Communication device, control method, and program

Abstract

In a communication device that uses multiple communication interfaces capable of utilizing frequency channels in the DFS band that require Dynamic Frequency Selection (DFS) support, the channels to be used are appropriately configured. [Solution] When a communication device (access point (AP), imaging device, and information communication terminal) that communicates using multiple communication interfaces is performing parallel communication with the AP using a first communication interface and communication using a second communication interface of the Wi-Fi Direct® standard as a station, if the first communication interface is using a frequency channel that requires DFS support and receives a change of frequency channel from the AP, and the second communication interface is using a frequency channel in the same predetermined frequency band as the first communication interface, the frequency channel of each communication interface is changed.

Description

Technical Field

[0001] The present invention relates to a channel setting technique used in a wireless LAN compliant with the IEEE802.11 series standards.

Background Art

[0002] Currently, wireless Local Area Networks (LANs) represented by the IEEE (Institute of Electrical and Electronics Engineers) 802.11 series standards are widely used. In a wireless LAN, various frequency bands can be utilized, including frequency bands where interference with other systems such as weather radar and aviation radar may occur. On the other hand, communication devices using frequency bands where such interference with other systems may occur need to support a mechanism called DFS (Dynamic Frequency Selection) that switches the frequency channel in use to another frequency channel in response to detecting a signal from another system. Note that DFS is an abbreviation for Dynamic Frequency Selection. Wireless LAN access points (APs) and stations (STAs) that do not support DFS cannot use predetermined frequency channels such as W53 and W56 in the 5 GHz band, for example. Hereinafter, a frequency band that requires DFS support such as W53 or W56 may be referred to as a DFS band.

[0003] Furthermore, the Wi-Fi® Alliance has developed the Wi-Fi Direct (WFD) standard, which defines a procedure for establishing a communication link between STAs by exchanging communication parameters without going through an AP. In the previous standard, WFD Release 1 (R1), a Group Owner (GO), which acts as an AP, could not use DFS band channels in WFD communication. On the other hand, in WFD Release 2 (R2), if an STA is connected to an AP operating on a DFS band channel using a first communication interface (I / F), it is permitted to function as a GO using the same channel on another communication I / F. In other words, in WFD R2, if a communication device with multiple communication I / Fs is connected to an AP as an STA on a DFS band channel, it can use the DFS band as a GO by setting the operating channel as that channel. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2013-251926 [Overview of the project] [Problems that the invention aims to solve]

[0005] Patent Document 1 describes a method for setting frequency channels in a communication device when a DFS band radar signal is detected on multiple different frequency channels used in each of multiple communication interfaces. However, as mentioned above, WFD R2 has constraints such as the need to use the same frequency channel as STA when using DFS in GO, and an efficient method for setting frequency channels that takes such constraints into account has not been considered. [Means for solving the problem]

[0006] The present invention provides a technique for appropriately setting the channels used in a communication device that uses multiple communication interfaces capable of utilizing frequency channels in the DFS band.

[0007] A communication device according to one aspect of the present invention includes: communication means capable of performing communication compliant with the IEEE 802.11 standard series using a plurality of communication interfaces; and, in a case where communication is performed in parallel with an access point (AP) as a station (STA) using a first communication interface and with another device functioning as a Client (CL) as a Group Owner (GO) of the Wi-Fi Direct (WFD) standard using a second communication interface, and when the first communication interface is using a frequency channel in a predetermined frequency band that requires support for Dynamic Frequency Selection (DFS) functionality, a first wireless frame indicating a change in the frequency channel to be used is received from the AP, and the second communication interface is used to check whether the same predetermined frequency band and frequency channel as the first communication interface is being used; and, if it is confirmed that the second communication interface is using the same predetermined frequency band and frequency channel as the first communication interface, a change means for changing the frequency channels of the first and second communication interfaces based on the first wireless frame. [Effects of the Invention]

[0008] According to the present invention, in a communication device that uses multiple communication interfaces capable of using frequency channels in the DFS band, it becomes possible to appropriately set the channels to be used. [Brief explanation of the drawing]

[0009] [Figure 1] This figure shows an example of a system configuration. [Figure 2] This figure shows an example of the hardware configuration of a communication device. [Figure 3]This figure shows an example of the functional configuration of a communication device. [Figure 4] This is a diagram illustrating the configuration of the CSA Element. [Figure 5] This diagram shows an example of the communication control flow in a system. [Figure 6] This diagram shows an example of the channel change process performed in a communication device. [Figure 7] This diagram shows an example of the communication control flow in a system. [Figure 8] This diagram shows an example of the channel change process performed in a communication device. [Figure 9] This diagram shows an example of the communication control flow in a system. [Figure 10] This diagram shows an example of the channel change process performed in a communication device. [Modes for carrying out the invention]

[0010] The embodiments will be described in detail below with reference to the attached drawings. Note that the following embodiments do not limit the invention as defined in the claims. While the embodiments describe multiple features, not all of these features are essential to the invention, and the features may be combined in any way. Furthermore, in the attached drawings, identical or similar configurations are given the same reference numerals, and redundant descriptions are omitted.

[0011] (System Configuration) Figure 1 shows an example configuration of a wireless communication system according to this embodiment. This wireless communication system includes an access point (AP101), an imaging device 102, and an information and communication terminal 103, each of which is a communication device. The AP101, imaging device 102, and information and communication terminal 103 are configured to perform wireless communication compliant with the IEEE 802.11 standard series, such as the IEEE 802.11bn standard, or earlier or subsequent standards. IEEE stands for Institute of Electrical and Electronics Engineers. The imaging device 102 is configured to perform communication compliant with the IEEE 802.11 standard series as a station (STA) in a first network 111 formed by the AP101, for example. The imaging device 102 also has Wi-Fi Direct (WFD) communication capabilities and is configured to form a second network 112 as a WFD P2P Group Owner (P2P GO). The information and communication terminal 103 functions as a WFD P2P Client (P2P CL) and connects to the imaging device 102, which functions as a P2P GO, to perform wireless communication compliant with WFD. In the following, P2P GO may be simply referred to as GO, and P2P CL may be simply referred to as CL. In this embodiment, the imaging device 102 operates the STA function and the GO function in parallel (simultaneously), connecting to AP101 as an STA while connecting to the information and communication terminal 103 as a GO. The imaging device 102 may individually set the channel (frequency channel) used for GO and the channel used to connect to AP101 as an STA. That is, the imaging device 102 may use the same channel for the GO function and the STA function, or it may use different channels for each. In this embodiment, the imaging device and information and communication terminal are shown as examples, but other devices with similar communication functions may be used. For example, a smartphone, tablet, personal computer (PC), video camera, etc. may be used instead of the imaging device 102.

[0012] In this embodiment, as described above, the imaging device 102 connects to AP 101 as an STA using multiple communication interfaces, forms a second network 112 as a GO, and connects to an information communication terminal 103 operating as a CL. At this time, the imaging device 102 can use the DFS band in the second network 112, provided that the first network 111 is using a frequency channel in the Dynamic Frequency Selection (DFS) band. In this embodiment, the DFS band refers to a predetermined frequency band such as W53 or W56 that requires DFS support, and below, frequency bands that do not require DFS support may be referred to as non-DFS bands. In this case, the second network 112 must use the same frequency channel as the one used in the first network 111. When AP 101 or the imaging device 102 is connected to the first network 111 using a frequency channel in the DFS band and detects a radar signal on that frequency channel, the frequency channel of the first network 111 is changed using the DFS function. In this case, if the imaging device 102 is also using DFS band frequency channels in the second network 112, it is necessary to change the frequency channel in the second network 112 as well. That is, if the imaging device 102 is using DFS band frequency channels in the second network 112, it is necessary to change the channel in the second network 112 when the channel in the first network 111 is changed. On the other hand, if the second network 112 is using non-DFS band frequency channels, changing the channel in the second network 112 in response to a channel change in the first network 111 may reduce efficiency due to unnecessary changes in the channels used. In view of these circumstances, this embodiment provides an appropriate channel setting technique for a communication device using multiple communication interfaces that can utilize DFS band frequency channels.

[0013] (Device configuration) Figure 2 shows an example of the hardware configuration of the communication device (AP101, imaging device 102, information communication terminal 103) according to this embodiment. As shown in Figure 2, the communication device includes, for example, a storage unit 201, a control unit 202, a function unit 203, an input unit 204, an output unit 205, a communication unit 206, and an antenna 207 as its hardware configuration.

[0014] The storage unit 201 is configured to include one or more memories, such as ROM or RAM, and stores various information, such as computer programs for performing various operations described later, and communication parameters for wireless communication. ROM stands for Read Only Memory, and RAM stands for Random Access Memory. In addition to or instead of ROM or RAM, the storage unit 201 may include storage media such as flexible disks, hard disks, optical disks, magneto-optical disks, CD-ROMs, CD-Rs, magnetic tapes, non-volatile memory cards, and DVDs. The storage unit 201 may also include a Solid State Drive (SSD). Furthermore, the storage unit 201 may include multiple memories.

[0015] The control unit 202 is composed of one or more processors such as a CPU or MPU, and controls the entire communication device by executing, for example, a computer program stored in the storage unit 201. Note that CPU is an abbreviation for Central Processing Unit, and MPU is an abbreviation for Micro Processing Unit. In addition to controlling the entire communication device, the control unit 202 may be configured to execute a process of generating data and signals (radio frames) to be transmitted in communication with other communication devices. Note that the control unit 202 may be configured to execute processes such as controlling the entire communication device through cooperation between, for example, a computer program stored in the storage unit 201 and an OS (Operating System). Further, the control unit 202 may include a plurality of processors such as a multi-core, and execute processes such as controlling the entire communication device by the plurality of processors. Further, the control unit 202 may be composed of an ASIC (Application Specific Integrated Circuit), a DSP (Digital Signal Processor), an FPGA (Field Programmable Gate Array), or the like.

[0016] Furthermore, the control unit 202 controls the functional unit 203 to perform predetermined processes such as imaging, printing, and projection. The functional unit 203 is hardware for the communication device to perform predetermined processes. For example, in the imaging device 102 or the information communication terminal 103, the functional unit 203 may be the imaging unit, which performs imaging of the surrounding image. Also, for example, if the communication device is a printer, the functional unit 203 is the printing unit, which performs printing on a sheet such as paper based on print data stored in the storage unit 201 or acquired from an external source via wireless communication. Also, for example, if the communication device is a projector or smart glasses, the functional unit 203 is the projection unit, which performs projection of image data or video data stored in the storage unit 201 or acquired from an external source via wireless communication. In the case of smart glasses, the projection surface is the end user's retina, etc. The data processed by the functional unit 203 may be data stored in the storage unit 201, or data communicated with other communication devices via the communication unit 206, which will be described later. Furthermore, communication devices can also provide network storage functionality, such as NAS (Network Attached Storage). This functionality is provided to other communication devices as a web service, such as a network storage service. For example, another communication device can connect to the network storage service provided by the communication device using protocols such as SMB, FTP, or WebDAV. The other communication device can then upload files to or download files from that storage service.

[0017] The input unit 204 receives various operations from the user. The output unit 205 provides various outputs to the user. Here, the output from the output unit 205 includes at least one of the following: display on a screen, audio output from a speaker, vibration output, etc. Note that both the input unit 204 and the output unit 205 may be implemented in a single module, such as a touch panel. Furthermore, the input unit 204 and the output unit 205 may be built into the communication device, or they may be configured as external devices connected to the communication device.

[0018] The communication unit 206 controls wireless communication compliant with the IEEE 802.11 standard series such as the IEEE 802.11bn standard, its previous standards, or successor standards, and controls Internet Protocol (IP) communication. The communication unit 206, for example, collaborates with the antenna 207 to execute transmission and reception of wireless frames compliant with the IEEE 802.11 standard series. For example, the communication units 206 of the imaging device 102 and the information communication terminal 103 may be configured to also control wireless communication compliant with the WFD standard. The communication unit 206 may be configured to be capable of executing communication in a plurality of frequency bands such as the sub-GHz band, 2.4 GHz band, 5 GHz band, 6 GHz band, 7 GHz band, and the 60 GHz band in order to perform wireless communication compliant with the IEEE 802.11 standard series or the WFD standard. Also, the communication unit 206 can communicate using bandwidths of 20 GHz, 40 MHz, 80 MHz, 160 MHz, and 320 MHz. Further, the communication unit 206 may be configured to be able to execute communication using bandwidths such as 240 MHz and 4 MHz. The imaging device 102 may have, for example, a communication unit 206 for connecting to and communicating with the AP 101 as a STA, and a communication unit 206 for functioning as a WFD GO and communicating with the information communication terminal 103. Similarly, the information communication terminal 103 may also have a communication unit 206 for WFD and a communication unit 206 for communication with the AP 101. That is, the communication device may have a plurality of communication units 206 (communication interfaces). Note that a plurality of communication interfaces may be provided by one communication unit 206.

[0019] The antenna 207 is an antenna capable of transmitting and receiving signals in at least any one of the frequency bands such as the sub-GHz band, 2.4 GHz band, 5 GHz band, 6 GHz band, 7 GHz band, and 60 GHz band. In the present embodiment, one antenna 207 is shown, but the number of antennas may be two or more. In one example, different antennas may be prepared for each frequency band. Also, when the communication device has a plurality of antennas, it may have a plurality of communication units 206 respectively corresponding to the plurality of antennas.

[0020] Furthermore, the communication unit 206 may support other communication standards in addition to the IEEE 802.11 standard series and WFD standard, such as Bluetooth®, NFC, UWB, ZigBee, and MBOA. UWB is an abbreviation for Ultra Wide Band, and MBOA is an abbreviation for Multi Band OFDM Alliance. NFC is an abbreviation for Near Field Communication. UWB includes wireless USB, wireless 1394, WiNET, etc. It may also support wired communication standards such as wired LAN. If the communication device supports the above-mentioned NFC standard, Bluetooth® standard, or wired communication standard, a communication unit 206 configured to control communication in accordance with these communication standards may be provided. The communication unit 206 and antenna 207 may be provided as an integrated component, or they may be provided as separate components.

[0021] Next, an example of the functional configuration of the communication device (AP101, imaging device 102, information communication terminal 103) according to this embodiment will be described using Figure 3. The communication device is configured to include a control processing unit 301, a memory control unit 302, a display unit 303, a first communication unit 304, a second communication unit 305, a CSA element generation unit 306, a channel usage confirmation unit 307, an operation unit 308, and an imaging unit 309. CSA stands for Channel Switch Announcement. These functions can be realized, for example, by the control unit 202 executing a program stored in the memory unit 201, or by the processing function unit in the communication unit 206. Figure 3 is a diagram illustrating the main functions of the communication device in this embodiment, and other functions are omitted. Therefore, the communication device may naturally have functions for establishing a connection with a partner device as a normal AP or STA, functions for control for communication, and functions that communication devices generally have. Furthermore, multiple functional blocks in Figure 3 may be integrated into a single functional block, or a single functional block may be divided into multiple functional blocks.

[0022] The control processing unit 301 controls each part of the communication device according to the input signals and the program described later. The control processing unit 301 controls not only the internal workings of the device but also wireless communication. Alternatively, instead of the control processing unit 301 controlling the entire device, the entire device may be controlled by multiple hardware components sharing the processing. The memory control unit 302 stores information such as the control program executed by the control processing unit 301 and communication-related parameters such as the Traffic Identifier (TID) and link IDs for identifying one or more links. Various operations described later can be realized by the control processing unit 301 executing the control program stored in the memory control unit 302. The display unit 303 provides information such as character display for interactive operation and on / off / on / off indicator lights. The display unit 303 of the imaging device 102 and the information communication terminal 103 can also be configured to display, for example, the viewfinder image during shooting and the captured image data.

[0023] The first communication unit 304 and the second communication unit 305 are wireless communication interfaces for communicating with external devices. The first communication unit 304 and the second communication unit 305 can be configured to perform wireless communication compliant with the IEEE 802.11 standard series, including the IEEE 802.11bn standard, and the WFD standard. The first communication unit 304 and the second communication unit 305 may each be implemented using separate communication units 206, or both the first communication unit 304 and the second communication unit 305 may be implemented using a single communication unit 206. In one example, the first communication unit 304 and the second communication unit 305 are configured to communicate using separate antennas 207. In another example, the first communication unit 304 and the second communication unit 305 may communicate using a common antenna, provided that they have the capability to separate the signals received in their respective communications by means of a filter or the like. Furthermore, a common antenna may be used by the control processing unit 301 to rapidly switch between the first communication unit 304 and the second communication unit 305 using Dynamic Rapid Channel Switching (DRCS). In this embodiment, the imaging device 102 communicates with AP 101 using the first communication unit 304 and with the information communication terminal 103 using the second communication unit 305. In the following description, AP 101 and the information communication terminal 103 each communicate with the imaging device 102, but they can communicate with other devices using multiple communication interfaces such as the first communication unit 304 and the second communication unit 305. Also, AP 101 and the information communication terminal 103 may have only one communication interface. In addition, each communication device may have three or more communication interfaces (for example, a third communication unit (not shown)). In this embodiment, the imaging device 102 operates multiple communication interfaces in parallel (simultaneously) using the first communication unit 304 and the second communication unit 305.

[0024] The CSA Element generation unit 306 generates a Channel Switch Announcement (CSA) Element, which is an information element used by APs and GOs to notify the STA that a channel change should be made. The CSA Element generation unit 306 includes this CSA Element in the Beacon frame or Probe Response frame and sends it. The CSA Element will be described later.

[0025] The channel usage confirmation unit 307 performs a check on the frequency channel being used. For example, when the imaging device 102 receives a CSA from AP101, the channel usage confirmation unit 307 checks whether the frequency channel used for P2P GO is the same as the frequency channel used for communication with AP101. The channel usage confirmation unit 307 can also check whether the frequency channel used by P2P GO is a frequency channel in the DFS band. In one example, the channel usage confirmation unit 307 provides the result of the check to the first communication unit 304 or the second communication unit 305. This allows the first communication unit 304 and the second communication unit 305 to control the setting of the channel being used based on the result of this check.

[0026] The operation unit 308 is used to receive user operations. The operation unit 308 detects user operations on user interfaces such as a power button for instructing the ON / OFF of the communication device, a release button for instructing shooting, and a playback button for instructing the playback of image data. The operation unit 308 also detects user operations on operating elements such as dedicated connection buttons for starting communication with other communication devices via the first communication unit 304 and the second communication unit 305, if such elements exist. When the operation unit 308 detects a user operation, it notifies the control processing unit 301 of the detection result, and the control processing unit 301 controls each functional unit in response to the notification. The imaging unit 309 controls, for example, an optical system that controls the optical lens unit, aperture, zoom, focus, etc., and an image sensor that converts the light (image) introduced through the optical lens unit into an electrical image signal. The image sensor may be composed of, for example, a CMOS (Complementary Metal Oxide Semiconductor) or a CCD (Charge Coupled Device). Image data generated by the imaging unit 309 may, in one example, be transmitted to other communication devices via the first communication unit 304 or the second communication unit 305.

[0027] Next, we will explain an example of the configuration of a Channel Switch Announcement (CSA) Element using Figure 4. A CSA Element consists of Element ID 401, Length 402, Channel Switch Mode 403, New Channel Number 404, and Channel Switch Count 405. Element ID 401 stores an identifier (ID) indicating that this information element is a CSA. Length 402 stores a value indicating the length of this information element. Channel Switch Mode 403 stores either 0 or 1 as information indicating restrictions on the transmission of wireless frames until the channel is changed. If Channel Switch Mode 403 is set to "0", it indicates that there are no restrictions, and if it is set to "1", it indicates that there is a restriction that prevents the transmission of wireless frames until the channel change is complete. New Channel Number 404 stores a value indicating the new channel number. Channel Switch Count 405 stores a value indicating the timing of the channel switch. This timing value is expressed using TBTT (Target Beacon Transmit Time), which is the timing at which the AP periodically transmits Beacon frames. For example, if "1" is stored in Channel Switch Count 405, it indicates that the channel will be switched at the next Beacon transmission timing. On the other hand, if "0" is stored in Channel Switch Count 405, it indicates that the channel will be switched at any time. The CSA Element generation unit 306 generates a CSA Element with such a configuration, and the first communication unit 304 or the second communication unit 305 can include this CSA Element in the wireless frame and transmit it.

[0028] (Process flow) Next, an example of the processing flow performed in the wireless communication system of this embodiment will be described.

[0029] <Processing Example 1> Figure 5 shows an example of the communication control flow when the channel between the imaging device 102 and AP101 is changed while the imaging device 102 is operating multiple communication interfaces in parallel. In Figure 5, the imaging device 102 is assumed to connect to AP101 as an STA using the first communication interface and to connect to the information communication terminal 103 as a GO using the second communication interface. For example, the imaging device 102 may connect to AP101 as an STA using the first communication unit 304 and, in parallel, operate as a GO using the second communication unit 305. Here, the imaging device 102 is assumed to be using the same frequency channel in the DFS band for both the first and second communication interfaces.

[0030] In this state, when AP101 detects a radar signal via DFS (S501), it starts the process of changing the frequency channel to be used. AP101 transmits a CSA to the imaging device 102 connected as an STA (S502). Here, AP101 may transmit the CSA Element in a Beacon frame, for example. Also, when AP101 receives a Probe Request frame from an unconnected STA, it may transmit the CSA Element in a Probe Response frame, which is the response. AP101 may also transmit the CSA Element in another radio frame, such as an Action frame. Alternatively, AP101 may transmit an information element with a different name containing similar information for changing the channel, instead of a CSA Element, in a radio frame.

[0031] The imaging device 102 receives a wireless frame containing a CSA element, for example, via the first communication unit 304. The imaging device 102 then controls the channel usage confirmation unit 307, for example, via the control processing unit 301, to confirm the channel currently in use (S503). For example, the imaging device 102 checks whether the second communication unit 305, which is operating as GO, is using the same frequency channel as the first communication unit 304 (before the change). The imaging device 102 also checks whether the frequency channel is in the DFS band if the second communication unit 305 and the first communication unit 304 are using the same frequency channel. If the imaging device 102 confirms that the first communication unit 304 and the second communication unit 305 are using the same channel in the DFS band, it executes a process to change the frequency channel used by the second communication unit 305. That is, the imaging device 102 checks the CSA element in the received wireless frame in S502 (S504). This verification may be performed at any point in time, provided that the frequency channel used as STA can be changed in a timely manner, and the frequency channel used as GO can be changed as necessary. For example, this verification may be performed at the time the radio frame is received in S502.

[0032] The imaging device 102 generates a CSA Element to be transmitted as GO using the CSA Element generation unit 306. For example, the imaging device 102 sets the content of the CSA Element to be transmitted based on the Channel Switch Count confirmed in S504 (S505). In one example, the imaging device 102 first identifies the timing at which the channel will be changed in the first communication unit 304 based on the Channel Switch Count confirmed in S504 and the Beacon interval transmitted from AP 101. Then, the imaging device 102 determines the value of the Channel Switch Count to be set in the CSA Element transmitted by itself so that the channel of the second communication unit 305 is changed at a timing earlier than the identified timing. In other words, in WFD R2, a communication device operating as GO cannot use a DFS band frequency channel unless it is using a DFS band frequency channel on a communication interface other than the communication interface operating as GO. Therefore, the imaging device 102 sets the Channel Switch Count value so that the frequency channel used as GO is changed before or at the same time as the frequency channel used as STA is changed. Then, the imaging device 102 transmits a CSA including the Channel Switch Count set in S505 to the information communication terminal 103 via the second communication unit 305 which is functioning as GO (S506). The imaging device 102 transmits the CSA Element in wireless frames such as Beacon frames, Probe Response frames, and Action frames, for example.

[0033] Then, the imaging device 102 transmits Beacon frames in the second communication unit 305 a number of times indicated by the Channel Switch Count set in S505, and then changes the channel used in the second communication unit 305 (S507). The information communication terminal 103 analyzes the CSA Element received in S506 to determine the value of the Channel Switch Count. Then, the information communication terminal 103 waits until Beacon frames are transmitted from the imaging device 102 a number of times indicated by that value, and then changes the channel used to the channel indicated by the CSA Element (S508). Note that in S507 and S508, the channel used is changed after the imaging device 102 transmits Beacon frames a number of times set in S505, based on the timing when the CSA was transmitted in S506.

[0034] Subsequently, AP101 transmits Beacon frames a number of times indicated by the Channel Switch Count in the CSA Element transmitted in S502, and then changes the channel it uses (S509). Similarly, imaging device 102 changes the channel it uses after receiving Beacon frames from AP101 a number of times indicated by the Channel Switch Count in the CSA Element confirmed in S504 (S510). Note that in S509 and S510, the channel change is performed after AP101 transmits Beacon frames a number of times specified in the CSA, based on the timing of the CSA transmission in S502.

[0035] An example of the processing flow performed by the imaging device 102 will be explained using Figure 6. Note that the following processing can be performed by any communication device having multiple wireless communication interfaces, and which functions as a GO using a second interface while connecting to other communication devices via the first interface. That is, although the imaging device 102 is used as an example, other communication devices may perform similar processing. Note that the following processing can be achieved, for example, by the control unit 202 executing a program stored in the storage unit 201, or by the control unit 202 or the communication unit 206 executing programs pre-stored within themselves. Note that the functional units that perform each processing step described below are examples, and each processing may be performed by other functional units.

[0036] The imaging device 102 receives a wireless frame containing a CSA element from AP 101 via the first communication unit 304 (YES in S601). The first communication unit 304 then notifies the control processing unit 301 that the CSA has been received. The control processing unit 301, via the channel usage confirmation unit 307, confirms whether the frequency channels used by the first communication unit 304 and the second communication unit 305 are the same frequency channel and whether they are DFS band frequency channels (S602). If the first communication unit 304 and the second communication unit 305 are using different frequency channels or are using non-DFS band frequency channels (NO in S602), the control processing unit 301 performs control to change only the frequency channel of the first communication unit 304 (S607). In other words, the control processing unit 301 performs control to change the channel of the first communication unit 304 after the time required for AP101 to transmit Beacon frames a number of times indicated by the Channel Switch Count obtained in S601 has elapsed (S607).

[0037] If the first communication unit 304 and the second communication unit 305 are using the same frequency channel in the DFS band (YES in S602), the control processing unit 301 sets the Channel Switch Count via the CSA Element generation unit 306 (S603). The value set here may be determined based on the Channel Switch Count included in the CSA Element of the wireless frame acquired in S601 and the transmission interval of the Beacon frames of the GO of AP 101 and imaging device 102. That is, the timing of when the first communication unit 304 changes channels is first identified, and the Channel Switch Count is set so that the channel of the second communication unit 305 changes at a timing earlier than the identified timing. Once the Channel Switch Count is set, the control processing unit 301 decides to set the channel to be set for the second communication unit 305, which operates as GO, to be the same channel as the channel changed by the first communication unit 304 (S604). This is just one example, and the second communication unit 305 may use a different channel from the modified channel of the first communication unit 304, as described later. However, if the second communication unit 305 uses a different channel from the first communication unit 304, the second communication unit 305 cannot use a channel in the DFS band. On the other hand, if the second communication unit 305 uses the same channel as the modified channel of the first communication unit 304, and the first communication unit 304 uses a DFS band channel different from the channel before the change, the second communication unit 305 can also use that DFS band channel.

[0038] The control processing unit 301 transmits a wireless frame containing a CSA Element with the Channel Switch Count set in S603 to the information communication terminal 103 via the second communication unit 305 (S605). The control processing unit 301 controls the second communication unit 305 to change the channel after it has transmitted Beacon frames the number of times indicated by the Channel Switch Count set in S603 (S606). Subsequently, the control processing unit 301 controls the first communication unit 304 to change the channel after the time required for AP101 to transmit Beacon frames the number of times indicated by the Channel Switch Count obtained in S601 has elapsed (S607).

[0039] As described above, in this processing example, the imaging device 102, which operates multiple communication interfaces for STA and P2P GO in parallel, determines whether or not to change the P2P GO channel in response to receiving a CSA from AP101. For example, if STA and P2P GO are using the same DFS band frequency channel, the imaging device 102 changes the GO's frequency channel in response to the condition that the STA's frequency channel should be changed. At this time, the imaging device 102 controls the timing of the GO's frequency channel change so that the change of the GO's frequency channel is completed at the same time that the STA's frequency channel is changed. This prevents the imaging device 102 from entering a state where the GO is using a DFS band frequency channel during a period when the STA is not using a DFS band frequency channel. Furthermore, if STA and P2P GO are using different frequency channels or non-DFS band frequency channels, the imaging device 102 will only change the STA's frequency channel in response to receiving a CSA from AP101. In other words, the imaging device 102 may choose not to change the GO's frequency channel in such cases. This prevents unnecessary channel changes and helps prevent a decrease in communication efficiency in GO.

[0040] <Processing Example 2> When the imaging device 102 receives a CSA at an STA using the same DFS band frequency channel as the GO, it is assumed that the changed frequency channel of the STA, specified by the New Channel Number of the CSA, is in the DFS band. In this case, the imaging device 102 can set the frequency channel of the GO to the same channel as the STA. However, if a radar signal is detected on the changed DFS band channel, another channel change will be necessary. For this reason, the imaging device 102 may set the channel to use a non-DFS band frequency channel at the GO in such cases. In this processing example, an example of the processing flow in this case will be explained using Figures 7 and 8. Figure 7 is a diagram showing an example of the communication control flow in a wireless communication system, and Figure 8 is a diagram showing an example of the processing flow executed by the imaging device 102.

[0041] Steps S701-S705 in Figure 7 are the same as steps S501-S505 in Figure 5, and steps S801-S803 in Figure 8 are the same as steps S601-S603 in Figure 6, so their explanations are omitted. In this processing example, the imaging device 102 checks whether the changed channel of STA, indicated by the New Channel Number of the CSA Element confirmed in S704 or S801, is a DFS band channel (S706, S804). If the imaging device 102 confirms that the changed channel of STA is a DFS band channel (YES in S804), it sets the changed channel of GO to a non-DFS band frequency channel (S707, S809). In other words, in that case, the imaging device 102 changes the channel of GO to a channel different from the channel of STA. The imaging device 102 stores the value indicating the frequency channel set in S707 in New Channel Number, and generates a CSA Element that stores the Channel Switch Count set in S705. The imaging device 102 then transmits the generated wireless frame (Beacon frame, Probe Response frame, Action frame, etc.) containing the CSA Element to the information communication terminal 103 (S708, S806). The subsequent processing in S709-S712 and S807-S808 is the same as in S507-S510 in Figure 5 and S606-S607 in Figure 6, so the explanation is omitted. If the imaging device 102 confirms that the channel after the STA change is a non-DFS band channel (NO in S804), it may change the GO channel to the same channel as the channel after the STA change, similar to S604 in Figure 6 (S805). This is just one example, and the imaging device 102 may also change the GO channel to a different channel from the STA channel regardless of the destination when the STA channel is changed from a DFS band channel. The subsequent processing in S806-S808 is the same as in S605-S607 in Figure 6, so its explanation will be omitted.

[0042] As described above, this processing example prevents the GO's operating channel from changing from a DFS band frequency channel to another DFS band frequency channel. This prevents further channel changes due to the detection of a radar signal on the changed channel, thereby suppressing the decrease in efficiency caused by frequent channel changes. Furthermore, for example, if the STA's changed frequency channel is a DFS band channel, and the GO's frequency channel is moved to that channel first, there will be a period in which the GO uses a DFS band frequency channel different from the STA's operating channel. In other words, a frequency channel setting that is not permitted in WFD R2 may occur. For this reason, if the STA's changed frequency channel is a DFS band frequency channel and the GO uses the same channel as the STA, the GO needs to wait for the STA's frequency channel change to be completed before changing its channel. In contrast, this processing example changes the GO's frequency channel to a non-DFS band channel when the STA's changed frequency channel is a DFS band frequency channel. This makes it possible to change the GO's frequency channel without waiting for the STA's frequency channel change to be completed, preventing prolonged periods in which the GO cannot perform data communication, especially when the load on the GO is high.

[0043] <Processing Example 3> This processing example describes an example of the processing flow when the frequency channels before and after the STA change are both DFS band frequency channels, and GO uses the same channel as STA. In this processing example, it is assumed that the imaging device 102 has designated a DFS band channel as the frequency channel after the STA change based on the New Channel Number of the CSA received at STA, which is using the same DFS band frequency channel as GO. In this processing example, the processing when the imaging device 102 sets the frequency channel of GO to the same DFS band channel as STA will be explained using Figures 9 and 10. Figure 9 is a diagram showing an example of the communication control flow in a wireless communication system, and Figure 10 is a diagram showing an example of the processing flow executed by the imaging device 102.

[0044] Steps S901-S906 in Figure 9 are the same as steps S701-S706 in Figure 7, and steps S1001-S1004 in Figure 10 are the same as steps S801-S804 in Figure 8, so their explanations are omitted. If the imaging device 102 confirms that the frequency channel after the STA change is not a DFS band channel (it is a non-DFS band channel) (NO in S1004), it performs the same processing as steps S805-S808 in Figure 8 (S1005-S1008). As these processes are as described above, they will not be explained again here.

[0045] On the other hand, if the imaging device 102 confirms that the frequency channel after the STA change is a DFS band channel (YES in S1004), it starts processing to use that DFS band channel for GO as well. If the frequency channel after the GO change is a DFS band channel, the imaging device 102 must ensure that the GO channel is not changed before the frequency channel of STA is changed. Also, the imaging device 102 must not continue to use the previous DFS band channel for GO after the frequency channel of STA has been changed. For this reason, in this processing example, the imaging device 102 controls the second communication unit 305 by the control processing unit 301 to disconnect the connection with the information communication terminal 103 as GO and stop its function as GO (S907, S908, S1009). Then, the imaging device 102 controls the first communication unit 304 via the control processing unit 301 to change the channel used by STA to the channel indicated by the New Channel Number confirmed in S906 or S1001 (S910, S1010). Similarly, the channel used by AP101 is also changed (S909). The timing of the channel changes for the STA function of AP101 and imaging device 102 is the same as in the other processing examples described above.

[0046] Subsequently, the imaging device 102 restarts its GO function by controlling the second communication unit 305 via the control processing unit 301 and sets the GO's operating channel to use the same channel as the STA (S911, S1011). Then, the imaging device 102 connects to the P2P CL on the changed channel by controlling the second communication unit 305 via the control processing unit 301 (S912, S1012). The imaging device 102 may, for example, notify the information communication terminal 103 of information indicating the changed channel when disconnecting from the information communication terminal 103. Alternatively, the imaging device 102 may, for example, send information indicating the changed operating channel to the information communication terminal 103 in a Beacon frame or Probe Response frame after restarting the GO function.

[0047] As described above, in this processing example, the imaging device 102 temporarily stops its operation as a GO in order to change the channel used by the GO from a frequency channel in the DFS band to another frequency channel in the DFS band, and then restarts the GO on the changed channel after the STA's channel has been changed. This prevents the GO from being in a state where it is using a different DFS band channel than the one used by the STA. This makes it easier to manage the channels used by the imaging device 102. In particular, when it is acceptable for the GO's communication to be interrupted for a certain period of time, the imaging device 102 can efficiently manage the channels used without significantly reducing communication efficiency by having the GO and STA use the same frequency channel. As an example, the imaging device 102 may decide whether or not to allow the GO's frequency channel to be a DFS band channel depending on the size of the GO's communication load. Alternatively, the decision on whether or not to allow the GO's frequency channel to be a DFS band channel may be made based on other criteria.

[0048] Thus, according to this embodiment, a communication device such as an imaging device 102 that uses multiple communication interfaces capable of using DFS band frequency channels can appropriately set the channels to be used.

[0049] [Other embodiments] This disclosure can also be implemented by supplying a program that implements one or more of the functions of the above-described embodiments to a system or device via a network or storage medium, and by having one or more processors in the computer of that system or device read and execute the program. It can also be implemented by a circuit (e.g., an ASIC) that implements one or more functions.

[0050] (Summary of the embodiments) At least some of the embodiments described above can be summarized as follows: (Item 1) A communication device, A communication means capable of performing communication compliant with the IEEE 802.11 standard series using multiple communication interfaces, When a station (STA) is performing parallel communication with an access point (AP) using a first communication interface and communication with another device functioning as a Wi-Fi Direct (WFD) Group Owner (GO) using a second communication interface, and the first communication interface is using a frequency channel in a predetermined frequency band that requires support for Dynamic Frequency Selection (DFS), and a first wireless frame indicating a change in the frequency channel being used is received from the AP, a confirmation means for confirming whether the second communication interface is using the same frequency channel in the predetermined frequency band as the first communication interface, When it is confirmed that the second communication interface is using the same predetermined frequency band and frequency channel as the first communication interface, a modification means for changing the frequency channels of the first and second communication interfaces based on the first wireless frame, A communication device characterized by having the following features. (Item 2) The communication device according to item 1, characterized in that, if the modified frequency channel of the first communication interface is a frequency channel in a frequency band that does not require the DFS function to be supported, the frequency channel of the second communication interface is changed to the same frequency channel as the modified frequency channel of the first communication interface. (Item 3) The communication device according to item 1 or 2, characterized in that, if the modified frequency channel of the first communication interface is a frequency channel in a frequency band that requires the DFS function to be supported, the modification means changes the frequency channel of the second communication interface to a frequency channel in a frequency band that is different from the modified frequency channel of the first communication interface and does not require the DFS function to be supported. (Item 4) The communication device according to any one of items 1 to 3, characterized in that the modification means changes the frequency channel of the second communication interface before the timing of the change of the frequency channel of the first communication interface, which is specified by the first radio frame. (Item 5) The communication device according to any one of items 1 to 4, characterized in that the modification means is such that the other device, which functions as the CL, transmits to the other device a second radio frame containing information indicating the timing of the change of the frequency channel of the second communication interface and the frequency channel of the second communication interface after the change. (Item 6) The communication device according to item 5, characterized in that the second wireless frame is a Beacon frame, Probe Response frame, or Action frame containing a Channel Switch Announcement (CSA) Element. (Item 7) The communication device according to item 6, characterized in that the modification means changes the frequency channel of the second communication interface in response to the transmission of a Beacon frame as GO a predetermined number of times, and transmits the second wireless frame, in which the predetermined number of transmissions is stored as the Channel Switch Count value of the CSA Element, to the other device. (Item 8) The communication device according to item 6 or 7, characterized in that the modification means transmits the second radio frame, in which the modified frequency channel of the second radio frame is stored as the value of the New Channel Number of the CSA Element, to the other device. (Item 9) The communication device according to item 1, characterized in that the modification means, when the modified frequency channel of the first communication interface is a frequency channel in a frequency band that requires the DFS function to be supported, disconnects the connection with the other device that functions as the CL in the second communication interface and stops its function as GO, and after the frequency channel of the first communication interface is changed, restarts its function as GO using the same frequency channel as the modified frequency channel of the first communication interface and connects to the other device. (Item 10) The communication device according to any one of items 1 to 9, characterized in that the first wireless frame is a Beacon frame, a Probe Response frame, or an Action frame containing a Channel Switch Announcement (CSA) Element. (Item 11) The communication device according to item 10, characterized in that the modification means changes the frequency channel of the first communication interface after receiving the first wireless frame, in accordance with the elapsed period during which the AP has transmitted Beacon frames a number of times indicated by the Channel Switch Count value in the CSA Element of the first wireless frame. (Item 12) The communication device according to item 10 or 11, characterized in that the modification means changes the frequency channel of the first communication interface to a frequency channel identified by the value of the New Channel Number of the CSA Element of the first wireless frame. (Item 13) The communication device according to any one of items 1 to 12, characterized in that the modification means changes the frequency channel of the first communication interface and does not change the frequency channel of the second communication interface based on the first wireless frame when it is confirmed that the second communication interface is using a different frequency channel than the first communication interface, or when it is confirmed that the second communication interface is using the same frequency channel as the first communication interface but in a different frequency band than the predetermined frequency band. (Item 14) A control method performed by a communication device capable of performing communication compliant with the IEEE 802.11 standard series using multiple communication interfaces, When a station (STA) is performing parallel communication with an access point (AP) using a first communication interface, and communication with another device functioning as a Wi-Fi Direct (WFD) Group Owner (GO) using a second communication interface, and while the first communication interface is using a frequency channel in a predetermined frequency band that requires support for Dynamic Frequency Selection (DFS), a first wireless frame indicating a change in the frequency channel being used is received from the AP, it is confirmed whether the second communication interface is using the same frequency channel in the predetermined frequency band as the first communication interface, When it is confirmed that the second communication interface is using the same predetermined frequency band and frequency channel as the first communication interface, the frequency channels of the first and second communication interfaces are changed based on the first wireless frame. A control method characterized by including (Item 15) A program to cause a computer to function as one of the means of a communication device described in any one of items 1 through 13.

[0051] This disclosure is not limited to the embodiments described above, and various modifications and variations are possible without departing from the spirit and scope of this disclosure. [Explanation of symbols]

[0052] 101: AP, 102: Imaging device, 103: Information and communication terminal, 301: Control processing unit, 304: First communication unit, 305: Second communication unit, 306: CSA Element generation unit, 307: Channel usage confirmation unit

Claims

1. A communication device, A communication means capable of performing communication compliant with the IEEE 802.11 standard series using multiple communication interfaces, When a station (STA) is performing parallel communication with an access point (AP) using a first communication interface, and communication with another device functioning as a Wi-Fi Direct (WFD) Group Owner (GO) using a second communication interface, and the first communication interface is using a frequency channel in a predetermined frequency band that requires support for Dynamic Frequency Selection (DFS), and a first wireless frame indicating a change in the frequency channel being used is received from the AP, a confirmation means for confirming whether the second communication interface is using the same frequency channel in the predetermined frequency band as the first communication interface, When it is confirmed that the second communication interface is using the same predetermined frequency band and frequency channel as the first communication interface, a modification means for changing the frequency channels of the first and second communication interfaces based on the first wireless frame, A communication device characterized by having the following features.

2. The communication device according to claim 1, characterized in that, if the modified frequency channel of the first communication interface is a frequency channel in a frequency band that does not require the DFS function to be supported, the frequency channel of the second communication interface is changed to the same frequency channel as the modified frequency channel of the first communication interface.

3. The communication device according to claim 1, characterized in that, if the modified frequency channel of the first communication interface is a frequency channel in a frequency band that requires the DFS function to be supported, the modification means changes the frequency channel of the second communication interface to a frequency channel in a frequency band that is different from the modified frequency channel of the first communication interface and does not require the DFS function to be supported.

4. The communication device according to claim 1, characterized in that the modification means changes the frequency channel of the second communication interface before the timing of the change of the frequency channel of the first communication interface, which is specified by the first radio frame.

5. The communication device according to claim 1, characterized in that the modification means is such that the other device, which functions as the CL, transmits to the other device a second radio frame containing information indicating the timing of the change of the frequency channel of the second communication interface and the frequency channel of the second communication interface after the change.

6. The communication device according to claim 5, characterized in that the second wireless frame is a Beacon frame, a Probe Response frame, or an Action frame containing a Channel Switch Announcement (CSA) Element.

7. The communication device according to claim 6, characterized in that the modification means changes the frequency channel of the second communication interface in response to the transmission of a Beacon frame as GO a predetermined number of times, and transmits the second wireless frame, in which the predetermined number of transmissions is stored as the value of the Channel Switch Count of the CSA Element, to the other device.

8. The communication device according to claim 6, characterized in that the modification means transmits the second wireless frame, in which the modified frequency channel of the second wireless frame is stored as the value of the New Channel Number of the CSA Element, to the other device.

9. The communication device according to claim 1, characterized in that, if the modified frequency channel of the first communication interface is a frequency channel in a frequency band that requires the DFS function to be supported, the modification means disconnects the connection with the other device that functions as the CL in the second communication interface to stop its function as GO, and after the frequency channel of the first communication interface is changed, it restarts its function as GO using the same frequency channel as the modified frequency channel of the first communication interface and connects to the other device.

10. The communication device according to claim 1, characterized in that the first wireless frame is a Beacon frame, a Probe Response frame, or an Action frame containing a Channel Switch Announcement (CSA) Element.

11. The communication device according to claim 10, characterized in that the modifying means changes the frequency channel of the first communication interface after receiving the first wireless frame, in accordance with the elapsed period during which the AP has transmitted Beacon frames a number of times indicated by the Channel Switch Count value in the CSA Element of the first wireless frame.

12. The communication device according to claim 10, characterized in that the modification means changes the frequency channel of the first communication interface to a frequency channel identified by the value of the New Channel Number of the CSA Element of the first wireless frame.

13. The communication device according to claim 1, characterized in that the modification means, when it is confirmed that the second communication interface is using a different frequency channel than the first communication interface, or when it is confirmed that the second communication interface is using the same frequency channel as the first communication interface but in a different frequency band than the predetermined frequency band, modifies the frequency channel of the first communication interface and does not modify the frequency channel of the second communication interface based on the first wireless frame.

14. A control method performed by a communication device capable of performing communication compliant with the IEEE 802.11 standard series using multiple communication interfaces, When a station (STA) is performing parallel communication with an access point (AP) using a first communication interface, and communication with another device functioning as a Wi-Fi Direct (WFD) Group Owner (GO) using a second communication interface, and while the first communication interface is using a frequency channel in a predetermined frequency band that requires support for Dynamic Frequency Selection (DFS), if a first wireless frame indicating a change in the frequency channel being used is received from the AP, it is confirmed whether the second communication interface is using the same frequency channel in the predetermined frequency band as the first communication interface. When it is confirmed that the second communication interface is using the same predetermined frequency band and frequency channel as the first communication interface, the frequency channels of the first and second communication interfaces are changed based on the first wireless frame. A control method characterized by including

15. A program for causing a computer to function as one of the means of a communication device according to any one of claims 1 to 13.

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