JP2013055426A - Communication device, control method of communication device, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such a problem that it is impossible to continue data transmission reception processing when an access point disappears while terminals performs the data transmission reception processing via the access point.SOLUTION: A communication device which connects and communicates with a base station, comprises: an acquisition unit for acquiring an apparatus identifier of a communication partner device; a detection unit for detecting disappearance of a base station; a detection unit for detecting the communication partner device with which the communication device had communicated before the disappearance of the base station, by using the apparatus identifier acquired by the acquisition unit, when the disappearance of the base station is detected; and a resumption unit for performing processing to resume communication between the communication device and the communication partner device by making one of the communication device and the communication partner device as a new base station, when the detection unit detects the communication partner device.

Description

  The present invention relates to a communication device, a communication device control method, and a program.

  In recent years, wireless communication typified by wireless LAN compliant with the IEEE 802.11 standard series has attracted attention, and various compatible devices have been developed and sold. In the case of communication using a wireless LAN, a device called an access point (hereinafter also referred to as “AP”) serves as a base station to form a wireless network and control the wireless network. Terminals participating in the wireless network must share wireless parameters that are network components of the base station. The terminal can participate in the wireless network by sharing this wireless parameter with the base station. The base station broadcasts a synchronization signal called a beacon in the network, and the terminal receives the beacon, thereby realizing wireless communication in synchronization with the base station. That is, the base station is indispensable for the wireless network. Therefore, when the base station disappears from the wireless network, the wireless network automatically disappears.

  Therefore, various manufacturers have proposed countermeasures when a base station leaves or disappears from a wireless network. Patent Document 1 discloses a technology in which a base station for backup is selected in advance from terminals in a wireless network and switched to a backup base station when the base station disappears. Patent Document 2 discloses a method for setting the priority order as a backup base station. Further, Patent Document 3 discloses a method in which when a base station becomes inoperable as a base station, a terminal that detects the fact transmits a beacon instead to continue the wireless network. As described above, various methods have been proposed for coping with the case where there is no longer a base station that controls the network.

JP 2004-129042 A JP 2002-223217 A JP 2007-281625 A

  However, when the base station disappears from the wireless network, the following problem occurs only by providing a base station for backup.

  For example, it is assumed that a printer equipped with a wireless communication function and a digital camera equipped with the same wireless communication function (hereinafter also referred to as “DSC (digital still camera)”) participate in the wireless network. Furthermore, it is assumed that image data in the DSC is being printed by a printer via a base station wirelessly.

At this time, the base station disappears and the backup base station becomes a base station to maintain the network. However, there is no guarantee that devices such as DSCs or printers will continue to participate in the wireless network formed by the backup base station. It can be assumed that each device detects an event that the base station has become a different device and stops network participation. Also, if there is a terminal whose main communication partner is the base station that has disappeared, if the base station that is the main communication partner disappears, it means that it is participating in the network that the backup base station is configured to There is no. Furthermore, the terminal that detects the disappearance of the base station
If the terminal simply sends a beacon instead, data transmission / reception cannot be continued. As described above, if the base station disappears while image data in the DSC is wirelessly printed on the printer via the base station in the wireless network, the printing process cannot be continued.

  As explained above, the process of providing a base station for backup when the base station disappears from the wireless network, or the process of sending a beacon instead by the terminal that detected the disappearance of the base station continued. There is a problem that there is no guarantee that data transmission and reception can be maintained without fail.

  In view of the above problems, an object of the present invention is to provide a technique for maintaining continuous data transmission / reception even when a base station leaves a wireless network.

A communication device according to the present invention that achieves the above object is as follows.
A communication device that communicates by connecting to a base station,
An acquisition means for acquiring a device identifier of a communication partner device;
Detecting means for detecting the disappearance of the base station;
When the disappearance of the base station is detected, a detecting means for detecting a communication partner apparatus that communicated before the disappearance of the base station using the device identifier obtained by the obtaining means,
When the communication partner device is detected by the detection means, either the communication device or the communication partner device newly becomes a base station, and performs processing for resuming communication between the communication device and the communication partner device. Resumption means,
It is characterized by having.

  According to the present invention, data transmission / reception can be continued even when a base station disappears from a wireless network.

The figure which shows the structural example of the communication system which concerns on this invention. 1 is a functional block diagram of a printer according to the present invention. The functional block diagram of DSC which concerns on this invention. The functional block diagram of PC concerning this invention. FIG. 2 is a sequence diagram of a printer and a DSC according to the present invention. 3 is a flowchart showing a processing procedure of the printer according to the present invention.

  In the following, an example using a wireless LAN system in conformity with the IEEE 802.11 standard will be described, but the communication form is not necessarily limited to this. A common point between the embodiments is that the wireless network is controlled by the AP. Terminals under the wireless network can perform data transmission and reception by performing communication processing via the AP. The present invention extracts only the terminals that are transmitting and receiving data, and reconstructs the wireless network only by the terminals that are transmitting and receiving data. Hereinafter, the present invention will be specifically described.

(First embodiment)
FIG. 1 is a configuration example of a wireless LAN communication system according to the present embodiment. The notebook PC 103 is activated as an AP that operates in accordance with an access point function corresponding to the IEEE 802.11 standard. A printer 101 equipped with a wireless communication function for realizing a wireless LAN function, a DSC 102 (digital still camera), a DSC 104, and a DSC 105 participate as wireless terminals in a wireless network formed by the notebook PC 103. The notebook PC 103 can print image data directly by the printer 101 wirelessly. The DSCs 102, 104, and 105 can print image data by the printer 101 via the notebook PC 103 wirelessly.

  The functional configuration of the wireless terminal in the printer 101, notebook PC 103, DSCs 102, 104, and 105 will be described with reference to FIGS. First, the functional configuration of the printer 101 will be described with reference to FIG. The printer 101 includes a printer function unit 201, a power supply unit 202, a print image transfer processing unit 203, a wireless communication function unit 204, a display processing unit 205, an operation unit 206, a CPU 207, a storage unit 208, a wireless A reconnection determination unit 209 and an access point function unit 210 are provided.

  The printer function unit 201 executes functions as a printer such as print processing. A detailed description of the function is omitted here. The power supply unit 202 supplies power to functions necessary for the printer 101 to operate, such as the printer function unit 201 and the wireless communication function unit 204. A print image transfer processing unit 203 is connected to the DSC, and controls a print image transfer protocol for realizing print processing of image data in the DSC in the printer 101. The wireless communication function unit 204 performs wireless communication in accordance with the IEEE 802.11 standard, and transmits and receives wireless signals to and from other wireless communication devices. The display processing unit 205 controls and displays information to be displayed to the user regarding the print function and the wireless function by LCD display, LED display, or the like. The operation unit 206 has an operation function for performing settings related to a print function and a wireless function. That is, the display processing unit 205 and the operation unit 206 are user I / Fs in the printer 101. The CPU 207 controls each processing unit. A program controlled by the CPU 207 is stored in a storage unit 208 configured by a RAM or a flash ROM. Communication parameters for wireless communication, device identifiers of communication partner devices described later, and the like are also stored in the storage unit 208. Data processed by the CPU 207 is also written into the storage unit 208 or read from the storage unit 208. The access point function unit 210 has a function for operating as an access point, and has a function of constructing a wireless network. Furthermore, it manages information on wireless terminals participating in the wireless network built by itself. The wireless reconnection determination unit 209 performs processing related to wireless connection when it becomes impossible to detect the AP as the connection destination. Details will be described later.

  Next, the functional configuration of the DSCs 102, 104, and 105 will be described with reference to FIG. Since the functional configuration of the DSC 102 and the functional configuration of the DSC 104 and DSC 105 are the same, the DSC 102 will be described as a representative. The DSC 102 includes a DSC function unit 301, a power supply unit 302, a print image transfer processing unit 303, a wireless communication function unit 304, a display processing unit 305, an operation unit 306, a CPU 307, a storage unit 308, and a wireless retransmission unit. A connection determination unit 309 and an access point function unit 310 are provided.

  The DSC 102 has almost the same configuration as the printer 101. The DSC 102 includes a DSC function unit 301 that processes DSC-specific functions such as imaging processing. The functions of the processing units of the power supply unit 302, the print image transfer processing unit 303, the wireless communication function unit 304, the CPU 307, the storage unit 308, the wireless reconnection determination unit 309, and the access point function unit 310 are described with reference to FIG. This is the same as the function of each processing unit of the printer 101 described. The display processing unit 305 and the operation unit 306 are also similar in function to each processing unit of the printer 101 described with reference to FIG. 2, but can display and set specific to the DSC 102.

  Next, the functional configuration of the notebook PC 103 will be described with reference to FIG. The notebook PC 103 includes a notebook PC function unit 401, a power supply unit 402, a print image transfer processing unit 403, a wireless communication function unit 404, a display processing unit 405, an operation unit 406, a CPU 407, a storage unit 408, A wireless reconnection determination unit 409 and an access point function unit 410 are provided.

  The notebook PC 103 has almost the same configuration as the printer 101. The notebook PC 103 has a notebook PC function unit 401 that processes functions specific to the notebook PC. The functions of the processing units of the power supply unit 402, the print image transfer processing unit 403, the wireless communication function unit 404, the CPU 407, the storage unit 408, the wireless reconnection determination unit 409, and the access point function unit 410 are described with reference to FIG. This is the same as the function of each processing unit of the printer 101 described. The display processing unit 405 and the operation unit 406 are also similar in function to each processing unit of the printer 101 described with reference to FIG. 2, but can display and set specific to the notebook PC 103. Heretofore, the constituent devices of the communication system in FIG. 1 have been described. In the communication system of FIG. 1, the DSCs 102, 104, and 105 can print with a printer 101 via a notebook PC 103 wirelessly. However, it is assumed that the battery of the notebook PC 103 runs out during the printing process, or the notebook PC 103 is moved out of the radio wave reach by the owner of the notebook PC 103. Under such circumstances, it is impossible to maintain the wireless network, and the printing process is interrupted. In this embodiment, even under such a situation, a printing method is continued and completed without any intervention by a DSC or printer user.

  A specific method will be described with reference to the sequence diagram of FIG. Since the processing procedure of the DSC 102 is almost the same as the processing procedure of the printer 101, description thereof is omitted.

  First, the notebook PC 103 is activated as an AP conforming to the IEEE 802.11 standard, further constructs a wireless network, and starts sending a beacon (S501). The printer 101, the DSCs 102, 104, and 105 respectively acquire communication parameters from the notebook PC 103 by executing a communication parameter automatic setting method. Communication parameters provided from the notebook PC 103 to the notebook PC 103 by the communication parameter automatic setting method include a network identifier SSID, frequency channel information used in the wireless network, an encryption method, an encryption key, an authentication method, and an authentication key. . Furthermore, the printer 101 and the DSCs 102, 104, and 105 perform wireless connection using the acquired communication parameters (S502). The printer 101 and the DSCs 102, 104, and 105 realize wireless communication via the notebook PC 103 by synchronizing with the beacon transmitted from the notebook PC 103.

  Through these steps, for example, image data in the DSC 102, 104, or 105 can be wirelessly transferred to the printer 101 via the notebook PC 103 and printed. Here, a case where image data in the DSC 102 is printed by the printer 101 will be described. DSC 104 and DSC 105 exist in the wireless network, but processing such as image printing is not executed.

  A user of the DSC 102 selects image data to be printed from image data in the DSC 102 via the display processing unit 305 and the operation unit 306. Next, print processing is executed. By this operation, processing of the print image transfer protocol is started (S503). In this process, the printer 101 stores the device identifier of the DSC 102, and the DSC 102 stores the device identifier of the printer 101 (S504, S505). Further, the printing process is executed via the print image transfer protocol (S506).

  Here, the notebook PC 103 is removed from the wireless network because the battery of the notebook PC 103 runs out during execution of the printing process or the notebook PC 103 is moved out of the wireless radio wave reach by the owner of the notebook PC 103. Suppose that (S507). The printer 101, the DSCs 102, 104, and 105 cannot detect the beacon from the notebook PC 103 that is the base station, thereby detecting that the network has disappeared (S508). At this time, since the printer 101 and the DSC 102 are continuing the printing process, an attempt is made to construct an alternative wireless network. Details are described below.

  When the printer 101 detects the disappearance of the wireless network, the wireless reconnection determination unit 209 instructs the print image transfer processing unit 203 to temporarily stop the printing process (S509). Further, the wireless reconnection determination unit 209 instructs the wireless communication function unit 204 to prepare for transmission of a search request or to prepare for reception of a search request. Specifically, the wireless reconnection determination unit 209 instructs the wireless communication function unit 204 to add its own device identifier to the search request and perform broadcast transmission (S510).

  On the other hand, when receiving the search request, the wireless reconnection determination unit 209 compares the device identifier attached to the search request with the device identifier of the communication partner stored in S505. If the device identifier comparison results are equal, the wireless reconnection determination unit 209 instructs the wireless communication function unit 204 to transmit a search response to the search request.

  Similarly, when the DSC 102 detects the disappearance of the wireless network, the wireless reconnection determination unit 309 instructs the wireless communication function unit 304 to prepare for transmission of a search request or to prepare for reception of a search request. The specific processing content is the same as that of the printer 101. Therefore, when the DSC 102 receives the search request, the DSC 102 compares the device identifier associated with the search request with the device identifier of the communication partner stored in S504. Here, both the device identifier associated with the search request and the device identifier of the communication partner stored in S504 coincide with each other because they are the printer 101. Accordingly, the DSC 102 returns a search response to the printer 101 (S511).

  Although the search request is transmitted from the printer 101 here, it may be transmitted from the DSC 102. In particular, it is not necessary to provide a regulation for transmission from either device, and the device that has detected the disappearance of the wireless network may transmit the search request. Then, the device that has received the search request confirms the device identifier and transmits a search response. Further, the device identifier may not be attached to the search request, but the device identifier may be attached to the search response, and the device identifier may be confirmed on the search response receiving side.

  Furthermore, the search request can be realized by Probe Request defined in the IEEE 802.11 standard. Further, with respect to a channel when transmitting or receiving a search request and a search response, it is necessary to devise such that these requests and responses do not pass each other. For example, it is preferable to send and receive requests and responses on a predetermined frequency channel and within a predetermined time. Further, the configuration may be such that the request and response are transmitted and received within a predetermined time after the disappearance is detected on the frequency channel on which the notebook PC 103 has transmitted the beacon, that is, the frequency channel used by the disappeared wireless network.

  After that, the printer 101 and the DSC 102 that have confirmed the existence of each other's devices need to be either APs acting as APs. Therefore, the process of determining which device is the AP is performed. The selection criteria for the AP device may be determined based on whether the access point function is installed, the remaining battery level, the processing capability of the device, and the like. In these cases, a device having an access point function is used as an access point. In addition, a device with a large amount of remaining battery is used as an access point. Alternatively, it may be determined by defining a numerical value as a reference for comparison in advance and comparing the magnitude. Further, the device that has made the search request may be determined as an AP, and the device that has made the search response may be determined as an AP. Here, it is assumed that the printer 101 is determined as an alternative access point (alternate AP, alternative base station) using any one of the determination conditions as a predetermined condition (S512).

  The printer 101 generates communication parameters for the wireless network that it constitutes (S513). Furthermore, it is activated as an AP conforming to the IEEE 802.11 standard via the access point function unit 210. The DSC 102 acquires communication parameters from the printer 101 by executing a communication parameter automatic setting method. Further, the DSC 102 performs wireless connection using the acquired communication parameter (S514). When the wireless connection is completed, the wireless reconnection determination unit 209 instructs the print image transfer processing unit 203 to resume printing (S515). The alternative wireless network for continuing the image printing process is constructed by the above process. Thereafter, the printing process interrupted by the removal of the notebook PC 103 is continued.

  Note that after the printing process is completed, the wireless connection may be disconnected (S516), and the alternative wireless network generated by the printer 101 may be canceled. This is because the behavior of the printer 101 as an alternative AP is only temporary, and there is a possibility that an adverse effect may occur if it is continuously used. For example, when the printer 101 is operated by battery power supply, the beacon is periodically transmitted, so that the battery may be consumed significantly. In addition, when the notebook PC 103 that has left earlier is restored again, it may start to act as an AP, and thus a negative effect may occur when rejoining the wireless network that the notebook PC 103 configures.

  In DSCs 104 and 105, there is no need to forcibly participate in the wireless network configured by the printer 101 as an alternative AP. For example, when the main communication partner of the DSCs 104 and 105 is the notebook PC 103, it does not make sense to participate in the wireless network configured by the printer 101 without the notebook PC 103. In the above description, communication parameters of a wireless network newly configured by the printer 101 are newly generated. In this way, a wireless network different from the wireless network configured by the notebook PC 103 is configured. Therefore, if the printer 101 does not provide communication parameters to devices other than the DSC 102, devices other than the communication target are excluded. You can configure the network. Further, the printer 101 can also use the same communication parameters as those of the wireless network configured by the notebook PC 101 without newly generating communication parameters. In this case, the DSC 102 can connect to the wireless network that the printer 101 configures without acquiring communication parameters from the printer 101.

  Next, the processing procedure of the printer 101 in the sequence diagram of FIG. 5 will be described with reference to the flowchart of FIG. The processing procedures of the DSCs 102, 104, and 105 are the same as the processing procedure of the printer 101.

  In step S <b> 601, the printer 101 realizes wireless communication via the notebook PC 103 by synchronizing with a beacon transmitted from the notebook PC 103 functioning as an AP. In step S602, the printer 101 starts a printing process.

  In step S603, the printer 101 starts processing of a print image transfer protocol. In step S604, the printer 101 stores the device identifier of the DSC 102 that is the communication partner.

  In step S <b> 605, the printer 101 determines whether the print image transfer process using the print image transfer protocol has been completed. If it is determined that the print image transfer process has been completed (S605; YES), the process proceeds to S616. On the other hand, if it is determined that the print image transfer process has not been completed (S605; NO), the process proceeds to S606.

  In step S <b> 606, the printer 101 determines whether the notebook PC 103 functioning as an AP has left the wireless network based on whether or not a beacon is detected. When it is determined that the notebook PC 103 has left the wireless network (S606; YES), the process proceeds to S607. On the other hand, when it is determined that the notebook PC 103 has not left the wireless network (S606; NO), the process returns to S605.

  In step S <b> 607, the wireless reconnection determination unit 209 of the printer 101 instructs the print image transfer processing unit 203 to temporarily stop print processing. In step S <b> 608, the wireless reconnection determination unit 209 of the printer 101 further instructs the wireless communication function unit 204 to prepare for transmitting a search request. Specifically, the search request is transmitted by instructing the wireless communication function unit 204 to add the device identifier of the printer 101 to the search request and perform transmission by broadcast.

  In step S609, the wireless reconnection determination unit 209 of the printer 101 compares the device identifier attached to the search request with the device identifier of the communication partner stored in step S604 when receiving the search request from the DSC 102, for example. It is determined whether or not both match. If it is determined that both match (S609; YES), the process proceeds to S610. On the other hand, when it is determined that the two do not match or when the search request is not received (S609; NO), the process proceeds to S611.

  In step S610, the wireless reconnection determination unit 209 of the printer 101 instructs the wireless communication function unit 204 to transmit a search response to the search request received in step S609, and the wireless communication function unit 204 transmits the search response. Thereafter, the process proceeds to S612.

  In step S611, the printer 101 determines whether a search response to the search request transmitted in step S608 has been received. When it is determined that the search response has been received (S611; YES), the process proceeds to S612. On the other hand, when it is determined that the search response has not been received within the predetermined time (S611; NO), the process proceeds to S616.

  In step S612, the printer 101 determines which one of the communication partners is to operate as an AP. The determination criteria at this time are as described with reference to the sequence diagram of FIG.

  In step S <b> 613, the printer 101 performs wireless network parameter determination processing used with the DSC 102. In step S614, the printer 101 establishes a wireless network using the parameters determined in step S613. In addition, the DSC 102 acquires communication parameters from the printer 101 and connects to the wireless network of the printer 101. In step S615, the printer 101 resumes communication after wirelessly connecting to the DSC 102, and resumes the temporarily stopped printing process. Thereafter, the process returns to S605.

  In step S616, the printer 101 deletes the device identifier of the DSC 102 that is the communication partner stored in step S604. In step S617, a process for cutting the transfer of the print image is performed. Thus, each process of the flowchart of FIG. 6 ends.

  As described above, when the DSC 102 wirelessly prints to the printer 101 via the notebook PC 103, even if the wireless network constituted by the notebook PC 103 and the notebook PC 103 disappears, there is no need for any user processing. The camera image printing process can be continued.

  In addition, by not re-joining all the terminals existing in the extinguished wireless network to the alternative wireless network, there is an advantage that a power saving effect can be obtained for a terminal in which data communication by the wireless network is not urgent.

  In the above description, the case where the communication partner of the printer 101 is the DSC 102 has been described. Next, a case where the communication partner of the printer 101 is the notebook PC 103 will be described. That is, the notebook PC 103, which is the communication partner of the printer 101, and the access point are the same device. A case where the communication partner of the printer 101 is an external network terminal connected to the notebook PC 103 by wire, for example, will be described.

  The processing procedure of the printer 101 will be described below with reference to the flowchart of FIG.

  In step S601, since the notebook PC 103 and the printer 101 are APs, the notebook PC 103 is in a state in which image data existing in the notebook PC 103 can be directly transferred to the printer 101 and printed. A user of the notebook PC 103 selects data to be printed such as image data in the notebook PC 103 via the display processing unit 305 and the operation unit 306. In step S602, the printer 101 executes print processing. In step S603, the printer 101 starts processing of a print image transfer protocol by this operation.

  In step S604, in the process of step S603, the printer 101 stores the device identifier of the notebook PC 103, while the notebook PC 103 stores the device identifier of the printer 101. Thereafter, a printing process is executed via the print image transfer protocol. The procedure so far is almost the same as the above-described procedure. In other words, the communication partner device of the printer 101 is the notebook PC 103 instead of the DSC 102, and the printer 101 and the notebook PC 103 are the same except that the printing process is directly performed wirelessly.

  In step S <b> 605, the printer 101 determines whether the print image transfer process using the print image transfer protocol has been completed. If it is determined that the print image transfer process has been completed (S605; YES), the process proceeds to S616. On the other hand, if it is determined that the print image transfer process has not been completed (S605; NO), the process proceeds to S606.

  In step S <b> 606, the printer 101 determines that the notebook PC 103 has run out of wireless radio wave due to the battery running out of the notebook PC 103 or the notebook PC 103 has been moved out of the wireless radio wave reach by the owner of the notebook PC 103. Determines whether or not the wireless network has left the wireless network. The printer 101 detects that the wireless network has disappeared based on whether or not a beacon is detected. At this time, since the printer 101 is continuing the printing process, it tries to construct an alternative wireless network. Details are described below.

  In step S <b> 607, when the printer 101 detects the disappearance of the wireless network, the wireless reconnection determination unit 209 instructs the print image transfer processing unit 203 to temporarily stop the process. In step S <b> 608, the wireless reconnection determination unit 209 of the printer 101 further instructs the wireless communication function unit 204 to prepare for transmitting a search request. Specifically, the wireless reconnection determination unit 209 instructs the wireless communication function unit 204 to add the device identifier of the printer 101 to the search request and perform broadcast transmission.

  Since the notebook PC 103 which is the communication partner of the printer 101 has disappeared, the printer 101 proceeds to S611 without receiving a search request in S609. Furthermore, since the search response from the notebook PC 103 to the search request transmitted by the printer 101 is not received, the process proceeds to S616.

  In step S616, therefore, the printer 101 gives up reconfiguration of the wireless network and deletes the stored device identifier. In step S617, the wireless reconnection determination unit 209 of the printer 101 instructs the print image transfer processing unit 203 to interrupt the print transfer process.

  Even when the communication partner of the printer 101 is, for example, an external network terminal connected to the notebook PC 103 by wire, the external network terminal cannot respond to the search request transmitted by the printer 101 and cannot transmit a search response to the printer 101. . Therefore, the result is the same as when the communication partner is the notebook PC 103.

  As described above, even when the wireless network disappears due to the absence of the AP during the printing process in the printer 101, if the partner of the printing process is the AP, an alternative wireless network is constructed. Absent. By this process, there is an effect of constructing a useless wireless network and suppressing useless power consumption of a device activated as an alternative AP.

  As described above, even when the base station disappears from the wireless network, data transmission / reception before the base station disappears can be continued. For example, it is possible to solve the problem in the case where the base station disappears while the communication apparatus is wirelessly connected to the base station and printing processing is performed on the printer. Specifically, by configuring a wireless network between a communication device that is communicating data at the time of such an event and its counterpart device, reliable data communication is continued and user convenience is improved. Can be made. Also, with the disappearance of base stations, all communication devices existing in the disappeared wireless network are not re-joined to the alternative wireless network, thereby obtaining a power saving effect for terminals that are not urgently required for data communication via the wireless network. The effect that it can be also obtained. In addition, if the communication partner of the printer or the printer itself is a base station, if that base station disappears, construction of a useless wireless network and suppression of useless power consumption of devices activated as alternative base stations There is an effect.

(Other embodiments)
The present invention can also be realized by executing the following processing. That is, software (program) that realizes the functions of the above-described embodiments is supplied to a system or apparatus via a network or various storage media, and a computer (or CPU, MPU, or the like) of the system or apparatus reads the program. It is a process to be executed.

Claims (7)

A communication device that communicates by connecting to a base station,
An acquisition means for acquiring a device identifier of a communication partner device;
Detecting means for detecting the disappearance of the base station;
When the disappearance of the base station is detected, a detecting means for detecting a communication partner apparatus that communicated before the disappearance of the base station using the device identifier obtained by the obtaining means,
When the communication partner device is detected by the detection means, one of the communication device and the communication partner device becomes a new base station, and communication between the communication device and the communication partner device is resumed. Resuming means for processing,
A communication apparatus comprising: A transmission means for transmitting a search request when the disappearance of the base station is detected;
Receiving means for receiving a search response to the search request;
The communication device according to claim 1, wherein the detection unit detects the communication partner device based on a device identifier included in the search request or the search response. When the communication partner device is detected by the detection unit, the communication partner device further includes a determination unit that determines either the communication device or the communication partner device as an alternative base station according to a predetermined condition,
The said restarting means restarts the communication between the said communication apparatus and the said communicating party apparatus via the wireless network comprised by the alternative base station determined by the said determination means. Item 3. The communication device according to Item 2.   The apparatus according to claim 1, further comprising: an erasing unit that erases the device identifier of the communication counterpart device acquired and stored by the acquisition unit when the communication counterpart device is not detected by the detection unit. Communication device.   The communication apparatus according to claim 1, wherein the communication apparatus is a digital camera or a printer. A control method of a communication apparatus comprising a control means, a detection means, a detection means, and a restart means, and communicates by connecting to a base station,
The control unit acquires an apparatus identifier of a communication partner device;
A detection step in which the detection means detects the disappearance of the base station;
When the detection means detects the disappearance of the base station, a detection step of detecting a communication partner apparatus communicating before the disappearance of the base station using the device identifier acquired in the acquisition step;
When the restarting unit detects the communication partner device in the detection step, either the communication device or the communication partner device newly becomes a base station, and between the communication device and the communication partner device. A resuming step for performing processing for resuming communication;
A method for controlling a communication apparatus, comprising:   The program for making a computer perform each process of the control method of the communication apparatus of Claim 6.