Communication apparatus for use in a master/slave communication network

0001The present invention relates to a communication apparatus that is used as a terminal in a communication network, such as a piconet according to Bluetooth technology, wherein one of a plurality of terminals acts as a master and the other(s) as slave(s), thereby executing communication between the terminals.

0002In Bluetooth, in a state in which a connectable device is not found, a standby operation by Inquiry/Page_Scan is executed. If the Inquiry/Page_Scan is always executed, however, a current consumption would increase.

0003Jpn. Pat. Appln. KOKAI Publication No. 2003-37545, for instance, discloses a technique that is available in order to overcome this drawback. According to this technique of <patcit id="pcit0001" dnum="JP2003037545A"><text>Japanese KOKAI 2003-37545</text></patcit>, if an interrupt due to reception of an incoming signal or a key operation does not occur during a predetermined time period, a short-distance wireless function is turned off, thereby reducing power consumption.

0004The technique of <patcit id="pcit0002" dnum="JP2003037545A"><text>Japanese KOKAI 2003-37545</text></patcit>, however, completely disables the short-distance wireless function. In this case, the standby operation is also disabled. Consequently, even if a connectable device is present nearby, this connectable device cannot be detected.

0005Under the circumstances, there is a demand for a technique that makes it possible to carry out a search for a connectable device, while reducing power consumption that is needed for the search operation.

0006In <patcit id="pcit0003" dnum="WO02089391A"><text>WO 02/089391</text></patcit> there is disclosed a method by which a new Bluetooth piconet is established among participants of an old Bluetooth piconet whose master has disappeared. After determining that the master has disappeared, one of the slaves is selected to take the function of the master and re-establishes communications at the baseband layer by contacting each of the other participants.

0007According to an aspect of the present invention, there is provided a communication apparatus that is used as a terminal in a communication network wherein one of a plurality of terminals acts as a master and the other(s) as slave(s), thereby executing communication between the terminals, comprising: detection means (9) for detecting a first signal that is sent from the terminal acting as the master in order to call the communication apparatus; halt means for halting the detection means (9) upon non-detection of the first signal during a first time period; transmission means for transmitting a second signal in order to inquire of or page the terminals; start means for causing the transmission means to start transmission of the second signal, upon passage of a second time period from the halt of the detection means (9); means for issuing a request for a master/slave role switch to a said terminal that responds to the second signal transmitted from the transmission means; and means for executing the master/slave role switch upon acceptance of the request.

0008This summary of the invention does not necessarily describe all necessary features so that the invention may also be a sub-combination of these described features.

0009The invention can be more fully understood from the following detailed description when taken in conjunction with the accompanying drawings, in which: <ul id="ul0001" list-style="none" compact="compact"><li><figref idref="f0001">FIG. 1</figref> is a block diagram showing the structure of a wireless communication apparatus according to an embodiment of the present invention;</li><li><figref idref="f0002">FIG. 2</figref> is a flow chart illustrating procedures of a BT (Bluetooth) control that is executed by a control section in <figref idref="f0001">FIG. 1</figref>; and</li><li><figref idref="f0003">FIG. 3</figref> is a flow chart illustrating procedures of a user setting process by the control section in <figref idref="f0001">FIG. 1</figref>.</li></ul>

0010An embodiment of the present invention will now be described with reference to the accompanying drawings.

0011<figref idref="f0001">FIG. 1</figref> is a block diagram showing the structure of a wireless communication apparatus according to the embodiment. This wireless communication apparatus is used as a mobile station of a mobile wireless communication system according to a W-CDMA (Wideband-Code Division Multiple Access) scheme that is stipulated by 3GPP (3rd Generation Partnership Project).

0012The wireless communication apparatus shown in <figref idref="f0001">FIG. 1</figref> includes an antenna 1, an RF section 2, a CDMA process section 3, a compression/decompression section 4, a voice code process section 5, a speech section 6, an antenna 7, a Bluetooth wireless section (hereinafter referred to as "BT wireless section") 8, a Bluetooth baseband section (hereinafter "BT baseband section") 9, a user interface section 10, a memory section 11, and a control section 12. The speech section 6 includes an amplifier 6a, a speaker 6b, a microphone 6c and an amplifier 6d. The user interface section 10 includes a display section 10a and an input section 10b.

0013A radio signal, which is transmitted from a base station (not shown), is received by the antenna 1 and then input to the RF section 2. The RF section 2 extracts a CDMA signal from the output signal that comes from the antenna 1. The CDMA process section 3 extracts reception data from the CDMA signal that is output from the RF section 2. The compression/decompression section 4 extracts voice data from the reception data that is output from the CDMA process section 3. The voice code process section 5 decodes the voice data that is output from the compression/decompression section 4, thereby reproducing a voice signal. The voice signal is amplified by the amplifier 6a, and the amplified voice signal is output from the speaker 6b as voice.

0014Voice uttered by a user is converted to a voice signal through the microphone 6c. The voice signal is input to the amplifier 6d and amplified to a proper level. The voice code process section 5 encodes the voice signal, which is output from the amplifier 6d, and converts it to voice data. The compression/decompression section 4 compresses the voice data that is output from the voice code process section 5. The CDMA process section 3 generates a CDMA signal including the data output from the compression/decompression section 4. The RF section 2 converts the CDMA signal from the CDMA process section 3 to a radio signal. The radio signal, which is output from the RF section 2, is emitted from the antenna 1 as radio waves.

0015A radio signal, which is transmitted from a communication terminal (not shown) that supports Bluetooth, is received by the antenna 7 and then input to the BT wireless section 8. The BT wireless section 8 extracts a signal according to Bluetooth (hereinafter "BT signal") from the radio signal coming from the antenna 7. The BT baseband section 9 extracts data from the BT signal that is output from the BT wireless section 8. The BT baseband section 9 delivers the extracted data to the control section 12.

0016The BT baseband section 9 has functions for executing Inquiry/Page and Inquiry/Page_Scan, which are stipulated in the Bluetooth standard. The Inquiry/Page is a process that is executed by the master. The Inquiry/Page process executes transmission of an IQ packet, reception of an FHS packet, and transmission/reception of an ID packet. The Inquiry/Page_Scan is a process that is executed by a slave. The Inquiry/Page_Scan process executes reception of the IQ packet, transmission of the FHS packet, and transmission/reception of the ID packet.

0017The display section 10a includes an LCD (liquid crystal display), an LED (light emitting diode), or the like. The display section 10a displays various information that is to be indicated to the user. The input section 10b includes various keys. The input section 10b inputs the user's instruction through depression of the keys.

0018The memory section 11 includes, for instance, a ROM, a DRAM (dynamic RAM), an SRAM (static RAM), or a flash memory, depending on cases. The memory section 11 stores an operational program for the control section 12. The memory section 11 stores various data, for instance, various setting information, various reception data or various data produced in the apparatus. The operation program includes a BT communication control program P. The BT communication control program P causes the control section 12 to execute a process, which will be described later. The BT communication control program P may be stored in the memory section 11 at the stage of manufacture of the wireless communication apparatus, or may be stored in the memory section 11 at a proper stage via a communication network or via a communication cable that is connected to a communication interface (not shown).

0019The control section 12 mainly comprises a microcomputer. The control section 12 realizes operations of the wireless communication apparatus by executing various controls according to software processes based on the operation program stored in the memory section 11.

0020Next, the characteristic operation of the present invention in the wireless communication apparatus with the above structure is described.

0021When the Bluetooth communication function is enabled by the user, the control section 12 executes a Bluetooth control process (hereinafter "BT control process"), as illustrated in <figref idref="f0002">FIG. 2</figref>, on the basis of the BT communication control program.

0022In step Sa1, the control section 12 instructs the BT baseband section 9 to start Inquiry/Page_Scan, and activates an OFF timer. The OFF timer, for example, can be realized by clocking according to another task process by the control section 12. Alternatively, the OFF timer may be realized by using a clock circuit. The OFF timer times out at the end of counting of a predetermined OFF timer value.

0023Upon receiving the instruction from the control section 12, the BT baseband section 9 starts Inquiry/Page_Scan. If a connectable device can be detected by the Inquiry/Page_Scan, the BT baseband section 9 informs the control section 12 of the detection of the connectable device. In this state, the present wireless communication device acts as a slave in the Bluetooth communication.

0024In step Sa2 and step Sa3, the control section 12 determines whether the connectable device is detected, or stands by for time-out of the OFF timer. If the connectable device is detected prior to time-out of the OFF timer, the control section 12 advances from step Sa2 to step Sa4. In step Sa4, the control section 12 executes Bluetooth connection to the detected connectable device. Then, in step Sa5, the control section 12 passes into a standby operation in a power-save mode that is stipulated in the Bluetooth standard.

0025If the OFF timer times out without detection of the connectable device, the control section 12 advances from step Sa3 to step Sa6. In step Sa6, the control section 12 instructs the BT baseband section 9 to halt the Inquiry/Page_Scan function, and activates an ON timer. The ON timer, for example, can be realized by clocking according to another task process by the control section 12. Alternatively, the ON timer may be realized by using a clock circuit. The ON timer times out at the end of counting of a predetermined ON timer value.

0026In step Sa7, the control section 12 stands by for time-out of the ON timer. Thus, the state (hereinafter referred to as "sleep state"), in which the BT baseband section 9 executes neither Inquiry/Page_Scan nor Inquiry/Page, continues after the time-out of the OFF timer until the end of passage of a time period corresponding to the ON timer value.

0027Upon time-out of the ON timer, the control section 12 advances from step Sa7 to step Sa8. In step Sa8, the control section 12 instructs the BT baseband section 9 to start Inquiry/Page, and activates a call timer. The call timer, for example, can be realized by clocking according to another task process by the control section 12. Alternatively, the call timer may be realized by using a clock circuit. The call timer times out at the end of counting of a predetermined call timer value.

0028Upon receiving the instruction from the control section 12, the BT baseband section 9 starts Inquiry/Page. If a connectable device is be detected by the Inquiry/Page, the BT baseband section 9 informs the control section 12 of the detection of the connectable device. In this state, the present wireless communication apparatus acts as the master of the Bluetooth communication.

0029In step Sa9 and step Sa10, the control section 12 determines whether the connectable device is detected, or stands by for time-out of the call timer. If the call timer times out without detection of the connectable device, the control section 12 advances from step Sa10 to step Sa11. In step Sa11, the control section 12 instructs the BT baseband section 9 to halt the Inquiry/Page function, and activates the ON timer. Then, the control section 12 returns to step Sa7 in the standby state. Thus, if the connectable device is not successfully detected by the master operation during the time period corresponding to the call timer value, the control section 12 halts the master operation and returns to the sleep state.

0030On the other hand, if the connectable device is detected prior to time-out of the call timer, the control section 12 advances from step Sa9 to step Sa12. In step Sa12, the control section 12 executes Bluetooth connection to the detected connectable device. In a subsequent step Sa13, the control section 12 issues a request for role switch to the connected device. The role switch is a process for changing the master/slave roles of the connected devices, which is stipulated in the Bluetooth standard.

0031In a step Sa14, the control section 12 confirms whether the request for the role switch is accepted. If the role switch is rejected, the control section 12 advances from step Sa14 to step Sa15. In step Sa15, the control section 12 activates the ON timer. Then, the control section 12 returns to step Sa7 in the standby state. Thus, if the request for the role switch is rejected, the control section 12 halts the master operation and returns to the sleep state. However, if the request for the role switch is accepted, the control section 12 advances from step Sa14 to step Sa16 and passes into a standby operation in a power-save mode.

0032In the wireless communication apparatus according to this embodiment, the OFF timer value and ON timer value can freely be chosen by the user. Thus, the control section 12 executes a user setting process, as illustrated in <figref idref="f0003">FIG. 3</figref>, on the basis of the BT communication control program.

0033The control section 12 starts the process illustrated in <figref idref="f0003">FIG. 3</figref> in response to the user's request for change of settings relating to the Bluetooth communication function. In step Sb1, the control section 12 confirms whether the request for change of setting is directed to a change of the OFF timer value. If the user requests a change of the OFF timer value, the control section 12 advances from step Sb1 to step Sb2. In step Sb2, the control section 12 accepts designation of a value by the user. In a subsequent step Sb3, the control section 12 updates the OFF timer value on the basis of the designated value. Thus, the control section 12 completes the user setting process.

0034On the other hand, if the user's request is not directed to the change of the OFF timer value, the control section 12 advances from step Sb1 to step Sb4. In step Sb4, the control section 12 confirms whether the request for change of setting is directed to a change of the ON timer value. If the user requests a change of the ON timer value, the control section 12 advances from step Sb4 to step Sb5. In step Sb5, the control section 12 accepts designation of a value by the user. In a subsequent step Sb6, the control section 12 updates the ON timer value on the basis of the designated value. Thus, the control section 12 completes the user setting process.

0035If the user's request is not directed to the change of the ON timer value, the control section 12 advances to a process (not shown) for changing other settings.

0036As has been described above, according to the wireless communication apparatus of the present embodiment, if a connectable device is not successfully detected during the time period corresponding to the OFF timer value while the wireless communication apparatus is acting as a slave, the wireless communication apparatus passes into the sleep state in which neither Inquiry/Page_Scan nor Inquiry/Page is executed. It is thus possible to save power consumption, which would be needed if Inquiry/Page_Scan and Inquiry/Page are executed. After the sleep state is continued for the time period corresponding to the ON timer value, the wireless communication apparatus of the present embodiment acts as the master and executes a search for a connectable device by Inquiry/Page. Then, by executing a master/slave role switch with the detected connectable device, the wireless communication apparatus of this embodiment can return to the standby state as the normal slave.

0037According to the present embodiment, the OFF timer value and ON timer value can be updated by the user's designation. The user can freely set the time period up to the transition to the sleep state and the time period for continuation of the sleep state. Hence, the wireless communication apparatus of this embodiment can operate in a flexible manner according to the user's needs.

0038Various modifications can be made to the present embodiment, as will be described below.

0039The present invention is applicable to any communication scheme, other than Bluetooth, if one of a plurality of terminals acts as a master and the other(s) as slave(s).

0040In the present embodiment, the wireless communication apparatus, which supports W-CDMA and Bluetooth, is used by way of example. The present invention, however, is applicable to a wireless communication apparatus that supports PCD (Personal Digital Cellular) instead of W-CDMA, or to a wireless communication apparatus that is dedicated to Bluetooth.

0041The OFF timer value and ON timer value may be fixed. Even in the case where the OFF timer value and ON timer value are made variable, it is possible to prepare a plurality of OFF timer values and a plurality of ON timer values in association with a plurality of modes, and to use the OFF timer value and ON timer value corresponding to the selected mode.