Patent Publication Number: US-2022240188-A1

Title: Control device, wireless communication device, wireless system, and power supply control method

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of Japanese Patent Application No. 2021-009807, filed on Jan. 25, 2021, the entire disclosure of which is incorporated by reference herein. 
     FIELD 
     The present disclosure relates generally to a control device, a wireless communication device, a wireless system, and a power supply control method. 
     BACKGROUND 
     Communication systems include a plurality of communication terminals that are connected across a network. The power supply of each of the communication terminals is controlled remotely to reduce power consumption, carry out maintenance work, and the like of the plurality of communication terminals. For example, sending to each communication terminal connected to a wired Local Area Network (LAN) a wake-up command by using a function called Wake on LAN (WoL) enables to wake up each communication terminal from sleep mode. Likewise, sending to each communication terminal connected to a wireless LAN a wake-up command by using a function called Wake on Wireless LAN (WoWLAN) enables to wake up each communication terminal from sleep mode. Unexamined Japanese Patent Application Publication No. 2005-18377 describes an example of this type of wireless system. 
     In the wireless system described in Unexamined Japanese Patent Application Publication No. 2005-18377, when, in a state in which a main power supply of a system main body of a computer device is not turned ON, receiving means of the computer device receives, from an access point on the network, a frame including a magic packet commanding the power to be turned ON, the main power supply of the system main body is turned ON. 
     SUMMARY 
     A control device according to a first aspect of the present disclosure is 
     a control device that controls a power supply of a wireless communication device connected across a wireless local area network, the control device including: 
     a control-side operation switcher that, in accordance with a power operation or a supply state of power from a power supply source that supplies power to the control device, switches between a control-side access point mode for receiving a connection request from the wireless communication device and a control-side station mode for sending a connection request to the wireless communication device; 
     a control-side power supply controller that, in accordance with the power operation or the supply state of the power from the power supply source, generates a sleep command commanding switching of the wireless communication device to a device-side sleep mode or a wake-up command commanding the wireless communication device to wake up from the sleep mode, and switches between a control-side sleep mode for limiting a supply of power within a range in which detection of the power operation is possible and a control-side wake-up mode; and 
     a control-side communicator that receives a connection request from the wireless communication device in the control-side access point mode and sends a connection request to the wireless communication device in the control-side station mode to establish a connection with the wireless communication device, and sends, to the wireless communication device with which the connection is established, the sleep command or the wake-up command generated by the control-side power supply controller. 
     It is preferable that, when a power OFF of the control device is commanded by the power operation, 
     the control-side power supply controller generates the sleep command, 
     the control-side communicator sends, to the wireless communication device, the sleep command generated by the power supply controller, and 
     after the control-side communicator sends the sleep command, the control-side power supply controller switches to the control-side sleep mode. 
     It is preferable that, when a power ON of the control device is commanded by the power operation, or supplying of power is started from a state in which power is not being supplied from the power supply source, 
     the control-side power supply controller switches to the control-side wake-up mode and generates the wake-up command, 
     the control-side operation switcher switches to the control-side station mode, 
     after the control-side operation switcher switches to the control-side station mode, the control-side communicator sends the connection request to the wireless communication device and, when the connection with the wireless communication device is established, sends the wake-up command to the wireless communication device, and 
     after the control-side communicator sends the wake-up command, the control-side operation switcher switches to the control-side access point mode. 
     A wireless communication device according to a second aspect of the present disclosure is 
     a wireless communication device in which a power supply is controlled by a control device connected across a wireless local area network, the wireless communication device including: 
     a device-side operation switcher that, in accordance with a supply state of power from a power supply source that supplies power to the wireless communication device or a sleep command commanding switching to a device-side sleep mode or a wake-up command commanding waking up from the sleep mode sent from the control device, switches between a device-side access point mode for receiving a connection request from the control device and a device-side station mode for sending a connection request to the control device; 
     a device-side communicator that receives a connection request from the control device in the device-side access point mode and sends a connection request to the control device in the device-side station mode to establish a connection with the control device, and receives, from the control device with which the connection is established, the sleep command or the wake-up command; and 
     a device-side power supply controller that, in accordance with the supply state of the power from the power supply source or the sleep command or the wake-up command, switches between the device-side sleep mode for limiting a supply of power within a range in which receiving of the connection request from the control device is possible and a device-side wake-up mode. 
     It is preferable that, when the device-side communicator receives the sleep command from the control device, the device-side operation switcher switches to the device-side access point mode, and 
     after the device-side operation switcher switches to the device-side access point mode, the device-side power supply controller switches to the device-side sleep mode. 
     It is preferable that, when the device-side communicator receives the wake-up command from the control device, the device-side power supply controller switches to the device-side wake-up mode, and 
     when the device-side power supply controller switches to the device-side wake-up mode, the device-side operation switcher switches to the device-side station mode. 
     It is preferable that, when supplying of power is started from a state in which power is not being supplied from the power supply source, 
     the device-side power supply controller switches to the device-side wake-up mode, 
     the device-side operation switcher switches to the device-side access point mode, and 
     after the device-side operation switcher switches to the device-side access point mode, the device-side power supply controller switches to the device-side sleep mode. 
     A wireless system according to a third aspect of the present disclosure includes: 
     the control device; and 
     at least one of the wireless communication device. 
     A power supply control method according to a fourth aspect of the present disclosure is 
     a power supply control method performed by a wireless system including a wireless communication device and a control device connected over a wireless local area network, the method being for controlling a power supply of the wireless communication device, the method including: 
     in accordance with a power operation of the control device or a supply state of power from a power supply source that supplies power to the control device, sending a sleep command commanding switching to a device-side sleep mode to the wireless communication device from the control device that is operating in a control-side access point mode for receiving a connection request from the wireless communication device; 
     when the wireless communication device operating in a device-side station mode for sending a connection request to the control device receives the sleep command, switching the wireless communication device to a device-side access point mode for receiving a connection request from the control device, and switching the wireless communication device to the device-side sleep mode; 
     in accordance with the power operation of the control device or the supply state of the power from the power supply source, sending a wake-up command commanding wake up from the device-side sleep mode to the wireless communication device from the control device operating in a control-side station mode for sending a connection request to the wireless communication device; and 
     when the wireless communication device operating in the device-side access point mode receives the wake-up command, switching the wireless communication device to the device-side station mode and switching the wireless communication device to the device-side wake-up mode. 
     The control device according to the present disclosure receives a connection request from the wireless communication device in the control-side access point mode and sends a communication request to the wireless communication device in the control-side station mode to establish a connection with the wireless communication device. The control device sends, to the wireless communication device with which the connection is established, a sleep command or a wake-up command to control the power supply of the wireless communication device. This configuration enables, even when the connection with the wireless communication device is cut off, to establish a connection with the wireless communication device and remotely control the power supply control of the wireless communication device. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A more complete understanding of this application can be obtained when the following detailed description is considered in conjunction with the following drawings, in which: 
         FIG. 1  is a block diagram illustrating the configuration of a wireless system according to an embodiment; 
         FIG. 2  is a block diagram illustrating the configuration of a control device according to the embodiment; 
         FIG. 3  is a block diagram illustrating the hardware configuration of the control device according to the embodiment; 
         FIG. 4  is a block diagram illustrating the configuration of a wireless communication device according to the embodiment; 
         FIG. 5  is a block diagram illustrating the hardware configuration of the wireless communication device according to the embodiment; 
         FIG. 6  is a sequence diagram illustrating an example of operations of power supply control carried out by the wireless system according to the embodiment; 
         FIG. 7  is a sequence diagram illustrating an example of operations of the power supply control carried out by the wireless system according to the embodiment; 
         FIG. 8  is a sequence diagram illustrating an example of operations of the power supply control carried out by the wireless system according to the embodiment; 
         FIG. 9  is a block diagram illustrating the configuration of a wireless system according to a modified example of the embodiment; and 
         FIG. 10  is a sequence diagram illustrating an example of operations of the power supply control carried out by the wireless system according to the embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     In the computer device of the wireless system described in Unexamined Japanese Patent Application Publication No. 2005-18377, power is supplied to the receiving means for receiving the frame including the magic packet, even in a state in which the main power supply of the system main body is not turned ON. Power is constantly supplied to the access point of the wireless system. Consequently, the connection that is established between the computer device and the access point after sending of a connection request from the computer device to the access point is maintained. 
     When the supplying of power to the computer device and the access point is stopped, the computer device and the access point stop, and the connection between the computer device and the access point is cut off. Restarting thereafter the supplying of power to the computer device and the access point does not enable sending the frame including the magic packet from the access point to the computer device, since the connection between the computer device and the access point is not established. Consequently, the main power supply of the system main body of the computer device cannot be turned ON remotely. This problem is not limited to computer devices that connect to access points, and may occur in various types of wireless communication devices that have power supplies that are controlled by control devices connected across wireless LANs. 
     The present disclosure is made with the view of the above situation, and an objective of the present disclosure is to provide a control device, a wireless communication device, a wireless system, and a power supply control method whereby, when a connection with a wireless communication device is cut off, the connection with the wireless communication device is reestablished, thereby enabling remote power supply control of the wireless communication device. 
     Hereinafter, a control device, a wireless communication device, a wireless system, and a power supply control method according to various embodiments are described in detail while referencing the drawings. Note that, in the drawings, identical or equivalent components are denoted with the same reference numerals. 
     A wireless system  1  illustrated in  FIG. 1  includes a control device  10  and a wireless communication device  20 . The control device  10  and the wireless communication device  20  are connected across a wireless Local Area Network (LAN)  30 . Specifically, the wireless communication device  20  sends a connection request to the control device  10  to establish a connection between the control device  10  and the wireless communication device  20 . In this embodiment, an example of the wireless system  1  is described in which the wireless system  1  is installed on a marine vessel, and the control device  10  is a Very High Frequency (VHF) radio station. 
     The control device  10  is provided in the wheelhouse, and the wireless communication device  20  is provided at a position separated from the control device  10  such as, for example, at the stern. Input/output devices such as, for example, a speaker  41  and a microphone  42  are connected to the control device  10 . The microphone  42  is provided with operators such as a Push To Talk (PTT) switch that is pressed when transmitting, a switch for remote controlling the control device  10 , and the like. External devices such as, for example, a Global Positioning System (GPS) antenna  43 , and input/output devices such as, for example, a horn speaker  44  are connected to the wireless communication device  20 . 
     In one example, the control device  10  extracts data from a VHF signal received from a VHF radio station installed on another marine vessel, and sends the extracted data to the speaker  41  and the wireless communication device  20 . The speaker  41  outputs speech included in the data acquired from the control device  10 . The wireless communication device  20  sends the data acquired from the control device  10  to the horn speaker  44 . The horn speaker  44  outputs speech included in the data acquired from the wireless communication device  20 . 
     Additionally, in one example, the control device  10  generates a VHF signal based on speech data acquired from the microphone  42 , and sends the generated VHF signal to the VHF radio station installed on the other marine vessel. The control device  10  acquires, from the wireless communication device  20 , data such as, for example, position information that the wireless communication device  20  acquires from the GPS antenna  43 , and displays the position of the marine vessel on a display screen. 
     In addition to the sending and receiving of the speech and data described above, the control device  10  carries out power supply control of the wireless communication device  20  in accordance with a power operation of the control device  10  or a supply state of power from the power supply source. Specifically, in accordance with a power operation or the supply state of power from the power supply source, the control device  10  generates a sleep command commanding switching to a device-side sleep mode or a wake-up command commanding wake up from the device-side sleep mode, and sends the generated sleep command or wake-up command to the wireless communication device  20  to carry out the power supply control of the wireless communication device  20 . 
     Next, the various components of the control device  10  are described in detail. As illustrated in  FIG. 2 , the control device  10  includes a control-side operation switcher  11  that switches between a control-side access point mode and a control-side station mode, a control-side communicator  12  that carries out communication with the wireless communication device  20 , and a control-side power supply controller  13  that carries out the generation of the sleep command and the wake-up command and the switching between the control-side sleep mode and the control-side wake-up mode. In order to send and receive the VHF signal, the control device  10  includes a VHF antenna  14  that sends and receives the VHF signal, and a VHF communicator  15  that generates the VHF signal from sending data and extracts data from the VHF signals. Furthermore, the control device  10  includes an input/output device  16  that outputs the data extracted by the VHF communicator  15  and inputs/receives the sending data. 
     The control-side operation switcher  11  switches between the control-side access point mode and the control-side station mode in accordance with a power operation of the control device  10  or the supply state of power from the power supply source. The power operation of the control device  10  includes not only an operation of a power switch provided on a main body of the control device  10 , but also includes automatic power operations set in advance in the control device  10  such as, for example, automatically powering OFF when the control device  10  has not been operated for a certain amount of time. In one example, the power supply source is a power supply system installed on a marine vessel. The control-side access point mode is a mode in which the control device  10  receives a connection request from the wireless communication device  20 . The control-side station mode is a mode in which the control device  10  sends a connection request to the wireless communication device  20 . 
     Specifically, when power ON of the control device  10  is commanded by the power operation, the control-side operation switcher  11  switches to the control-side station mode. In this case, when the mode immediately previous is the control-side station mode, switching to the control-side station mode means maintaining the control-side station mode. After sending of a wake-up command to the wireless communication device  20  in the control-side station mode, the control-side operation switcher  11  switches from the control-side station mode to the control-side access point mode. 
     When operating in the control-side access point mode, the control-side communicator  12  receives the connection request from the wireless communication device  20 . Specifically, when a probe request that is a connection request from the wireless communication device  20  is received, the control-side communicator  12  sends a probe response that is a connection response. The probe response includes information for establishing a connection between the control device  10  and the wireless communication device  20  such as, for example, a Service Set ID (SSID). The control device  10  and the wireless communication device  20  hold, in advance, information about the Media Access Control (MAC) address of each other. 
     Thereafter, when the control-side communicator  12  receives an authentication request from the wireless communication device  20 , the control-side communicator  12  sends an authentication response. Specifically, the control-side communicator  12  carries out 4-way handshake authentication procedures with the wireless communication device  20 . After the authentication procedures are completed, when the control-side communicator  12  receives an Internet Protocol (IP) address request from the wireless communication device  20 , the control-side communicator  12  sends an IP address response. As a result, an IP address is allocated to the wireless communication device  20 , and a connection between the control device  10  and the wireless communication device  20  is established. 
     When operating in the control-side station mode, the control-side communicator  12  sends a connection request to the wireless communication device  20 . Specifically, the control-side communicator  12  sends a probe request that is a connection request to the wireless communication device  20 . Then, when the control-side communicator  12  receives a probe response that is a connection response from the wireless communication device  20 , the control-side communicator  12  starts authentication procedures. Specifically, the control-side communicator  12  sends an authentication request to the wireless communication device  20 . Then, when the control-side communicator  12  receives an authentication response from the wireless communication device  20 , the control-side communicator  12  sends an IP address request. When the control-side communicator  12  receives an IP address response from the wireless communication device  20 , an IP address is allocated to the control device  10 , and a connection between the control device  10  and the wireless communication device  20  is established. 
     As described above, when the connection between the control device  10  and the wireless communication device  20  is established, sending and receiving of the sleep command, the wake-up command, the speech data, data not including speech such as, for example, position information, and the like between the control device  10  and the wireless communication device  20  is enabled. For example, the control-side communicator  12  generates a LAN frame that includes, in data fields, the sleep command, the wake-up command, the speech data, the data not including speech, or the like, and that conforms to the standard of the wireless LAN  30 , and sends the LAN frame to the wireless communication device  20 . 
     The sleep command includes the MAC address of the target device, that is, the wireless communication device  20 , and commands switching of the wireless communication device  20  to the device-side sleep mode. As with a magic packet used in Wake on LAN (WoL), the wake-up command includes, for example, a data pattern consisting of 16 repetitions of the MAC address of the target device, that is, the wireless communication device  20 . The wake-up command commands switching of the wireless communication device  20  to the device-side wake-up mode. 
     Additionally, in one example, the control-side communicator  12  receives the LAN frame sent from the wireless communication device  20 . When the control-side communicator  12  acquires the LAN frame from the wireless communication device  20 , the control-side communicator  12  extracts the speech data, the data not including speech, and the like included in the data fields. Then, the control-side communicator  12  sends, from among the extracted data and to the VHF communicator  15 , data used in VHF communication such as the speech data, for example. 
     In accordance with the power operation or the supply state of power from the power supply source, the control-side power supply controller  13  carries out the generation of the sleep command or the wake-up command, and the switching between the control-side sleep mode and the control-side wake-up mode. The control-side sleep mode is a mode in which the supplying of power to the various components of the control device  10  is limited within a range in which the detection of power operations is possible. The control-side wake-up mode is a mode in which power is supplied to the various components of the control device  10 . When power OFF of the control device  10  is commanded by a power operation, the control-side power supply controller  13  generates a sleep command and sends the generated sleep command to the control-side communicator  12 . The control-side communicator  12  sends the sleep command to the wireless communication device  20  and, then, the control-side power supply controller  13  switches to the control-side sleep mode. 
     When power ON of the control device  10  is commanded by a power operation, the control-side power supply controller  13  generates a wake-up command and sends the generated wake-up command to the control-side communicator  12 . Then, the control-side power supply controller  13  switches to the control-side wake-up mode. 
     The VHF communicator  15  carries out signal processing such as frequency conversion, amplification, filtering, demodulation, and the like of the VHF signal received by the VHF antenna  14  to extract the data from the VHF signal. The VHF communicator  15  sends the extracted data to the control-side communicator  12  and the input/output device  16 . The VHF communicator  15  carries out signal processing such as modulation, filtering, amplification, frequency conversion, and the like of the sending data acquired from the control-side communicator  12  or the input/output device  16  to generate a VHF signal, and sends the VHF signal via the VHF antenna  14 . 
     The input/output device  16  sends the data acquired from the VHF communicator  15  to the speaker  41 . The speaker  41  plays back the speech included in the data acquired from the input/output device  16 . The input/output device  16  sends the data acquired from the microphone  42  to the VHF communicator  15 . 
     An example of a hardware configuration for realizing the control device  10  illustrated in  FIG. 2  is described using  FIG. 3 . The hardware configuration of the control device  10  includes a Central Processing Unit (CPU)  61 , a memory  62 , a power supply control circuit  63 , a LAN communication Interface (IF)  64 , a VHF communication IF  65 , and an input/output IF  66 . The CPU  61 , the memory  62 , the power supply control circuit  63 , the LAN communication IF  64 , the VHF communication IF  65 , and the input/output IF  66  are connected to each other via a bus  60 . 
     The CPU  61  executes a program stored in the memory  62  to realize the functions of the various components of control device  10 . The power supply control circuit  63  is a circuit for realizing the functions of the control-side power supply controller  13 , is supplied with power from the power supply source, and controls the supply of power to the various components of the control device  10 . The LAN communication IF  64  is an interface that is connected to the wireless LAN  30  and is for enabling communication with the wireless communication device  20 . The VHF communication IF  65  is an interface for enabling communication with other VHF radio stations. The control device  10  is connected to the speaker  41  and the microphone  42  via the input/output IF  66 . 
     In the example of  FIG. 3 , the control device  10  includes one each of the CPU  61  and the memory  62 , but a configuration is possible in which the control device  10  includes a plurality of the CPU  61  and a plurality of the memory  62 . In such a case, the plurality of the CPU  61  and the plurality of the memory  62  may work together to realize the functions of the various components of the control device  10 . In order to reduce power consumption, a configuration is possible in which the power supply control circuit  63  supplies power to only a portion of the plurality of the CPU  61  and supplies power to only a portion of the plurality of the memory  62 . 
     Next, details of the various components of the wireless communication device  20  that connects via the wireless LAN  30  to the control device  10  are described. As illustrated in  FIG. 4 , the wireless communication device  20  includes a device-side operation switcher  21  that switches between a device-side access point mode and a device-side station mode, a device-side communicator  22  that carries out communication with the control device  10 , and a device-side power supply controller  23  that carries out switching between a device-side sleep mode and a device-side wake-up mode. Furthermore, the wireless communication device  20  includes an input/output device  24  that outputs data acquired by the device-side communicator  22 , receives input of the sending data, acquires position information, and the like. 
     The device-side operation switcher  21  switches between the device-side access point mode and the device-side station mode in accordance with the supply state of power from the power supply source or a sleep command or a wake-up command sent from the control device  10 . In one example, the power supply source is a power supply system installed on a marine vessel and is shared with the control device  10 . The device-side access point mode is a mode in which the wireless communication device  20  receives a connection request from the control device  10 . The device-side station mode is a mode in which the wireless communication device  20  sends a connection request to the control device  10 . 
     Specifically, when a sleep command is sent from the control device  10  or when supplying of power is started from a state in which power is not being supplied from the power supply source, the device-side operation switcher  21  switches to the device-side access point mode. In such a case, when the mode immediately previous is the device-side access point mode, switching to the device-side access point mode means maintaining the device-side access point mode. When a wake-up command is sent from the control device  10 , the device-side operation switcher  21  switches from the device-side access point mode to the device-side station mode. 
     When operating in the device-side access point mode, the device-side communicator  22  receives the connection request from the control device  10 . Specifically, when the device-side communicator  22  receives a probe request that is a connection request from the control-side communicator  12  of the control device  10 , the device-side communicator  22  sends a probe response that is a connection response. Then, when the device-side communicator  22  receives an authentication request from the control-side communicator  12 , the device-side communicator  22  sends an authentication response. Specifically, the device-side communicator  22  carries out 4-way handshake authentication procedures with the control-side communicator  12 . After the authentication procedures are completed, when the device-side communicator  22  receives an IP address request from the control-side communicator  12 , the device-side communicator  22  sends an IP address response to the control-side communicator  12 . As a result, an IP address is allocated to the control device  10 , and a connection between the control device  10  and the wireless communication device  20  is established. 
     When operating in the device-side station mode, the device-side communicator  22  sends a connection request to the control-side communicator  12  of the control device  10 . Specifically, the device-side communicator  22  sends a probe request that is a connection request to the control-side communicator  12 . Then, when the device-side communicator  22  receives a probe response that is a connection response from the control-side communicator  12 , the device-side communicator  22  starts authentication procedures. Specifically, the device-side communicator  22  sends an authentication request to the control-side communicator  12 . Then, when the device-side communicator  22  receives an authentication response from the control-side communicator  12 , the device-side communicator  22  sends an IP address request. When the device-side communicator  22  receives an IP address response from the control-side communicator  12 , an IP address is allocated to the wireless communication device  20 , and a connection between the control device  10  and the wireless communication device  20  is established. 
     As described above, when the connection is established between the control device  10  and the wireless communication device  20 , sending and receiving of the sleep command, the wake-up command, the speech data, the data not including speech such as, for example, position information, and the like between the control device  10  and the wireless communication device  20  is enabled. In one example, the device-side communicator  22  generates a LAN frame that includes, in data fields, the speech data, the data not including speech, and the like, and that conforms to the standard of the wireless LAN  30 , and sends the LAN frame to the control device  10 . 
     Additionally, in one example, the device-side communicator  22  receives the LAN frame sent from the control device  10 . When the device-side communicator  22  receives the LAN frame from the control device  10 , the device-side communicator  22  extracts the sleep command, the wake-up command, the speech data, the data not including speech data, or the like included in the data fields. Then, the device-side communicator  22  sends the extracted sleep command or wake-up command to the device-side operation switcher  21  and the device-side power supply controller  23 . The device-side communicator  22  sends the extracted speech data and data not including speech to the input/output device  24 . 
     The device-side power supply controller  23  switches between the device-side sleep mode and the device-side wake-up mode in accordance with the supply state of power from the power supply source or the sleep command or the wake-up command sent from the control device  10 . The device-side sleep mode is a mode in which the supply of power to the various components of the wireless communication device  20  is limited within a range in which connection requests from the control device  10  are receivable. The device-side wake-up mode is a mode in which power is supplied to the various components of the wireless communication device  20 . When the device-side power supply controller  23  receives a sleep command from the device-side communicator  22  or when the supplying of power is started from a state in which power is not being supplied from the power supply source, the device-side power supply controller  23  switches to the device-side sleep mode. 
     When the device-side power supply controller  23  receives a wake-up command from the device-side communicator  22 , the device-side power supply controller  23  switches to the device-side wake-up mode. 
     The input/output device  24  sends the position information acquired from the GPS antenna  43  to the device-side communicator  22 . The input/output device  24  sends the data acquired from the device-side communicator  22  to the horn speaker  44 . The horn speaker  44  plays back the speech included in the data acquired from the input/output device  24 . 
     Next, an example of a hardware configuration for realizing the wireless communication device  20  illustrated in  FIG. 4  is described using  FIG. 5 . The hardware configuration of the wireless communication device  20  includes a CPU  71 , a memory  72 , a power supply control circuit  73 , a LAN communication IF  74 , and an input/output IF  75 . The CPU  71 , the memory  72 , the power supply control circuit  73 , the LAN communication IF  74 , and the input/output IF  75  are connected to each other via a bus  70 . 
     The CPU  71  executes a program stored in the memory  72  to realize the functions of the various components of wireless communication device  20 . The power supply control circuit  73  is a circuit for realizing the functions of the device-side power supply controller  23 , is supplied with power from the power supply source, and controls the supply of power to the various components of the wireless communication device  20 . The LAN communication IF  74  is an interface that connects to the wireless LAN  30  and is for enabling communication with the control device  10 . The wireless communication device  20  is connected to the GPS antenna  43  and the horn speaker  44  via the input/output IF  75 . 
     In the example of  FIG. 5 , the wireless communication device  20  includes one each of the CPU  71  and the memory  72 , but a configuration is possible in which the wireless communication device  20  includes a plurality of the CPU  71  and a plurality of the memory  72 . In such a case, the plurality of the CPU  71  and the plurality of the memory  72  may work together to realize the functions of the various components of the wireless communication device  20 . In order to reduce power consumption, a configuration is possible in which the power supply control circuit  73  supplies power to only a portion of the plurality of the CPU  71  and supplies power to only a portion of the plurality of the memory  72 . 
     Next, a power supply control method carried out by the wireless system  1  that includes the control device  10  and the wireless communication device  20  is described. 
     A description is given, using  FIG. 6 , of control for remotely setting the wireless communication device  20  to the sleep state, specifically control for switching the wireless communication device  20  to the device-side sleep mode, when power OFF is commanded by a power operation of the control device  10 . Prior to the power OFF of the control device  10  being commanded, there is a connection established between the control device  10  that is an access point and the wireless communication device  20  that is a station, and communication is being carried out between the control device  10  and the wireless communication device  20 . 
     When the control-side power supply controller  13  of the control device  10  detects the power operation commanding the power OFF of the control device  10  (sequence Sq 11 ), the control-side power supply controller  13  generates a sleep command (sequence Sq 12 ). The control-side power supply controller  13  sends the generated sleep command to the control-side communicator  12 . The control-side communicator  12  sends the sleep command generated in sequence Sq 12  to the wireless communication device  20  (sequence Sq 13 ). Specifically, the control-side communicator  12  generates a LAN frame including the sleep command in a data field, and sends the generated LAN frame to the wireless communication device  20 . 
     When the processing of sequence Sq 13  ends, the control-side power supply controller  13  switches to the control-side sleep mode (sequence Sq 14 ). In the control-side sleep mode, the control-side power supply controller  13  supplies only the power needed to detect power operations, and does not supply power to the components of the control device  10  that are not used to detect power operations. For example, the power supply control circuit  63  supplies power only to the CPU  61  and the memory  62 , and does not supply power to the LAN communication IF  64 , the VHF communication IF  65 , and the input/output IF  66 . As a result, the power consumption of the control device  10  can be reduced. 
     The device-side communicator  22  of the wireless communication device  20  acquires the sleep command sent in sequence Sq 13  (sequence Sq 21 ). Specifically, the device-side communicator  22  receives the LAN frame sent from the control device  10 , and extracts the sleep command included in the data field of the LAN frame. The device-side communicator  22  sends the extracted sleep command to the device-side operation switcher  21  and the device-side power supply controller  23 . 
     The device-side operation switcher  21  switches to the device-side access point mode in accordance with the sleep command acquired in sequence Sq 21  (sequence Sq 22 ). By switching to the device-side access point mode, the device-side communicator  22  waits for a connection request from the control device  10 . 
     When the processing of sequence Sq 22  ends, the device-side power supply controller  23  switches to the device-side sleep mode (sequence Sq 23 ). In the device-side sleep mode, the device-side power supply controller  23  supplies only power needed for the device-side communicator  22  in the device-side access point mode to wait for connection requests from the control device  10 , and does not supply power to the components of the wireless communication device  20  that are not used to receive connection requests. For example, when a wireless LAN module included in the LAN communication IF  74  is capable of waiting for connection requests from the control device  10  alone, the power supply control circuit  73  supplies power only to the LAN communication IF  74  and the CPU  71 , and does not supply power to the memory  72  and the input/output IF  75 . In this case, it is preferable that the CPU  71  is in a sleep state. As a result, the power consumption of the wireless communication device  20  can be reduced. 
     As described above, the control device  10  switches to the control-side sleep mode and the wireless communication device  20  switches to the device-side sleep mode and, as a result, the power consumption of the wireless system  1  can be reduced. When the control device  10  is in the control-side sleep mode and the wireless communication device  20  is in the device-side sleep mode, the connection between the control device  10  and the wireless communication device  20  is cut off. 
     Next, a case is described, using  FIG. 7 , of control for remotely waking up the wireless communication device  20  when power ON of the control device  10  is commanded by a power operation in a state in which the control device  10  is in the control-side sleep mode and the wireless communication device  20  is in the device-side sleep mode. The control device  10  is waiting for a power operation in the control-side sleep mode, and the wireless communication device  20  is waiting for a connection request from the control device  10  in the device-side sleep mode. 
     When the control-side power supply controller  13  of the control device  10  detects a power operation commanding power ON of the control device  10  (sequence Sq 31 ), the control-side power supply controller  13  switches from the control-side sleep mode to the control-side wake-up mode (sequence Sq 32 ). Specifically, the control-side power supply controller  13  starts supplying power to the various components of the control device  10 . Then, the control-side power supply controller  13  generates a wake-up command (sequence Sq 33 ). The control-side power supply controller  13  sends the generated wake-up command to the control-side communicator  12 . 
     When the processing of sequence Sq 33  ends, the control-side operation switcher  11  switches from the control-side access point mode to the control-side station mode (sequence Sq 34 ). When the processing of sequence Sq 34  ends, the control-side communicator  12  sends a connection request to the wireless communication device  20  (sequence Sq 35 ). 
     The device-side communicator  22  of the wireless communication device  20  operates in the device-side access point mode as described above and waits for the connection request from the control device  10 . When the device-side communicator  22  receives the connection request sent in sequence Sq 35 , the device-side communicator  22  sends a connection response (sequence Sq 51 ). 
     When the control-side communicator  12  receives the connection response sent in sequence Sq 51 , the control-side communicator  12  sends an authentication request to the wireless communication device  20  (sequence Sq 36 ). When the device-side communicator  22  receives the authentication request sent in sequence Sq 36 , the device-side communicator  22  sends an authentication response (sequence Sq 52 ). Specifically, the control-side communicator  12  and the device-side communicator  22  carry out 4-way handshake authentication procedures. 
     When the control-side communicator  12  receives the authentication response sent in sequence Sq 52 , the control-side communicator  12  sends an IP address request (sequence Sq 37 ). When the device-side communicator  22  receives the IP address sent in sequence Sq 37 , the device-side communicator  22  sends an IP address response (sequence Sq 53 ). 
     When the control-side communicator  12  receives the IP address response sent in sequence Sq 53 , a connection between the control device  10  that is a station and the wireless communication device  20  that is an access point is established. Then, the control-side communicator  12  sends the wake-up command generated in sequence Sq 33  to the wireless communication device  20  (sequence Sq 38 ). When the processing of sequence Sq 38  ends, the control-side operation switcher  11  switches from the control-side station mode to the control-side access point mode (sequence Sq 39 ). 
     When the device-side communicator  22  receives the wake-up command sent in sequence Sq 38 , the device-side communicator  22  sends the wake-up command to the device-side power supply controller  23 . When the device-side power supply controller  23  acquires the wake-up command, the device-side power supply controller  23  switches to the device-side wake-up mode (sequence Sq 54 ). Specifically, the device-side power supply controller  23  supplies power to the various components of the wireless communication device  20 . When the processing of sequence Sq 54  ends, the device-side operation switcher  21  switches from the device-side access point mode to the device-side station mode (sequence Sq 55 ). 
     Due to the control-side operation switcher  11  switching to the control-side access point mode and the device-side operation switcher  21  switching to the device-side station mode, the connection between the control device  10  that is a station and the wireless communication device  20  that is an access point is cut off and, as such, reestablishing the connection between the control device  10  and the wireless communication device  20  is needed. As such, when the processing of sequence Sq 55  ends, the device-side communicator  22  sends a connection request to the control device  10  (sequence Sq 56 ). 
     Since the control-side communicator  12  is switched to the control-side access point mode in sequence Sq 39 , the control-side communicator  12  is waiting for a connection request from the wireless communication device  20 . When the control-side communicator  12  receives the connection request sent in sequence Sq 56 , the control-side communicator  12  sends a connection response (sequence Sq 40 ). 
     When the device-side communicator  22  receives the connection response sent in sequence Sq 40 , the device-side communicator  22  sends an authentication request to the control device  10  (sequence Sq 57 ). When the control-side communicator  12  receives the authentication request sent in sequence Sq 57 , the control-side communicator  12  sends an authentication response (sequence Sq 41 ). Specifically, the control-side communicator  12  and the device-side communicator  22  carry out 4-way handshake authentication procedures. 
     When the device-side communicator  22  receives the authentication response sent in sequence Sq 41 , the device-side communicator  22  sends an IP address request (sequence Sq 58 ). When the control-side communicator  12  receives the IP address request sent in sequence Sq 58 , the control-side communicator  12  sends an IP address response (sequence Sq 42 ). When the device-side communicator  22  receives the IP address response sent in sequence Sq 42 , a connection between the control device  10  that is an access point and the wireless communication device  20  that is a station is established. 
     Even when a connection between the control device  10  and the wireless communication device  20  is not established such as in the state in which the control device  10  is in the control-side sleep mode and the wireless communication device  20  is in the device-side sleep mode, as described above, the connection between the control device  10  and the wireless communication device  20  is reestablished as a result of a connection request being sent from the control device  10  to the wireless communication device  20 . Moreover, it is possible to wake up the wireless communication device  20  by sending a wake-up command from the control device  10  to the wireless communication device  20 . 
     When a breaker, a switch or the like provided between the wireless system  1  and the power supply source is open due to the detection of overvoltage, for example, power is no longer supplied to the wireless system  1 . When the supply of power to the wireless system  1  is cut off, the connection between the control device  10  and the wireless communication device  20  is cut off. Next, a description is given, using  FIG. 8 , of control for remotely powering ON the wireless communication device  20  after restarting the supply of power. 
     When the control-side power supply controller  13  of the control device  10  detects that the supplying of power is started from a state in which power is not being supplied from the power supply source (sequence Sq 61 ), the control-side power supply controller  13  switches to the control-side sleep mode (sequence Sq 62 ). The control-side power supply controller  13  can detect the presence/absence of the supply of power on the basis of the potential of the input terminal, for example. As an example, when the potential of the input terminal is higher than a reference value that is a value considered as indicating that power is being supplied, the control-side power supply controller  13  considers that power is being supplied. 
     When the device-side power supply controller  23  of the wireless communication device  20  detects that the supplying of power is started from a state in which power is not being supplied from the power supply source (sequence Sq 71 ), the device-side power supply controller  23  switches to the device-side wake-up mode (sequence Sq 72 ). Then, the device-side power supply controller  23  notifies the device-side operation switcher  21  that the supplying of power has started. The device-side operation switcher  21  receives the notification and switches to the device-side access point mode (sequence Sq 73 ). In such a case, when the mode immediately previous is the device-side access point mode, switching to the device-side access point mode means maintaining the device-side access point mode. When the processing of sequence Sq 73  ends, the device-side power supply controller  23  switches to the device-side sleep mode (sequence Sq 74 ). Then, when a power ON command is input by a power operation of the control device  10 , it becomes possible to remotely wake up the wireless communication device  20 , as illustrated in  FIG. 7 . 
     As described above, the control device  10  of the wireless system  1  according to this embodiment switches between the control-side access point mode and the control-side station mode. After the connection with the wireless communication device  20  is cut off, the control device  10  operates in the control-side station mode, and sends a connection request to the wireless communication device  20  to establish a connection with the wireless communication device  20 . After the connection is established, the control device  10  can send a wake-up command to the wireless communication device  20  to wake up the wireless communication device  20 . When the control device  10  is operating in the control-side access point mode, the control device  10  receives a connection request from the wireless communication device  20  to establish a connection with the wireless communication device  20 . After the connection is established, the control device  10  can send a sleep command to the wireless communication device  20  to switch the wireless communication device  20  to the device-side sleep mode. 
     Even when the connection between the control device  10  and the wireless communication device  20  is cut off, the connection between the control device  10  and the wireless communication device  20  can be reestablished due to the connection request being sent from the control device  10  to the wireless communication device  20  as described above. As a result, remote power supply control of the wireless communication device  20  is possible. 
     In the control-side sleep mode, power is supplied only to the components of the control device  10  needed to detect power operations and, in the device-side sleep mode, power is supplied only to the components of the wireless communication device  20  needed to wait for connection requests. As such, the power consumption of the wireless system  1  can be reduced. 
     The present disclosure is not limited to the embodiment described above. The hardware configurations and flowcharts described above are examples and can be changed or modified as desired. 
     As illustrated in  FIG. 9 , a configuration is possible in which the wireless system  1  includes a plurality of wireless communication devices  20   a ,  20   b . The configurations and operations of the wireless communication devices  20   a ,  20   b  are the same as the wireless communication device  20 . In this case, the control device  10  operating in the control-side access point mode may receive a connection request from each of the wireless communication devices  20   a ,  20   b  to establish a connection with each of the wireless communication devices  20   a ,  20   b . When power OFF of the control device  10  is commanded by a power operation of the control device  10 , the control-side communicator  12  may send a sleep command to each of the wireless communication devices  20   a ,  20   b . After the sleep command has been sent to each of the wireless communication devices  20   a ,  20   b , the control-side power supply controller  13  switches to the control-side sleep mode. 
     The control device  10  operating in the control-side station mode may send a connection request to each of the wireless communication devices  20   a ,  20   b  in order. Specifically, when power ON of the control device  10  is commanded by a power operation of the control device  10 , the control-side communicator  12  first sends a connection request to the wireless communication device  20   a  and establish a connection with the wireless communication device  20   a  as described above. Then, the control-side communicator  12  sends a wake-up command to the wireless communication device  20   a . When the control-side communicator  12  sends the wake-up command to the wireless communication device  20   a , the connection with the wireless communication device  20   a  is cut off, and the control-side communicator  12  sends a connection request to the wireless communication device  20   b  to establish a connection with the wireless communication device  20   b . Then, the control-side communicator  12  sends a wake-up command to the wireless communication device  20   b . After sending a wake-up command to each of the wireless communication devices  20   a ,  20   b , the control-side operation switcher  11  switches to the control-side access point mode. 
     Devices that are connectible to the control device  10  are not limited to the wireless communication devices  20 ,  20   a , and  20   b . As illustrated in  FIG. 9 , a configuration is possible in which a mobile terminal  40  connects to the control device  10  via the wireless LAN  30 . In one example, the mobile terminal  40  is implemented as a smartphone, and can carry out remote operation of the control device  10 , and can provide information such as atmospheric pressure, environment light, and the like to the control device  10 . 
     The control for remotely powering ON the wireless communication device  20  after restarting the supply of power is not limited to the example described above. A configuration is possible in which the control device  10  is woken up automatically as illustrated in  FIG. 10  when the supplying of power is started from a state in which power is not being supplied from the power supply source. Sequence Sq 61  of  FIG. 10  is the same as the processing of sequence Sq 61  of  FIG. 8 . When the control-side power supply controller  13  of the control device  10  detects that the supplying of power is started from a state in which power is not being supplied from the power supply source (sequence Sq 61 ), the control device  10  carries out the processing from sequence Sq 32  illustrated in  FIG. 7 . The processing of sequences Sq 71  to Sq 74  carried out by the wireless communication device  20  are the same as sequences Sq 71  to Sq 74  illustrated in  FIG. 8 . Then, when the connection request from the control device  10  is received, the processing from sequence Sq 51  is carried out in the same manner as in  FIG. 7 . As a result, after the restarting of the supply of power, the control device  10  can be automatically woken up and the wireless communication device  20  can be remotely woken up. 
     The conditions for switching between the control-side access point mode and the control-side station mode are not limited to the examples described above. For example, a configuration is possible in which a notifications are sent at a set interval between the control device  10  and the wireless communication device  20  while there is a connection established between the control device  10  and the wireless communication device  20  and, if a notification is not obtained, the control device  10  switches to the control-side station mode and the wireless communication device  20  switches to the device-side access point mode. As a result, the connection between the control device  10  and the wireless communication device  20  can be reestablished. 
     The method for establishing a connection between the control device  10  and the wireless communication device  20  is not limited to the example described above, and any method may be used. In the embodiment described above, the control device  10  that is operating in the control-side access point mode waits for a connection request from the wireless communication device  20  without sending a beacon. However, a configuration is possible in which the control device  10  sends a beacon at a set interval. This also applies to the wireless communication device  20  that is operating in the device-side access point mode. 
     The control device  10  is not limited to a VHF radio station and may be a radio station that carries out communication on a desired frequency, or may be any other communication device that carries out wireless LAN communication. The input/output device connected to the control device  10  is not limited to the example described above, and any input/output device may be used. A configuration is possible in which the input/output device  16  of the control device  10  acquires speech data from a microphone installed in the control device  10 , and/or speech is output from a speaker installed in the control device  10 . 
     The external device connected to the wireless communication device  20  is not limited to the example described above, and any external device may be used. A configuration is possible in which the device-side operation switcher  21  switches between the device-side access point mode and the device-side station mode in accordance with a power operation of the wireless communication device  20 . The power operation of the wireless communication device  20  includes not only an operation of a power switch provided on a main body of the wireless communication device  20 , but also includes automatic power operations set in advance in the wireless communication device  20  such as, for example, automatically powering OFF when a state in which data cannot be acquired from the control device  10 , for example, continues for a certain amount of time or longer. 
     The operations of the wireless communication device  20  when power OFF is commanded by a power operation of the wireless communication device  20  are the same as the operations when a sleep command is received from the control device  10 . The operations of the wireless communication device  20  when power ON is commanded by a power operation of the wireless communication device  20  are the same as the operations when a wake-up command is received from the control device  10 . 
     A configuration is possible in which the control device  10  and the wireless communication device  20  are each supplied with power from an independent power supply source. 
     The wireless system  1  is not limited to being installed on a marine vessel and may be installed on any vehicle. The wireless system  1  is not limited to a wireless system of a vehicle, and may be any wireless system. 
     The foregoing describes some example embodiments for explanatory purposes. Although the foregoing discussion has presented specific embodiments, persons skilled in the art will recognize that changes may be made in form and detail without departing from the broader spirit and scope of the invention. Accordingly, the specification and drawings are to be regarded in an illustrative rather than a restrictive sense. This detailed description, therefore, is not to be taken in a limiting sense, and the scope of the invention is defined only by the included claims, along with the full range of equivalents to which such claims are entitled.