltage Vlmt, the handover control unit 107 performs handover to another wireless communication network, specifically The execution of hard handover is stopped.

  In the present embodiment, the operation control unit 109 executes the handover by the handover control unit 107 when the communication quality determination unit 105 determines that the communication quality has deteriorated from the third quality deterioration condition (predetermined condition). The determination of whether or not to cancel can be started. That is, the operation control unit 109 does not determine whether or not the predicted voltage Vexp is equal to or lower than the threshold voltage Vthld when the communication quality is not deteriorated below the third quality deterioration condition.

  Further, when the output voltage Vy detected by the battery voltage monitor unit 121 is equal to or lower than the determination start voltage Vs (predetermined value), the operation control unit 109 determines whether or not to stop the handover execution by the handover control unit 107. You can also start.

Here, FIG. 7 shows an example of a change in the output voltage Vy as the battery 119 is consumed. Discharge curve P1 represents the change in status of the output voltage Vy when the power amplifier 103 of the network connection unit 101 ₁ 1 _(see FIG. 3) to turn on. A discharge curve P2 shows a change state of the output voltage Vy when all of the network connection units 101 ₁ to 101 ₃ are turned off. Discharge curve P3 shows the change status of the output voltage Vy when network connection unit 101 ₁ of the power amplifier 103 ₁ and the power amplifier 103 of the network connection unit 101 _{2 2} (see FIG. 3) to turn on.

  The lower limit voltage Vlmt is a voltage (3.4V) at which a protection circuit (not shown) operates. The lower limit voltage Vlmt may be a voltage slightly higher than the voltage at which the protection circuit operates. As shown in FIG. 7, the wireless communication device 100 can be simultaneously connected to the wireless communication network 1 and the wireless communication network 2 only at a time point before the start point (3.47 V) of the section S. Therefore, in the present embodiment, the threshold voltage Vthld is set to 3.6 V, which is 200 mV higher than the lower limit voltage Vlmt. The determination start voltage Vs is set to 3.9V.

  The application 111 is configured by an application program (for example, a voice call application using VoIP) that realizes a function provided by the wireless communication apparatus 100.

  The speaker 113 outputs a predetermined audible band signal based on the control of the application 111 and the operation control unit 109. In particular, in the present embodiment, when the predicted voltage Vexp calculated by the operation control unit 109 is determined to be lower than the lower limit voltage Vlmt, the speaker 113 cannot execute a handover to another wireless communication network. It is possible to output a warning sound notifying the user of the wireless communication device 100 that the ongoing communication may be interrupted.

  The microphone 115 converts the input voice or the like into an electrical signal and outputs it to the application 111.

  The display unit 117 is configured by a small liquid crystal display. An image is displayed based on the control of the application 111 or the operation control unit 109.

  The battery 119 supplies power necessary for the operation of each functional block constituting the wireless communication apparatus 100. In the present embodiment, the battery 119 is configured by a cell lithium ion battery.

The battery voltage monitor unit 121 monitors the output voltage Vy output from the battery 119 and the amount of decrease Vd of the output voltage Vy accompanying the activation of the network connection unit at the time of handover to another wireless communication network. Specifically, the battery voltage monitor unit 121 outputs the output voltage Vy when any or all of the network connection unit 101 ₁ to the network connection unit 101 ₃ are connected to one or a plurality of wireless communication networks used in the handover. Get the descent amount Vd. In the present embodiment, the battery voltage monitor unit 121 configures a voltage detection unit and a voltage drop amount acquisition unit.

  The battery voltage drop table storage unit 123 stores a battery voltage drop table TB (see FIG. 6) referred to by the battery voltage monitor unit 121. As shown in FIG. 6, the battery voltage drop table TB is configured by the output voltage Vy and the drop amount Vd of the output voltage Vy when connected to each wireless communication network.

For example, when the output voltage Vy is 3.9V, drop Vd when you start the network connection unit 101 ₁ in order to connect to the wireless communication network 1 is a 0.13 V. That is, it means that the output voltage Vy drops to 3.77V (3.9V-0.13V). Furthermore, in order to perform the so-called soft handover, drop Vd for output voltage 3.77V in the case where in addition to the network connection unit 101 ₁ to start the network connection unit 101 _2, 0.17 V (battery output of the battery voltage drop table TB Voltage = see 3.7V).

  Further, when a plurality of network connection units are activated simultaneously, it is also possible to make a determination using the sum of the respective drop amounts Vd with respect to the output voltage of the battery at that time.

  Note that the factor that the output voltage Vy falls exists in addition to the activation of the network connection unit (power amplifier), but in this embodiment, the factor that causes the output voltage Vy to fall is dominated by the activation of the power amplifier. As an example, a battery voltage drop table TB indicating a drop amount Vd depending on whether or not a plurality of network connections (power amplifiers) are activated is prepared.

  The power supply control unit 130 performs voltage conversion for detecting the voltage of the battery 119 by the A / D converter 112.

(2.2) Functional Block Configuration Regarding Transmission Power Control FIG. 3 is a functional block configuration diagram regarding transmission power control of power amplifiers provided in the network connection units 101 ₁ to 101 ₃ , respectively.

As illustrated in FIG. 3, the network connection unit 101 ₁ includes a power switch 102 ₁ and a power amplifier 103 ₁ . Similarly, the network connection unit 101 ₂ (network connection unit 101 ₃ ) includes a power switch 102 ₂ (power switch 102 ₃ ) and a power amplifier 103 ₂ (power amplifier 103 ₃ ).

  The power supply control unit 130 is connected to the power supply line of the battery 119, and executes voltage conversion for detecting the battery voltage by the A / D converter 112. The power control unit 130 is configured by a power control IC or the like.

  The battery voltage monitor unit 121 detects the output voltage Vy output from the power supply control unit 130. The battery voltage monitor unit 121 converts the detected voltage into a digital signal by the A / D converter 112, and an output accompanying the activation of the network connection unit at the time of handover to another wireless communication network based on the converted output voltage Vy. Monitor the drop Vd of voltage Vy.

  Based on the information notified from the battery voltage monitor unit 121, that is, the amount of decrease Vd in the output voltage Vy, the operation control unit 109 determines whether or not to execute handover to another wireless communication network. Instruct.

Handover control unit 107, based on an instruction from the operation control unit 109 determines whether to activate the power amplifier 103 ₁ to the power amplifier 103 _3.

(3) Operation of Wireless Communication Device Next, the operation of the wireless communication device 100 will be described. Specifically, an operation for controlling whether or not the wireless communication device 100 executes a handover to another wireless communication network based on the drop amount Vd of the output voltage Vy of the battery 119 will be described.

  4 and 5 are flowcharts showing a handover operation to another wireless communication network by the wireless communication apparatus 100. FIG.

  As shown in FIG. 4, in step S10, the wireless communication device 100 checks the output voltage Vy of the battery 119.

  In step S <b> 20, the wireless communication apparatus 100 determines whether communication is being performed by connecting to the wireless communication network 1.

  When connected to the wireless communication network 1 and not performing communication (NO in step S20), in step S30, the wireless communication device 100 proceeds to a process of confirming a connection state with another wireless communication network. Even when connected to another wireless communication network (wireless communication network 2 or wireless communication network 3), the wireless communication device 100 performs the same operation as the flow shown in FIG. 4 and FIG. A case where the wireless communication network 1 is connected will be described as an example.

  When communication is being executed while connected to the wireless communication network 1 (YES in step S20), the wireless communication device 100 determines that the communication quality of the wireless signal RS (or information included in the wireless signal RS) is the first in step S40. It is determined whether or not one quality deterioration condition is satisfied.

  If the communication quality does not satisfy the first quality degradation condition (NO in step S40), in step S50, the radio communication device 100 determines whether the communication quality of the radio signal RS satisfies the second quality degradation condition. .

  When the communication quality satisfies the second quality deterioration condition (YES in step S50), in step S60, the wireless communication device 100 determines the state of a flag indicating whether or not handover to another wireless communication network is possible. Specifically, the wireless communication device 100 sets the contents of a flag (Fho_nw2_ng = 1) indicating whether handover to the wireless communication network 2 is possible and a flag (Fho_nw3_ng = 1) indicating whether handover to the wireless communication network 3 is possible. Check. The wireless communication apparatus 100 determines whether Fho_nw2_ng = 1 and Fho_nw3_ng = 1.

  For example, Fho_nw2_ng = 1 indicates that handover to the wireless communication network 2 is impossible. On the other hand, Fho_nw2_ng = 0 indicates that a handover to the wireless communication network 2 is possible. The state of the flag is set based on the determination result of the drop amount Vd of the output voltage Vy of the battery 119.

  If Fho_nw2_ng = 1 and Fho_nw3_ng = 1 are not satisfied (NO in step S60), that is, if handover to any wireless communication network is possible, in step S70, the wireless communication device 100 performs soft handover to the wireless communication network. The state of the flag indicating whether or not can be executed is determined.

  Specifically, the wireless communication device 100 does not perform a soft handover that connects to a plurality of wireless communication networks at the same time, but performs a so-called hard handover that disconnects a connected wireless communication network and then connects to a handover destination wireless communication network. Check the contents of the flag (Fmake_after_break = 1) indicating that it should be executed.

  If it is not indicated that hard handover should be executed (NO in step S70), that is, if soft handover can be executed, in step S80, the wireless communication device 100 is connected to the wireless communication network 2 or the wireless communication network 3. To prepare for handover.

  When the communication quality does not satisfy the second quality degradation condition (NO in step S50), in step S90, the radio communication device 100 determines whether the communication quality of the radio signal RS satisfies the third quality degradation condition. .

  When the communication quality satisfies the third quality deterioration condition (YES in step S90), in step S100, the radio communication device 100 determines whether the handover candidate is the radio communication network 2.

  When the handover candidate is the wireless communication network 2 (YES in step S100), in step S110, the wireless communication device 100 determines that the allowable communication interruption time Tpmtdwn associated with the handover is the time required for connection with the wireless communication network 2 associated with the handover Tcnct. It is determined whether it is longer.

  When the communication disconnection allowable time Tpmtdwn is longer than the connection required time Tcnct (YES in step S110), in step S120, the radio communication device 100 sets a flag (Fmake_after_break = 1) indicating that hard handover should be executed.

  When the allowable communication interruption time Tpmtdwn is shorter than the required connection time Tcnct (NO in step S110), in step S130, the wireless communication device 100 sets a flag (Fmake_after_break = 0) indicating that soft handover should be executed.

  In step S <b> 140, the wireless communication device 100 calculates a drop amount Vz of the output voltage Vy of the battery 119 when connected to the wireless communication network 2 when using the wireless communication network 1. For example, when the output voltage Vy is 3.7 V, a drop amount Vz (0.17 V) associated with connection to the wireless communication network 2 is calculated as shown in FIG.

  In step S150, the wireless communication device 100 determines whether or not the predicted voltage Vexp (Vy−Vz) obtained by subtracting the drop amount Vz from the output voltage Vy is equal to or lower than the threshold voltage Vthld.

  When the predicted voltage Vexp is equal to or lower than the threshold voltage Vthld (YES in step S150), in step S160, the wireless communication device 100 determines whether the predicted voltage Vexp is higher than the lower limit voltage Vlmt.

  When the predicted voltage Vexp is higher than the lower limit voltage Vlmt (YES in step S160), in step S170, after connecting to the wireless communication network 2, the wireless communication device 100 executes handover, that is, executes soft handover.

  When the predicted voltage Vexp is lower than the lower limit voltage Vlmt (NO in step S160), in step S180, the wireless communication device 100 calculates the drop amount Vd2 of the output voltage Vy when connected to the wireless communication network 2 only.

  In step S190, the wireless communication device 100 adds the voltage obtained from the value (Vy + Vd1) obtained by adding the drop amount Vd1 when only the wireless communication network 1 is connected to the output voltage Vy when the wireless communication network 1 is connected. It is determined whether or not the value obtained by subtracting the drop amount Vd2 when only connected to the wireless communication network 2 corresponding to is higher than the lower limit voltage Vlmt.

  When the value obtained by subtracting the drop amount Vd2 from the value obtained by adding the drop amount Vd1 to the output voltage Vy is higher than the lower limit voltage Vlmt (YES in step S190), in step S200, the radio communication device 100 should execute hard handover. Set a flag (Fmake_after_break = 1) to indicate this.

  When the value obtained by subtracting the drop amount Vd2 from the value obtained by adding the drop amount Vd1 to the output voltage Vy is lower than the lower limit voltage Vlmt (NO in step S190), in step S210, the wireless communication device 100 connects to the wireless communication network 2. A flag (Fho_nw2_ng = 1) indicating that a handover is impossible is set. Further, the radio communication device 100 changes the handover candidate to the radio communication network 3.

  If the handover candidate is not the wireless communication network 2 (NO in step S100), that is, if the handover candidate is the wireless communication network 3, in step S220, the wireless communication device 100 determines that the allowable communication disconnection time Tpmtdwn is greater than the connection required time Tcnct. It is determined whether it is too long. Note that the processing in steps S220 to S240 is the same as the processing in steps S110 to S130.

  In step S <b> 250, the wireless communication device 100 calculates the amount of decrease Vr of the output voltage Vy of the battery 119 when connected to the wireless communication network 3 when using the wireless communication network 1. For example, when the output voltage Vy is 3.7 V, a drop amount Vr (0.19 V) associated with connection to the wireless communication network 3 is calculated as shown in FIG.

  In step S260, the wireless communication device 100 determines whether or not the predicted voltage Vexp (Vy−Vr) obtained by subtracting the drop amount Vr from the output voltage Vy is equal to or lower than the threshold voltage Vthld.

  When the predicted voltage Vexp is equal to or lower than the threshold voltage Vthld (YES in step S260), in step S270, the wireless communication device 100 determines whether the predicted voltage Vexp is higher than the lower limit voltage Vlmt.

  When the predicted voltage Vexp is higher than the lower limit voltage Vlmt (YES in step S270), in step S280, the radio communication device 100 executes handover after connecting to the radio communication network 2, that is, executes soft handover.

  When the predicted voltage Vexp is lower than the lower limit voltage Vlmt (NO in step S270), in step S290, the wireless communication device 100 decreases the output voltage Vy when the wireless communication device 100 is connected only to the wireless communication network 3. Calculate Vd3.

  In step S300, the wireless communication device 100 adds the voltage obtained from the value (Vy + Vd1) obtained by adding the drop amount Vd1 when the wireless communication device 1 is connected only to the wireless communication network 1 to the output voltage Vy when the wireless communication network 1 is connected. It is determined whether or not the value obtained by subtracting the drop amount Vd3 when connected only to the wireless communication network 3 corresponding to is higher than the lower limit voltage Vlmt.

  When the value obtained by subtracting the drop amount Vd3 from the value obtained by adding the drop amount Vd1 to the output voltage Vy is higher than the lower limit voltage Vlmt (YES in step S300), in step S310, the radio communication device 100 should execute hard handover. Set a flag (Fmake_after_break = 1) to indicate this.

  When the value obtained by subtracting the drop amount Vd3 from the value obtained by adding the drop amount Vd1 to the output voltage Vy is lower than the lower limit voltage Vlmt (NO in step S300), in step S320, the wireless communication device 100 connects to the wireless communication network 3. A flag (Fho_nw3_ng = 1) indicating that handover is impossible is set. Further, the radio communication device 100 changes the handover candidate to the radio communication network 1.

  As shown in FIG. 5, when the communication quality satisfies the first quality deterioration condition (YES in step S40 in FIG. 4), in step S410, the radio communication apparatus 100 determines whether or not handover to another radio communication network is possible. The state of the indicated flag is determined. Specifically, the wireless communication device 100 sets the contents of a flag (Fho_nw2_ng = 1) indicating whether handover to the wireless communication network 2 is possible and a flag (Fho_nw3_ng = 1) indicating whether handover to the wireless communication network 3 is possible. Check. The wireless communication apparatus 100 determines whether Fho_nw2_ng = 1 and Fho_nw3_ng = 1.

  When Fho_nw2_ng = 1 and Fho_nw3_ng = 1 (YES in step S410), in step S420, the wireless communication device 100 determines not to execute another wireless communication network.

  If Fho_nw2_ng = 1 and Fho_nw3_ng = 1 are not satisfied (NO in step S410), that is, if handover to any wireless communication network is possible, in step S430, the wireless communication device 100 performs a hard handover. Check the contents of the indicated flag (Fmake_after_break = 1).

  If it is not indicated that hard handover should be performed (NO in step S430), that is, if soft handover can be performed, in step S440, the wireless communication device 100 maintains the connection of the wireless communication network 1, A handover to the wireless communication network 2 or the wireless communication network 3 is executed.

  If it is indicated that hard handover is to be executed (YES in step S430), the wireless communication device 100 disconnects the wireless communication network 1 in step S450.

  In step S460, the wireless communication device 100 is connected to the wireless communication network 2 or the wireless communication network 3.

  In step S <b> 470, the wireless communication device 100 performs a handover to the wireless communication network 2 or the wireless communication network 3.

(4) Operation / Effect According to the wireless communication device 100, when the predicted voltage Vexp obtained by subtracting the voltage drop amount Vd accompanying the execution of the handover from the output voltage Vy is equal to or lower than the threshold voltage Vthld and exceeds the lower limit voltage Vlmt, A handover to another wireless communication network, specifically, a soft handover is executed. Further, when the predicted voltage Vexp is equal to or lower than the lower limit voltage Vlmt, the execution of soft handover is stopped. For this reason, it is possible to prevent the ongoing communication from being interrupted when the output voltage drops to the voltage at which the protection circuit operates.

  In this embodiment, the operation control unit 109 suspends execution of the handover by the handover control unit 107 when the communication quality determination unit 105 determines that the communication quality of the radio signal RS has deteriorated from the third quality deterioration condition. It is determined whether or not. For this reason, it is determined whether or not to cancel the handover by the handover control unit 107 only when the communication quality of the radio signal RS is deteriorated and the possibility that the handover is executed is high. That is, since the communication quality of the radio signal RS is good and the possibility that the handover is executed is low, the determination process can be stopped, so that the processing load can be reduced and the power can be saved.

  In the present embodiment, when the output voltage Vy detected by the battery voltage monitor unit 121 is equal to or lower than the determination start voltage Vs, the operation control unit 109 determines whether or not to stop the handover execution by the handover control unit 107. That is, when the output voltage Vy of the battery 119 is sufficiently high, the output voltage Vy does not reach the lower limit voltage Vlmt even if a soft handover to another wireless communication network is executed. For this reason, if the output voltage Vy does not reach the lower limit voltage Vlmt even after executing the soft handover, the determination process can be stopped, so that the processing load can be reduced and the power can be saved.

(5) Other Embodiments As described above, the content of the present invention has been disclosed through one embodiment of the present invention. However, it is understood that the description and drawings constituting a part of this disclosure limit the present invention. should not do. From this disclosure, various alternative embodiments will be apparent to those skilled in the art.

  For example, in the above-described embodiment, when the output voltage Vy exceeds the determination start voltage Vs and when the quality of the radio signal RS is better than the third quality deterioration condition, whether or not the handover by the handover controller 107 is stopped. The determination is not made, but the determination may be always performed regardless of the quality of the output voltage Vy or the radio signal RS.

  In the above-described embodiment, the battery voltage drop table TB is stored in the battery voltage drop table storage unit 123 in advance. However, the value of the drop amount Vd of the output voltage Vy is generated and updated based on the actual measurement result. You may be made to do.

  As described above, the present invention naturally includes various embodiments that are not described herein. Therefore, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

1 is an overall schematic configuration diagram of a communication network according to an embodiment of the present invention. It is a functional block block diagram of the radio | wireless communication apparatus 100 which concerns on embodiment of this invention. It is a functional block block diagram regarding transmission power control of the power amplifier provided in each of the network connection unit 101 ₁ to the network connection unit 101 _{3 according} to the embodiment of the present invention. It is a flowchart which shows the hand-over operation to the other radio | wireless communication network by the radio | wireless communication apparatus 100 which concerns on embodiment of this invention. It is a flowchart which shows the hand-over operation to the other radio | wireless communication network by the radio | wireless communication apparatus 100 which concerns on embodiment of this invention. It is a figure which shows an example of the battery voltage drop table TB which concerns on embodiment of this invention. It is a figure which shows the example of a change of the output voltage Vy accompanying the consumption of the battery 119 which concerns on embodiment of this invention.

Explanation of symbols

1-3 ... wireless communication networks, 11 to 13 ... radio base station, 100 ... wireless communication _device, 101 1 to 101 3 _... network connection _unit, 102 1 to 102 3 _... power _switch, 103 1 to 103 3 _... power amplifier, DESCRIPTION OF SYMBOLS 104 ... Modulation / demodulation part, 105 ... Communication quality determination part, 107 ... Handover control part, 109 ... Operation control part, 111 ... Application, 112 ... A / D converter, 113 ... Speaker, 115 ... Microphone, 117 ... Display part, 119 ... Battery: 121 ... Battery voltage monitor unit, 123 ... Battery voltage drop table storage unit, 130 ... Power supply control unit, P1-P3 ... Discharge curve, RS ... Radio signal, S ... Section, TB ... Battery voltage drop table

Claims (4)

A wireless communication device that is operated by a battery and can be connected to a plurality of wireless communication networks,
A network connection unit for connecting to the wireless communication network using a wireless signal;
A handover control unit for controlling a handover from a connected wireless communication network to another wireless communication network;
A voltage detector for detecting an output voltage output from the battery;
A voltage drop amount acquisition unit for acquiring a drop amount of the output voltage when the network connection unit is connected to one or a plurality of the wireless communication networks used in the handover;
A radio communication apparatus comprising: an operation control unit that suspends execution of a handover to the other radio communication network by the handover control unit when a predicted voltage obtained by subtracting the drop amount from the output voltage is a predetermined threshold value or less. A quality determination unit that determines whether or not the quality of the radio signal or the information included in the radio signal is deteriorated below a predetermined condition;
The operation control unit determines whether or not to stop the execution of the handover by the handover control unit when the quality determination unit determines that the quality has deteriorated from the predetermined condition. The wireless communication device described.   3. The operation control unit according to claim 1, wherein when the output voltage detected by the voltage detection unit is equal to or lower than a predetermined value, the operation control unit determines whether to stop the execution of the handover by the handover control unit. Wireless communication device. A wireless communication method used in a wireless communication device including a network connection unit that operates by a battery and can be connected to a plurality of wireless communication networks using wireless signals,
Controlling handover from a connected wireless communication network to another wireless communication network;
Detecting an output voltage output by the battery;
Obtaining a drop amount of the output voltage when the network connection unit is connected to one or a plurality of the wireless communication networks used in the handover;
And a step of canceling execution of the handover to the other wireless communication network when a predicted voltage obtained by subtracting the drop amount from the output voltage is equal to or less than a predetermined threshold.

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