JP7206692B2 - Communication device and computer program for communication device - Google Patents

Description

This specification discloses a technology related to a communication device that establishes a wireless connection with an access point.

Patent Document 1 discloses an access point that can use a DFS (abbreviation for Dynamic Frequency Selection) channel. At startup, the access point uses the DFS channel to perform CAC (abbreviation of Channel Availability Check) for 60 seconds to monitor whether radar is received using the DFS channel. Running CAC for 60 seconds is mandated by the standard. An access point transmits a beacon if it does not receive radar at its CAC. The client performs passive scanning of DFS channels by waiting for beacons transmitted from access points while sequentially switching channels.

Japanese Patent Application Laid-Open No. 2017-63408 JP 2017-153813 A JP 2017-143940 A

IEEE Standards 802.11h 2003

For example, according to the DFS standard, an access point stops using a DFS channel when detecting radar using the DFS channel after establishing a wireless connection with a client using the DFS channel. Then, the access point switches to a channel different from the channel whose use has been stopped. The above document does not disclose anything about the access point stopping the use of the channel and switching to a different channel. SUMMARY Techniques are provided herein for establishing a wireless connection to account for situations in which the target access point switches to a different channel.

The communication device disclosed in this specification uses a wireless interface capable of using N (N is an integer of 2 or more) channels, and a first channel of the N channels, a first establishing unit for establishing a first wireless connection with a target access point via an interface; and a switching signal from the target access point via the wireless interface after the first wireless connection is established. is received, the switching signal is a signal for notifying the communication device to switch from the first channel to a different channel and the first determination process uses at least some of the N channels according to a first rule to receive a specific signal from the target access point via the wireless interface. and the specific signal is not received from the target access point even if the first determination process is repeatedly executed over a predetermined period of time. a second determination process executing unit for executing a second determination process when it is not determined that the N number of channels are at least a part of the first channel; Execution of the second determination process, which is a process of determining whether or not the specific signal has been received from the target access point via the wireless interface, using a second rule different from the rule of and, in the first determination process or the second determination process, using a second channel different from the first channel out of the N channels, from the target access point to the specified a second establishing unit that establishes a second wireless connection with the target access point via the wireless interface using the second channel when it is determined that a signal has been received. .

For example, a comparative example is assumed in which only the first determination process is performed when a switching signal is received from the target access point. In this comparative example, the situation in which the specific signal was not received in the first rule of the first determination process cannot be considered. On the other hand, according to the above configuration, if the communication device does not receive the specific signal from the target access point even if the first determination process is repeatedly executed for a predetermined period of time, the first rule is A second determination process is executed according to a different second rule. For example, the target access point performs predetermined processing to switch to a different channel. The second rule may consider the situation in which the specific signal was not received from the target access point in the first rule due to the target access point performing a predetermined process. According to the above configuration, the wireless connection can be established considering the situation where the target access point switches to a different channel.

A computer program for implementing the above communication device and a computer-readable recording medium storing the computer program are also novel and useful. The method performed by the communication device described above is also novel and useful.

1 shows the configuration of a communication system; 4 shows a flowchart of a switching process. 4 shows a flow chart of connection processing of the first embodiment and the second embodiment. FIG. 4 shows a sequence diagram of a specific case of connection processing in the first embodiment; FIG. 10 is a sequence diagram of a specific case of connection processing in the second embodiment; FIG. FIG. 12 shows a flow chart of connection processing in the third embodiment and the fourth embodiment; FIG. FIG. 12 is a sequence diagram of a specific case of connection processing in the third embodiment; FIG. FIG. 12 is a sequence diagram of a specific case of connection processing in the fourth embodiment; FIG. 15 shows a flowchart of connection processing of the fifth embodiment. FIG. FIG. 12 is a sequence diagram of a specific case of connection processing in the fifth embodiment;

(Configuration of communication system 2; Fig. 1)
As shown in FIG. 1, the communication system 2 includes a printer 10, an access point 100, and a terminal device 500. Each device 10, 100, 500 is capable of wireless communication according to the Wi-Fi system. In addition, below, "access point" is described as "AP (abbreviation of Access Point)." The terminal device 500 is a desktop PC (abbreviation for Personal Computer), a notebook PC, a tablet PC, a mobile terminal, or the like.

(Configuration of AP100)
The AP 100 is a normal AP called a wireless AP, wireless LAN router, or the like. The AP 100 performs wireless communication according to the Wi-Fi system. The Wi-Fi system is, for example, IEEE (abbreviation of The Institute of Electrical and Electronics Engineers, Inc.) 802.11 standard and its equivalent standards (eg 802.11a, 11b, 11g, 11n, etc.). A wireless communication method for performing wireless communication. In particular, the AP 100 can execute processing related to DFS (an abbreviation for Dynamic Frequency Selection) defined by IEEE Standards 802.11h. This allows the AP 100 to use a carrier wave having a frequency of 5.0 GHz, particularly a carrier wave having the same frequency as those used for weather radar, military radar, and the like.

The 5.0 GHz frequency is classified into multiple frequency bands. Each frequency band is commonly referred to as a "channel." For example, frequencies from 5.150 GHz to 5.250 GHz are grouped into four channels, 36 to 48 channels. Hereinafter, "channel" may be described as "ch (abbreviation of Channel)". Further, frequencies from 5.250 GHz to 5.350 GHz are classified into four channels of 52ch to 64ch, and frequencies from 5.470 GHz to 5.725 GHz are classified into 11 channels of 100ch to 140ch. Here, 36ch to 48ch are called "W52", 52ch to 64ch are called "W53", and 100ch to 140ch are called "W56".

The frequency bands (or channels) classified as W53 and W56 include frequencies used for weather radar and the like. When using the W53 and W56 channels, the AP 100 executes CAC (abbreviation for Channel Availability Check) according to the DFS standard. In CAC, when a channel such as W53 is determined as a channel to be used, the AP 100 monitors for 60 seconds whether radar having a frequency included in the determined channel is detected. Then, when the radar is not detected for 60 seconds, the AP 100 broadcasts a beacon signal using the determined channel. As a result, while avoiding interference between the radar and the carrier wave, a channel such as W53 is used to establish a wireless LAN connection with the communication device (for example, the printer 10) that has received the beacon signal. It can participate in a wireless network formed by AP 100 . On the other hand, when the radar using the decided channel is detected, the AP 100 decides another channel as the channel to be used and executes CAC again.

The frequency band (or channel) classified as W52 is not used for weather radar or the like. Therefore, the AP 100 does not execute CAC when using the W52 channel. Hereinafter, the channels classified as W53 and W56 will be referred to as "DFS channels", and the channels classified as W52 will be referred to as "non-DFS channels".

Also, in a situation where the AP 100 establishes a wireless LAN connection using a certain DFS channel with a communication device, when detecting radar having the same frequency as the frequency included in the DFS channel being used, the DFS standard , stop using the DFS channel in use. Then, when stopping the use of the DFS channel in use, the AP 100 transmits a switching signal to the communication device and starts processing for switching to a channel different from the DFS channel in use. The switching signal is a signal for notifying the communication device to switch from the DFS channel in use to a different channel. Note that the switching signal is also transmitted when another AP using the same channel as the channel used by AP 100 exists in the vicinity of AP 100 . Specifically, the AP 100 sends the switching signal to the printer 10 when the number of beacon signals equal to or greater than the threshold is received by the AP 100 due to a plurality of other APs transmitting beacon signals. send and initiate the process to switch to a different channel. By switching to different channels, it is possible to avoid interference (that is, line congestion) between wireless communications performed by the AP 100 and wireless communications performed by other APs.

When the channel after switching is a DFS channel, the timing at which the beacon signal using the channel after switching is transmitted differs depending on the performance of the AP. The AP 100 of this embodiment is an AP that cannot perform wireless communication and CAC at the same time. Therefore, the AP 100 executes CAC after transmitting the switching signal. Then, the AP 100 performs processing for switching to a different channel after CAC and transmits a beacon signal. Therefore, the beacon signal is transmitted after at least 60 seconds have passed since the transmission of the switching signal. On the other hand, if the AP 100 is capable of performing wireless communication and CAC at the same time, the AP 100 can perform CAC using the switched channel before radar detection. Therefore, the AP 100 can transmit the beacon signal before 60 seconds have passed since the transmission of the switching signal.

The AP 100 also stores an SSID (abbreviation for Service Set Identifier) “XXX” for identifying the wireless network formed by the AP 100 .

(Configuration of printer 10)
The printer 10 is a peripheral device capable of executing a printing function (that is, a peripheral device such as the terminal device 500). The printer 10 has a wireless LAN interface 14 and a control section 20 . Each unit 14 to 20 is connected to a bus line (reference numerals omitted). Below, an interface is described as "I/F."

A wireless LAN I/F 14 is an I/F for performing wireless communication according to the Wi-Fi system. The wireless LAN I/F 14 can perform wireless communication using channels W52, W53, and W56. As shown in FIG. 1, the printer 10 establishes a wireless LAN connection with the AP 100 via the wireless LAN I/F 14 and participates in the wireless network formed by the AP 100 . Also, the terminal device 500 participates in the wireless network formed by the AP 100 . As a result, the printer 10 can receive print data from the terminal device 500 participating in the wireless network via the AP 100 and execute printing according to the print data.

The control unit 20 has a CPU 22 and a memory 24 . The CPU 22 executes various processes according to programs 30 stored in the memory 24 . The memory 24 is composed of a volatile memory, a nonvolatile memory, or the like. Memory 24 may also store AP information 34 . The AP information 34 includes an SSID (for example, SSID "XXX") for identifying the wireless network that the printer 10 is currently participating in, and a password for joining the wireless network.

(Switching process; Fig. 2)
The contents of the switching process executed by the CPU 22 of the printer 10 will be described with reference to FIG. The switching process is triggered by receiving a switching signal from an AP (for example, 100) when the printer 10 participates in a wireless network formed by the AP.

In S10, the CPU 22 uses the wireless LAN connection established with the AP 100 to determine whether print data is being received from the terminal device 500 via the AP 100. FIG. For example, the CPU 22 determines that print data is being received when part of the print data (for example, a packet) has been received from the AP 100 and the remaining part has not been received. When the CPU 22 determines that the print data is being received (YES in S10), in S12, the connection process (see FIG. 3) is executed. When S12 ends, the process of FIG. 2 ends.

When the CPU 22 determines that print data is not being received (NO in S10), the CPU 22 performs passive scanning using all available channels of the wireless LAN I/F 14 (that is, W52, W53, and W56) in ascending order. to start. First, in S20, the CPU determines 36ch of W52 among all the channels as the target channel. Next, in S24, the CPU 22 uses the target channel for a predetermined waiting time (for example, 100 msec) via the wireless LAN I/F 14 to determine whether a beacon signal has been received from the AP 100 or not. Specifically, when a beacon signal using the target channel is received and the CPU 22 determines that the SSID included in the beacon signal matches the SSID in the AP information 34, the CPU 22 uses the target channel from the AP 100. In other cases, it is determined that a beacon signal using the target channel has not been received from the AP 100 . When the beacon signal using the target channel is received from the AP 100 (YES in S24), the CPU 22 proceeds to S30.

In S30, CPU22 transmits the probe request containing SSID contained in the received beacon signal to AP100 via wireless LAN I/F14 using a target channel. When the CPU 22 receives a probe response to the probe request from the AP 100, the CPU 22 communicates with the AP 100 various signals (for example, an Authentication signal, an Association signal, a 4-way handshake, etc.) for establishing a wireless LAN connection. In the process of communicating the various signals described above, authentication using the password in the AP information 34 is performed between the AP 100 and the printer 10 . Thereby, the CPU 22 establishes wireless LAN connection with the AP 100 . When S30 ends, the process of FIG. 2 ends.

Further, when the beacon signal using the target channel is not received from the AP 100 (NO in S24), the CPU 22 determines in S26 whether a predetermined time (for example, 90 seconds) has elapsed since the switching signal was received. to judge whether If the CPU 22 determines that the predetermined time has not elapsed (NO in S26), it returns to S20 and changes the target channel from 36ch to 40ch. When returning to S20 without receiving a beacon signal from the AP 100 using any of all channels, the CPU 22 changes the target channel from 140ch to 36ch. That is, the CPU 22 repeatedly executes passive scanning using all channels (that is, W52, W53, and W56) in ascending order until the predetermined time elapses. When the CPU 22 determines that a predetermined time has elapsed without receiving a beacon signal from the AP 100 using any of all channels in repeated passive scans (YES in S26), the CPU 22 displays an error screen in S28. It is displayed on the display unit (not shown). The error screen indicates that a wireless LAN connection cannot be established with AP100. When S28 ends, the process of FIG. 2 ends.

In the modified example, when the target channel is determined from the four channels of W52 in S20, the CPU 22 executes active scanning instead of passive scanning, and selects four channels of W53 and W56. A passive scan may be performed to determine the target channel among the 11 channels. In active scanning, the CPU 22 broadcasts a probe request including the SSID in the AP information 34 using the target channel, and determines whether or not a probe response to the probe request has been received from the AP 100 . The CPU 22 determines YES in S24 when the probe response is received, and determines NO in S24 when the probe response is not received.

(Connection processing; Fig. 3)
The contents of the connection processing will be described with reference to FIG. S40 and S44 are the same as S20 and S24 in FIG. S46 is the same as S26 in FIG. 2, except that the predetermined time is 60 seconds. The above 60 seconds is determined as a time longer than or equal to 60 seconds during which CAC is executed. Alternatively, the predetermined time in S46 may be 60 seconds or more, for example 70 seconds.

The CPU 22 repeats the passive scan using all channels (that is, W52, W53, and W56) in ascending order for 60 seconds, but 60 seconds pass without receiving a beacon signal from the AP 100. If so (YES in S46), proceed to S50. At S50, the CPU 22 initiates a passive scan utilizing 15 DFS channels in ascending order, including channels W53 and W56. In S40, the 15 DFS channels are used in ascending order of 52ch, 56ch, 60ch, 64ch, 100ch, 104ch, . Also in S50, the 15 DFS channels are used in ascending order, as in S40.

S54 is similar to S44. S56 is the same as S46, except that the predetermined time is 90 seconds. That is, the CPU 22 repeatedly executes the passive scan using the 15 DFS channels in ascending order until 90 seconds have passed since the switching signal was received after the determination of YES in S46.

The CPU 22 determines that 90 seconds have passed since the switching signal was received without receiving the beacon signal from the AP 100 even though the passive scan using the 15 DFS channels in ascending order was repeatedly executed for 30 seconds. If so (YES in S56), proceed to S58. S58 is the same as S28 in FIG. When S58 ends, the process of FIG. 3 ends.

If the CPU 22 determines in either S44 or S54 that it has received a beacon signal from the AP 100 (YES in S44, YES in S54), it proceeds to S60. S60 is the same as S30 in FIG. When S60 ends, the process of FIG. 3 ends.

(Specific case; Figure 4)
A specific case realized by the connection processing in FIG. 3 will be described with reference to FIG. The printer 10 establishes a wireless LAN connection using 52ch with the AP 100 at T10. The terminal device 500 also establishes a wireless LAN connection with the AP 100 using 52ch. As a result, the printer 10 and the terminal device 500 join the wireless network formed by the AP 100 .

At T100, the printer 10 receives print data from the terminal device 500 via the AP100. Here, the AP 100 detects radar having the same frequency as the frequency included in 52ch while the print data received from the terminal device 500 is being sent to the printer 10 . In this case, the AP 100 transmits a switching signal to the printer 10 at T102, and then stops using 52ch. Thereby, the wireless LAN connection between the printer 10 and the AP 100 is disconnected. Note that the switching signal is also transmitted to the terminal device 500, and the wireless LAN connection between the terminal device 500 and the AP 100 is also disconnected.

At T104, the AP 100 determines 60ch of W53 (that is, the DFS channel) as the channel after switching, and starts CAC for using 60ch.

Further, when the printer 10 receives a switching signal from the AP 100 during reception of print data at T102, it determines that print data is being received (YES in S10 of FIG. 2), and starts connection processing (S12). .

As shown in FIG. 4, the printer 10 repeatedly performs passive scanning using W52, W53, and W56 in ascending order (S40 in FIG. 3). Note that FIG. 4 shows only the first passive scan, and omits the second and subsequent passive scans. Printer 10 does not receive a beacon signal from AP 100 at this time because AP 100 is executing CAC for using 60ch.

Since 60 seconds have passed since the printer 10 received the switching signal without receiving the beacon signal from the AP 100 (YES in S46 of FIG. 3), the printer 10 selects the 15 DFS channels (that is, W53 and W56) in ascending order. A passive scan to be used for scanning is started (S50 in FIG. 3). In the first and second passive scans, the AP 100 does not broadcast beacon signals. Since the printer 10 cannot receive the beacon signal from the AP 100 in the first and second passive scans, it performs the third passive scan.

While the second passive scan is being performed, the AP 100 starts broadcasting a beacon signal using 60ch at T106. Therefore, at T110, the printer 10 receives a beacon signal including the SSID "XXX" from the AP 100 during the use of 60ch in the third passive scan (YES in S54 of FIG. 3). At T120, the printer 10 establishes a wireless LAN connection using 60ch with the AP 100 (S60). After receiving the switching signal, the terminal device 500 performs scanning using W52, W53, and W56. The terminal device 500 establishes a wireless LAN connection with the AP 100 using 60ch when receiving a beacon signal using 60ch from the AP 100 .

When a wireless LAN connection using 60ch is established between the printer 10 and the AP 100 and between the terminal device 500 and the AP 100, the printer 10 again receives print data from the terminal device 500 via the AP 100. do. As a result, the printer 10 can execute printing according to the print data.

According to this case, when the switching signal is received after the 52ch wireless LAN connection is established (T102 in FIG. 4), the printer 10 switches all channels (that is, W52, W53, and W56) in ascending order. Repeatedly perform a passive scan that is used for Then, when 60 seconds have elapsed since receiving the switching signal without receiving a beacon signal from the AP 100, the printer 10 uses 15 DFS channels instead of passive scanning using all channels in ascending order. Start a passive scan that uses ascending order. In a situation where no beacon signal is received from AP 100 even when passive scans using all channels in ascending order are repeatedly executed for 60 seconds, there is a high possibility that AP 100 is executing CAC. For example, a comparative example in which only passive scans using all channels in ascending order are repeatedly executed is assumed. In this comparative example, the printer 10 still scans the non-DFS channel W52 after 60 seconds. In contrast, in the present embodiment, printer 10 does not scan non-DFS channels after 60 seconds have passed, but scans DFS channels. Therefore, compared to the comparative example, the beacon signal can be received from the AP 100 earlier, and the wireless LAN connection with the AP 100 can be established earlier.

Further, according to the configuration of this embodiment, the printer 10 executes the connection process of S12 in FIG. If so, the processes of S20 to S30 are executed. That is, the printer 10 does not execute the processes of S46 to S54 when print data is not being received from the terminal device 500 . In situations where print data is not being received from the terminal device 500, there is little need to establish a wireless LAN connection with the AP 100 early. In a comparative example in which the process of S10 of FIG. 2 is not executed and only the process of S12 (that is, the connection process of FIG. 3) is executed, wireless LAN connection can be quickly established even when print data is not being received. Although it can be done, the load on the CPU 22 that executes the processes of S46 to S54 increases. According to the configuration of this embodiment, it is possible to reduce the load on the CPU 22 in consideration of the situation in which print data is not being received, as compared with the comparative example.

(correspondence relationship)
The printer 10 and AP 100 are examples of the "communication device" and the "target access point", respectively. The wireless LAN I/F 14 is an example of a "wireless interface". Channels W52, W53, and W56 are examples of "N channels." 52ch and 60ch in FIG. 4 are examples of the "first channel" and the "second channel", respectively. A beacon signal is an example of a "specific signal." CAC and 60 seconds in S46 of FIG. 3 are examples of the "monitoring process" and the "predetermined time", respectively. The passive scan realized by the processes of S40 and S44 and the order of use in which W52, W53, and W56 are used in ascending order are examples of the "first determination process" and the "first rule," respectively. The passive scan realized by the processes of S50 and S54 and the order of use in which W53 and W56 are used in ascending order are examples of the "second determination process" and the "second rule", respectively.

T10 in FIG. 4, S40 to S44, S50 to S54, and S60 in FIG. It is an example of processing realized by the second establishing unit.

(Second embodiment)
(Connection processing; Fig. 3)
The second embodiment is the same as the first embodiment, except that the connection process is performed in step S52 instead of in step S50. The processing of S52 of this embodiment will be described with reference to FIG.

In S52, the CPU 22 starts a passive scan using each channel in order of W53, W56, W53, W56, and W52. Specifically, the CPU 22 uses the 11 channels of W56 in ascending order after using the 4 channels of W53 in ascending order. Next, the CPU 22 again uses the 4 channels of W53 in ascending order without using the channel of W52, and then again uses the 11 channels of W56 in ascending order. After using the 11 channels of W56 in ascending order, the CPU 22 uses the channels of W52 in ascending order. In other words, in S52, the DFS channels (i.e. W53, W56) are utilized before the non-DFS channels (i.e. W52), and the non-DFS channels are utilized after each of the DFS channels has been utilized twice. used. Passive scans that sequentially use each channel in the order of W53, W56, W53, W56, and W52 are repeatedly executed until 90 seconds elapse.

(Specific case; Figure 5)
A specific case realized by the connection processing (FIG. 3) of this embodiment will be described with reference to FIG. T20 and T200 to T204 are the same as T10 and T100 to T104 in FIG.

As shown in FIG. 5, upon receiving the switching signal from the AP 100 at T202, the printer 10 repeatedly executes passive scanning using W52, W53, and W56 in ascending order, as in FIG. S40). Since AP 100 is executing CAC for using 60ch, no beacon signal is received from AP 100 at this time.

Since 60 seconds have passed since the printer 10 received the switching signal without receiving the beacon signal from the AP 100 (YES in S46 of FIG. 3), the printer 10 selects each channel in order of W53, W56, W53, W56, and W52. The passive scan to be used is started (S52 in FIG. 3). In the first passive scan, the AP 100 does not broadcast beacon signals. Since the printer 10 cannot receive the beacon signal from the AP 100 in the first passive scan, it performs the second passive scan.

While the first passive scan is being performed, the AP 100 starts broadcasting a beacon signal using 60ch at T206. Therefore, at T210, the printer 10 receives a beacon signal including the SSID "XXX" from the AP 100 during use of 60ch in the second passive scan (YES in S54 of FIG. 3). T220 is the same as T120 in FIG.

According to this case, the printer 10 does not receive a beacon signal from the AP 100 in passive scanning using W52, W53, and W56 in ascending order, and when 60 seconds have passed since the switching signal was received, , instead of the passive scan described above, passive scans using the respective channels are started in order of W53, W56, W53, W56, and W52. For example, a comparative example in which only passive scans using W52, W53, and W56 in ascending order are repeatedly executed is assumed. In this comparative example, the printer 10 still utilizes the non-DFS channels before the DFS channels after 60 seconds. In contrast, in this embodiment, the printer 10 scans the DFS channels W53 and W56 before scanning the non-DFS channel W52. Therefore, compared to the comparative example, the beacon signal can be received from the AP 100 earlier, and the wireless LAN connection with the AP 100 can be established earlier.

Also, according to the above case, each of the DFS channels is utilized twice before each of the non-DFS channels is utilized. This makes it possible to increase the probability of early receiving a beacon signal from the AP 100 for which CAC has ended.

(correspondence relationship)
Passive scanning realized by S52 and S54 in FIG. An example.

(Third embodiment)
This embodiment is the same as the first embodiment except that the number table 32 is stored in the memory 24 of the printer 10 and the content of the connection process is different. The number table 32 is a table that associates and stores the channel number indicating the channel and the number information for each of the four channels of W53 and the eleven channels of W56 (see FIG. 1). Note that the description of the 11 channels of W56 is omitted in FIG. The number information indicates the number of other beacon signals that have been received when another beacon signal including an SSID different from the SSID “XXX” in the AP information 34 is received. Each piece of number information in the number table 32 is reset to "0" when the switching process in FIG. 2 ends.

(Connection processing; Fig. 6)
The connection processing of this embodiment will be described with reference to FIG. S70 and S74 are the same as S40 and S44 in FIG. When a beacon signal using the target channel is not received from AP 100 (NO in S74), CPU 22 determines in S76 whether a beacon signal has been received from an AP different from AP 100 using the target channel. to decide. In the process of S74, when one or more beacon signals are received, the CPU 22 determines that one or more received beacon signals include an SSID that does not match the SSID "XXX" in the AP information 34. exists, it is determined that a beacon signal has been received from a different AP. On the other hand, if no beacon signal is received in S76, the CPU 22 determines that no beacon signal has been received from a different AP. If the CPU 22 determines that a beacon signal has not been received from a different AP using the target channel (NO in S76), the CPU 22 skips S78 and S80 and proceeds to S86. On the other hand, when the CPU 22 determines that a beacon signal has been received from a different AP using the target channel (YES in S76), the process proceeds to S78.

In S78, the CPU 22 determines whether or not the target channel is the DFS channel (that is, W53, W56). When the CPU 22 determines that the target channel is not a DFS channel (NO in S78), the CPU 22 skips S80 and proceeds to S86. On the other hand, when the CPU 22 determines that the target channel is the DFS channel (YES in S78), the process proceeds to S80.

In S<b>80 , the CPU 22 identifies number information corresponding to the target channel from the number table 32 . Then, when the number of one or more beacon signals received in S76 is greater than the specified number information, the CPU 22 associates the target channel with number information indicating the number of one or more beacon signals. Stored in the number table 32 . On the other hand, if the number of one or more beacon signals received in S76 is equal to or less than the specified number information, the number information indicating the number of one or more beacon signals is not stored in the number table 32 . That is, the CPU 22 stores the number information indicating the maximum number in the number table 32 in repeated passive scans. In the modified example, when determining that a beacon signal has been received from a different AP using the target channel (YES in S76), the CPU 22 always stores the number information indicating the number of one or more beacon signals in the number table. 32 may be stored. That is, the CPU 22 may store the number information indicating the latest number in the number table 32 in repeated passive scans.

S86 is the same as S46 in FIG. When the CPU 22 determines that a predetermined time (for example, 60 seconds) has elapsed without receiving a beacon signal from the AP 100 using any of all channels in repeated passive scans (YES in S86), Proceed to S90.

In S90, the CPU 22 uses the number information in the number table 32 to determine the order of use of the 15 DFS channels including channels W53 and W56, and starts passive scanning to sequentially use the 15 DFS channels. do. Specifically, the CPU 22 arranges the four channels of W53 such that the channel corresponding to the number information indicating the number of 1 or more is in order from the channel corresponding to the number information indicating the number 0. Determine the order of use of the four channels of W53. For example, when the number information corresponding to 60ch indicates 1 and the number information corresponding to other channels indicates 0, the CPU 22 determines the order of use such as 60ch, 52ch, 56ch, and 64ch. The order of channels other than 60ch is ascending order as described above. Further, the CPU 22 determines the order of use of the 11 channels of W56 as well as the 4 channels of W53. Then, the CPU 22 combines the order of use of W53 and the order of use of W56 to determine the order of use of the 15 DFS channels. The CPU 22 sequentially determines target channels according to the determined order of use.

Further, the CPU 22 sets the waiting time of the channel corresponding to the number information indicating 0 to 100 msec, and sets the waiting time of the channel corresponding to the number information indicating the number of 1 or more to 200 msec. In other words, the CPU 22 makes the waiting time of the channel corresponding to the number information indicating one or more longer than the waiting time of the channel corresponding to the number information indicating zero. The standby time is the time to wait for reception of the beacon signal using the target channel.

S94 to S98 are the same as S54 to S58 in FIG. That is, the passive scan using the channels according to the order of use and waiting time determined in S90 is repeatedly executed until 90 seconds have passed.

If the CPU 22 determines in either S74 or S94 that it has received a beacon signal from the AP 100 (YES in S74, YES in S94), it proceeds to S100. S100 is the same as S30 in FIG. When S100 or S98 ends, the process of FIG. 6 ends.

(Specific case; Figure 7)
A specific case realized by the connection processing (FIG. 6) of this embodiment will be described with reference to FIG. T30, T300 to T304 are the same as T10, T100 to T104 in FIG.

As shown in FIG. 7, upon receiving the switching signal from the AP 100 at T302, the printer 10 repeatedly executes passive scanning using W52, W53, and W56 in ascending order as in FIG. S70). Since AP 100 is executing CAC for using 60ch, no beacon signal is received from AP 100 at this time.

In this case, an AP 200 different from the AP 100 exists around the printer 10 . The AP 200 broadcasts a beacon signal using 60ch. Therefore, the printer 10 receives a beacon signal using 60ch from the AP 200 at T305 (YES in S76 of FIG. 6). Since 60ch is a DFS channel (YES in S78), the printer 10 stores number information indicating one in the number table 32 in association with 60ch (S80). In this case, one is the maximum number.

Since 60 seconds have passed since the printer 10 received the switching signal without receiving the beacon signal from the AP 100 (YES in S86 of FIG. 6), the printer 10 uses the number information in the number table 32 to select 15 DFS channel utilization order is determined (S90 in FIG. 6). In this case, since the number information corresponding to 60ch indicates 1, the order of use of the four channels of 53 is determined as 60ch, 52ch, 56ch, and 64ch, the waiting time of 60ch is determined as 200 msec, 52ch, 56ch and 64ch times are determined to be 100 msec. Then, the printer 10 starts passive scanning using channels according to the determined order of use and waiting time (S90).

While the first passive scan is being performed, the AP 100 starts broadcasting a beacon signal using 60ch at T306. Therefore, at T310, the printer 10 receives a beacon signal including the SSID "XXX" from the AP 100 during the use of 60ch in the second passive scan (YES in S94 of FIG. 3). At T320, the printer 10 establishes a wireless LAN connection using 60ch with the AP 100 (S100).

According to this case, when a beacon signal using 60ch is received from a different AP 200 in passive scanning using W52, W53, and W56 in ascending order, the printer 10, instead of passive scanning, A passive scan is started according to the order of use in which 60ch is used before other channels (eg, 56ch). In a situation where different APs 200 are performing broadcast transmission of beacon signals using 60ch, CAC is less likely to detect radar using the frequency included in 60ch. That is, there is a high possibility that the AP 100 will determine 60ch as the post-switching channel and start transmitting beacon signals using 60ch after executing CAC. For example, in a comparative example in which only passive scans using W52, W53, and W56 are repeatedly executed in ascending order, the printer 10 continues to perform the other channels (for example, 52ch, 56ch) more than 60ch even after 60 seconds have passed. is also used first. In contrast, in this embodiment, 60ch, which has a high probability of receiving a beacon signal, is used before other channels. Therefore, compared to the comparative example, the beacon signal can be received from the AP 100 earlier, and the wireless LAN connection with the AP 100 can be established earlier.

Also, according to the above case, the waiting time of 60ch is longer than the waiting time of other channels. This makes it possible to increase the probability of early receiving a beacon signal from the AP 100 for which CAC has ended.

(correspondence relationship)
The passive scan realized by S90 and S94 in FIG. 6, and the order of use and the waiting time determined by using the number information in the number table 32 in S90 are the "second determination process" and the "second determination process," respectively. It is an example of "rules". In the specific case of FIG. 7, 56ch and 60ch are examples of "third channel" and "fourth channel", respectively.

(Fourth embodiment)
(Connection processing; Fig. 6)
The fourth embodiment is the same as the third embodiment except that the contents of S90 of the connection process are different. The processing of S90 of this embodiment will be described with reference to FIG.

In S90, the CPU 22 uses the channel corresponding to the number information indicating 1 or 2, the channel corresponding to the number information indicating 0, and the channel corresponding to the number information indicating 3 or more. , W53. For example, when the number information corresponding to 60ch indicates 1, the number information corresponding to 52ch and 64ch indicates 0, and the number information corresponding to 56ch indicates 3, 60ch, 52ch, and 64ch , 56ch determine the order of use. That is, the order of the channel corresponding to the number information indicating the number of 3 or more comes after the order of the other channels. Further, the CPU 22 determines the order of use of the 11 channels of W56 as well as the 4 channels of W53. Then, the CPU 22 combines the order of use of W53 and the order of use of W56 to determine the order of use of 15 channels including the channels of W53 and W56. The CPU 22 sequentially determines target channels according to the determined order of use. Further, the CPU 22 determines 100 msec for the waiting time of the channel corresponding to the number information indicating the number of 0 or 3 or more, and determines the waiting time for the channel corresponding to the number information indicating 1 or 2 to 200 msec. .

(Specific case; Figure 8)
A specific case realized by the connection processing (FIG. 6) of this embodiment will be described with reference to FIG. T40, T400 to T404 are the same as T10, T100 to T104 in FIG.

As shown in FIG. 8, upon receiving the switching signal from the AP 100 at T402, the printer 10 repeatedly executes passive scanning using W52, W53, and W56 in ascending order as in FIG. S70). Since AP 100 is executing CAC for using 60ch, no beacon signal is received from AP 100 at this time.

In this case, three APs 200, 300, and 400 different from the AP 100 exist around the printer 10. FIG. The three APs 200 to 400 broadcast beacon signals using 56ch. Therefore, at T405, the printer 10 receives three beacon signals using 56ch from three APs 200 to 400 (YES in S76 of FIG. 6). Since 56ch is a DFS channel (YES in S78), the printer 10 stores the number information indicating 3 in the number table 32 in association with 56ch (S80). In this case, the maximum number is three.

Since 60 seconds have passed since the printer 10 received the switching signal without receiving the beacon signal from the AP 100 (YES in S86 of FIG. 6), the printer 10 utilizes the number information in the number table 32 to perform W53 and W53. The order of use of 15 channels including the W56 channel is determined (S90 in FIG. 6). In this case, since the number information corresponding to 56ch indicates three, the order of use of the four channels of 53 is determined as 52ch, 60ch, 64ch, and 56ch, and the waiting time of each of the four channels is set to 100 msec. decide. Then, the printer 10 starts passive scanning using channels according to the determined order of use and waiting time (S90).

While the first passive scan is being performed, the AP 100 starts broadcasting a beacon signal using 60ch at T406. Therefore, at T410, the printer 10 receives a beacon signal including the SSID "XXX" from the AP 100 during the use of 60ch in the second passive scan (YES in S94 of FIG. 6). T420 is the same as T320 in FIG.

According to this case, the printer 10 receives three beacon signals using 56ch from three APs 200 to 400 in a passive scan using W52, W53, and W56 in ascending order. , passive scanning is started according to the order of use in which 56ch is used after other channels (eg, 60ch). In a situation where three APs 200 to 400 are performing broadcast transmission of beacon signals using 56ch, the line using 56ch is congested, and the AP 100 selects 56ch as the channel after switching. may determine different channels. That is, there is a high possibility that the AP 100 will decide a channel other than 56ch (for example, 60ch) as the channel after switching, and will start transmitting beacon signals using channels other than 56ch after executing CAC. For example, in a comparative example in which only passive scans using W52, W53, and W56 are repeatedly performed in ascending order, the printer 10 continues to perform 56ch before other channels (eg, 60ch) even after 60 seconds have elapsed. used for In contrast, in this embodiment, 56ch, which has a low probability of receiving a beacon signal, is used after other channels. Therefore, compared to the comparative example, the beacon signal can be received from the AP 100 earlier, and the wireless LAN connection with the AP 100 can be established earlier.

(correspondence relationship)
The passive scan realized by S90 and S94 in FIG. 6, and the order of use and the waiting time determined by using the number information in the number table 32 in S90 are the "second determination process" and the "second determination process," respectively. It is an example of "rules". In the specific case of FIG. 8, 56ch and 60ch are examples of "third channel" and "fourth channel", respectively.

(Fifth embodiment)
(Connection processing; Fig. 9)
This embodiment is the same as the first embodiment, except that the content of connection processing is different. The connection processing of this embodiment will be described with reference to FIG. S120 and S124 are the same as S40 and S44 in FIG. S126 is the same as S46 in FIG. 3, except that the predetermined time is 30 seconds. The 30 seconds above is determined as less than 60 seconds, which is the time during which CAC is performed. Alternatively, the predetermined time in S126 may be less than 60 seconds, for example 45 seconds.

Even if the CPU 22 repeats the passive scan using all channels (that is, W52, W53, and W56) in ascending order for 30 seconds, 30 seconds pass without receiving a beacon signal from the AP 100. If so (YES in S126), proceed to S130. At S130, the CPU 22 starts a passive scan using the four channels of W52 in ascending order. S134 is the same as S124, and S136 is the same as S126 except that the predetermined time is 60 seconds. That is, the CPU 22 repeatedly executes the passive scan using the four channels of W52 in ascending order until 60 seconds have elapsed since the switching signal was received after the determination of YES in S126.

Even if the CPU 22 repeats the passive scan using the four channels of W52 in ascending order for 30 seconds, the beacon signal is not received from the AP 100, and 60 seconds have passed since the switch signal was received. If so (YES in S136), the process proceeds to S140. S140 to S148 are the same as S50 to S158 in FIG.

If the CPU 22 determines in any of S124, S134, and S144 that it has received a beacon signal from the AP 100 (YES in S124, YES in S134, or YES in S144), it proceeds to S160. S160 is the same as S60 in FIG. When S148 or S160 ends, the process of FIG. 9 ends.

(Specific case; Fig. 10)
A specific case realized by the connection processing (FIG. 9) of this embodiment will be described with reference to FIG. T50, T500 and T502 are the same as T10, T100 and T102 in FIG. When the AP 100 transmits a switching signal to the printer 10 at T502, at T504 it starts processing for switching 52ch to one of the four channels of W52.

As shown in FIG. 10, upon receiving the switching signal from the AP 100 at T502, the printer 10 repeatedly executes passive scanning using W52, W53, and W56 in ascending order as in FIG. S120). The printer 10 does not receive a beacon signal from the AP 100 at this time because the AP 100 is executing processing for switching to W52.

Since 30 seconds have passed since the printer 10 received the switching signal without receiving the beacon signal from the AP 100 (YES in S126 of FIG. 9), the printer 10 performs passive scanning using the four channels of W52 in ascending order. Start (S130).

The processing for switching to W52 is completed while the first passive scan is being performed, 48ch is determined as the channel after switching, and the AP 100 starts broadcasting a beacon signal using 48ch in T506. . Therefore, at T510, the printer 10 receives a beacon signal including the SSID "XXX" from the AP 100 while using 48ch in the second passive scan (YES in S134 of FIG. 9). At T520, the printer 10 establishes a wireless LAN connection using 48ch with the AP 100 (S160).

According to this case, the printer 10 does not receive a beacon signal from the AP 100 in the passive scan using W52, W53, and W56 in ascending order. , instead of the passive scan described above, a passive scan using the four channels of W52 in ascending order is initiated. In a situation where a beacon signal is not received from AP 100 even when passive scans using all channels in ascending order are repeatedly executed for 30 seconds, there is a high possibility that AP 100 is executing some processing. For example, if the AP 100 is performing CAC, the AP 100 will start transmitting beacon signals after at least 60 seconds have elapsed since transmitting the switching signal. Also, for example, when the AP 100 is executing processing for switching to W52, the AP 100 starts transmitting the beacon signal before 60 seconds have passed since the transmission of the switching signal. In other words, it is unlikely that a beacon signal using the DFS channel will be transmitted during the time after 30 seconds have passed since the transmission of the switching signal and before 60 seconds have passed since the transmission of the switching signal. , a beacon signal may be transmitted using a non-DFS channel. For example, in a comparative example in which only passive scans using all channels in ascending order are repeatedly performed, the printer 10 continues to scan the DFS channels (ie, W53, W56) even after 30 seconds have passed. In contrast, in the present embodiment, the printer 10 does not scan the DFS channels after 30 seconds have passed, but scans the non-DFS channels (ie, W52). Therefore, when the AP 100 is executing processing for switching to W52, the beacon signal can be received from the AP 100 earlier than in the comparative example, and the wireless LAN connection with the AP 100 can be established earlier. can be done.

(correspondence relationship)
30 seconds in S126 of FIG. 9 is an example of the "predetermined time". The passive scan realized by S130 and S134 in FIG. 9 and the use order of using four channels in W52 in ascending order are examples of the "second determination process" and the "second rule", respectively.

(Reference example)
A reference example in which the fifth embodiment is modified will be described with reference to FIG. In this reference example, the processes of S130 and S134 are not executed. That is, the CPU 22 starts scanning at a time after 30 seconds have passed since the transmission of the switching signal and before 60 seconds have passed since the transmission of the switching signal (hereinafter referred to as "specific time"). don't run Then, when 60 seconds have passed since receiving the switching signal (YES in S136), the CPU 22 starts passive scanning using 15 DFS channels (that is, W53 and W56) in ascending order in S140. .

As noted above, it is unlikely that a beacon signal will be transmitted over a DFS channel at any given time. Further, for example, when the switching process for switching to the channel of W52 is executed, if the processing performance of the AP 100 is relatively high, the AP 100 transmits the beacon before 30 seconds have passed since the transmission of the switching signal. Likely to start sending signals. In this case, the AP 100 is less likely to transmit a beacon signal at a particular time. In this reference example, the processing load on the printer 10 can be reduced compared to a comparative example in which scanning is performed at a specific time.

The features of this reference example are described below. A communication device uses a wireless interface capable of using N channels (where N is an integer equal to or greater than 2), and a first channel among the N channels to transmit a target through the wireless interface a first establishing unit that establishes a first wireless connection with an access point; and when a switching signal is received from the target access point via the wireless interface after the first wireless connection is established. , a first determination process execution unit that executes a first determination process, wherein the switching signal is a signal for notifying the communication device that the channel is switched from the first channel to a different channel; is a process of sequentially using at least some of the N channels to determine whether or not a specific signal has been received from the target access point via the wireless interface. the first determination processing execution unit, and when it is not determined that the specific signal has been received from the target access point even when the first determination processing is repeatedly executed for a first predetermined time, the A second determination process executing unit that executes a second determination process when a second predetermined time has elapsed since the switching signal was received, wherein the second determination process is performed on the N channels. sequentially using at least some of the channels to determine whether or not the specific signal has been received from the target access point via the wireless interface, wherein the switching signal is received the determination process is not executed during the time after the first predetermined time has passed since the switching signal is received and before the second predetermined time has passed since the switching signal is received; and a processing execution unit, in the first determination processing or the second determination processing, using a second channel different from the first channel among the N channels, from the target access point a second establishing unit that establishes a second wireless connection with the target access point via the wireless interface using the second channel when it is determined that the specific signal has been received; Prepare. 30 seconds in S126 and 60 seconds in S136 in FIG. 9 are examples of the "first predetermined time period" and the "second predetermined time period", respectively. The passive scan realized by S120 and S124 in FIG. 9 and the passive scan realized by S140 and S144 of FIG. 9 are examples of the "first determination process" and the "second determination process", respectively.

Although specific examples of the present invention have been described in detail above, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above. Modifications of the above embodiment are listed below.

(Modification 1) The “communication device” may not be the printer 10, but may be a scanner, a multi-function device, a server, or a terminal device other than the terminal device 500, for example.

(Modification 2) The wireless LAN I/F 14 is not limited to wireless communication using channels W52, W53, and W56, and may be capable of wireless communication using a carrier wave having a frequency of 2.4 GHz. . In this modification, “N channels” may include channels (eg, 1ch to 14ch) for using carrier waves with a frequency of 2.4 GHz. Also, the wireless LAN I/F 14 may not be able to use any one of W52, W53, and W56. In this modification, for example, eight channels including channels W52 and W53 are an example of "N channels".

(Modification 3) In the first embodiment described above, the printer 10 starts passive scanning using W53 and W56 in ascending order in S50 of FIG. Alternatively, printer 10 uses all channels (i.e., W52, W53, and W56) in ascending order, with a wait time of 100 msec for each of W52 and a wait time of 100 msec for each of W53 and W56. A passive scan of 200 msec may be initiated. In this modified example, the rule of using all channels in ascending order and setting the standby time to 200 msec for each channel of W53 and W56 is an example of the "second rule."

(Modification 4) In the above-described second embodiment, the printer 10 starts passive scanning in S52 of FIG. 3, using each channel in ascending order of W53, W56, W53, W56, and W52. Alternatively, the printer 10 may initiate passive scanning using each channel in order of W53, W56, and W52. In this modification, the order of using each channel in the order of W53, W56, and W52 is an example of the "second rule."

(Variation 5) In the third embodiment described above, the printer 10 determines the order of use of W53 and the order of use of W56 using the number information in S90 of FIG. Then, the printer 10 starts passive scanning sequentially using 15 DFS channels including channels W53 and W56 according to a combination of the order of use of W53 and the order of use of W56. Alternatively, the printer 10 may start passive scanning that sequentially uses all channels according to a combination of the ascending order of use in W52, the determined order of use in W53, and the determined order of use in W56. Here, W52 may be used before W53 and W56, or may be used after W53 and W56. In this modified example, a combination of the ascending order of use of W52, the order of use of W53, and the order of use of W56 is an example of the "second rule".

(Modification 6) In S90 of FIG. 6, the printer 10 does not need to lengthen the standby time of the channel corresponding to the number information indicating the number of one or more. In this variation, the "second rule" may be a rule including using the third and fourth channels for the first time.

(Modification 7) In the above-described fourth embodiment, the printer 10, in S90 of FIG. The use order of the four channels of W53 is determined so that the channels corresponding to the number information indicating the number of W53 are used in order. Instead, the printer 10 uses the channels corresponding to the number information indicating the number of less than 3 in ascending order and then the channels corresponding to the number information indicating the number of 3 or more in order of W53. The order of utilization of the four channels may be determined. In this modification, the order of use is to use the channels corresponding to the number information indicating the number of less than 3 in ascending order, and then use the channels corresponding to the number information indicating the number of 3 or more in the order of use according to the "second rule." is an example of

(Modification 8) As described above, the printer 10 may perform active scanning when the target channel is determined from among the four channels of W52. The printer 10 may then determine whether or not a probe response to the probe request has been received from the AP 100 . In this modified example, the probe response is an example of the "specific signal".

(Modification 9) As described above, the "switching signal" is also transmitted when a plurality of APs using the same channel as the channel used by AP 100 exist around AP 100. . Then, the printer 10 may execute the process of FIG. 2 when the switching signal due to the above reason is received. In this modification, the "target access point" does not have to execute the "monitoring process".

(Modification 10) The process of S10 in FIG. 2 may not be executed. In this modified example, the "determination unit" can be omitted.

(Modification 11) In each of the embodiments described above, the CPU 22 of the printer 10 executes the program 30 (that is, software) to implement the processes shown in FIGS. Alternatively, any processing may be implemented by hardware such as logic circuits.
The features of the technology disclosed in this specification are listed below.
(Item 1)
A communication device,
a wireless interface capable of using N channels (where N is an integer equal to or greater than 2);
a first establishing unit that establishes a first wireless connection with a target access point via the wireless interface using a first channel among the N channels;
A first determination process execution unit that executes a first determination process when a switching signal is received from the target access point via the wireless interface after the first wireless connection is established. the switching signal is a signal for notifying the communication device to switch from the first channel to a different channel; according to a first rule to determine whether a specific signal has been received from the target access point via the wireless interface;
a second determination process executing unit for executing a second determination process when it is not determined that the specific signal has been received from the target access point even after the first determination process is repeatedly performed over a predetermined period of time; wherein the second determination process utilizes at least some of the N channels according to a second rule different from the first rule, via the wireless interface, the second determination process executing unit, which is a process of determining whether the specific signal has been received from the target access point;
In the first determination process or the second determination process, the specific signal is received from the target access point using a second channel different from the first channel among the N channels. a second establishing unit that establishes a second wireless connection with the target access point via the wireless interface using the second channel when it is determined that the
A communication device comprising:
(Item 2)
The target access point is
transmitting the switching signal to the communication device when radar is detected using the first channel after the first wireless connection is established;
When the different channel is a DFS (abbreviation of Dynamic Frequency Selection) channel, performing a monitoring process for monitoring whether or not radar is detected using the different channel,
The communication device according to item 1, wherein the predetermined time is longer than or equal to the time during which the monitoring process is executed.
(Item 3)
The N channels include a plurality of DFS (abbreviation for Dynamic Frequency Selection) channels and a plurality of non-DFS channels,
3. The communication device according to item 1 or 2, wherein the second rule is a rule including preferentially utilizing DFS channels over non-DFS channels compared to the first rule.
(Item 4)
the first rule includes sequentially utilizing each of the N channels including the plurality of DFS channels and the plurality of non-DFS channels;
The communication device according to item 3, wherein the second rule includes sequentially utilizing each of the plurality of channels including the plurality of DFS channels and not including the plurality of non-DFS channels. .
(Item 5)
the first rule is a rule including utilizing a third channel of the plurality of DFS channels before a fourth channel of the plurality of DFS channels;
In the first determination process, if the specific signal is received from an access point different from the target access point using the fourth channel, the second rule determines that the fourth channel is used. prior to the third channel.
(Item 6)
the first rule includes utilizing each of the plurality of DFS channels for a first time;
In the first determination process, if the specific signal is received from an access point different from the target access point using a fourth channel, the second rule uses the fourth channel. utilizing for a second time period longer than the first time period, and among the plurality of DFS channels, one or more channels different from the fourth channel are each used for the first time period; 6. The communication device according to any one of items 3 to 5, wherein the rules include using all over.
(Item 7)
the first rule is a rule including utilizing a third channel of the plurality of DFS channels before a fourth channel of the plurality of DFS channels;
In the first determination process, if the specific signal is received from a threshold number or more of access points different from the target access point using the third channel, the second rule is , a rule comprising utilizing the third channel after the fourth channel;
5. The communication device according to item 3 or 4, wherein the threshold is an integer of 2 or more.
(Item 8)
The communication device according to item 4, wherein the order of use of the plurality of DFS channels in the second rule is the same as the order of use of the plurality of DFS channels in the first rule.
(Item 9)
the first rule includes sequentially utilizing each of the N channels including the plurality of DFS channels and the plurality of non-DFS channels;
the second rule includes sequentially utilizing each of the N channels including the plurality of DFS channels and the plurality of non-DFS channels;
the first rule is a rule including utilizing the plurality of non-DFS channels before the plurality of DFS channels;
4. The communication device according to item 3, wherein the second rule is a rule including utilizing the plurality of DFS channels before the plurality of non-DFS channels.
(Item 10)
the first rule is a rule including utilizing the plurality of non-DFS channels before the plurality of DFS channels;
The second rule includes using each of the plurality of DFS channels without using the plurality of non-DFS channels after using each of the plurality of DFS channels once. The communication device according to item 9, wherein:
(Item 11)
The target access point is
transmitting the switching signal to the communication device when radar is detected using the first channel after the first wireless connection is established;
When the different channel is a DFS (abbreviation of Dynamic Frequency Selection) channel, performing a monitoring process for monitoring whether or not radar is detected using the different channel,
The predetermined time is a time less than the time during which the monitoring process is executed,
the N channels include a plurality of DFS channels and a plurality of non-DFS channels;
the first rule includes sequentially utilizing each of the N channels including the plurality of DFS channels and the plurality of non-DFS channels;
The communication device according to item 1, wherein the second rule includes sequentially using each of the plurality of channels that do not include the plurality of DFS channels and that include the plurality of non-DFS channels. .
(Item 12)
The target access point is
transmitting the switching signal to the communication device when radar is detected using the first channel after the first wireless connection is established;
When the different channel is a DFS (abbreviation of Dynamic Frequency Selection) channel, performing a monitoring process for monitoring whether or not radar is detected using the different channel,
In the first determination process and the second determination process,
Determining whether a beacon signal, which is the specific signal, has been received from the target access point when a DFS channel is used,
Items 1 to 11, wherein when a non-DFS channel is used, a probe request is transmitted to the target access point, and it is determined whether a probe response, which is the specific signal, is received from the target access point. A communication device according to any one of the preceding claims.
(Item 13)
The communication device further
a determination unit that determines whether communication using the first wireless connection is in progress when the switching signal is received from the target access point;
When it is determined that communication using the first wireless connection is in progress,
The first determination process executing unit executes the first determination process,
The second determination process execution unit performs the second determination when it is not determined that the specific signal is received from the target access point even after the first determination process is repeatedly executed over the predetermined time. perform the processing,
When it is determined that communication using the first wireless connection is not being executed,
The first determination process executing unit executes the first determination process,
12. The communication device according to any one of items 1 to 11, wherein the second determination process execution unit does not execute the second determination process.
(Item 14)
A computer program for a communication device, comprising:
The communication device
A wireless interface capable of using N (N is an integer of 2 or more) channels;
The computer of the communication device has the following parts:
a first establishing unit that establishes a first wireless connection with a target access point via the wireless interface using a first channel among the N channels;
A first determination process execution unit that executes a first determination process when a switching signal is received from the target access point via the wireless interface after the first wireless connection is established. the switching signal is a signal for notifying the communication device to switch from the first channel to a different channel; according to a first rule to determine whether a specific signal has been received from the target access point via the wireless interface;
a second determination process executing unit for executing a second determination process when it is not determined that the specific signal has been received from the target access point even after the first determination process is repeatedly performed over a predetermined period of time; wherein the second determination process utilizes at least some of the N channels according to a second rule different from the first rule, via the wireless interface, the second determination process executing unit, which is a process of determining whether the specific signal has been received from the target access point;
In the first determination process or the second determination process, the specific signal is received from the target access point using a second channel different from the first channel among the N channels. a second establishing unit that establishes a second wireless connection with the target access point via the wireless interface using the second channel when it is determined that the
A computer program that acts as

2: communication system, 10: printer, 14: wireless LAN I/F, 20: control unit, 22: CPU, 24: memory, 30: program, 32: number table, 34: AP information, 100: access point, 500: terminal equipment

Claims (14)

A communication device,
a wireless interface capable of using N (N is an integer equal to or greater than 2) channels including a plurality of DFS (abbreviation of Dynamic Frequency Selection) channels and a plurality of non-DFS channels ;
a first establishing unit that establishes a first wireless connection with a target access point via the wireless interface using a first channel among the N channels;
A first determination process execution unit that executes a first determination process when a switching signal is received from the target access point via the wireless interface after the first wireless connection is established. the switching signal is a signal for notifying the communication device to switch from the first channel to a different channel; according to a first rule to determine whether a specific signal has been received from the target access point via the wireless interface;
a second determination process executing unit for executing a second determination process when it is not determined that the specific signal has been received from the target access point even after the first determination process is repeatedly performed over a predetermined period of time; wherein the second determination process utilizes at least some of the N channels according to a second rule different from the first rule, via the wireless interface, It is a process of determining whether or not the specific signal has been received from the target access point, and the second rule preferentially uses DFS channels over non-DFS channels compared to the first rule. the second determination processing execution unit , which is a rule including :
In the first determination process or the second determination process, the specific signal is received from the target access point using a second channel different from the first channel among the N channels. a second establishing unit that establishes a second wireless connection with the target access point via the wireless interface using the second channel when it is determined that the
A communication device comprising: The target access point is
transmitting the switching signal to the communication device when radar is detected using the first channel after the first wireless connection is established;
When the different channel is a DFS (abbreviation of Dynamic Frequency Selection) channel, performing a monitoring process for monitoring whether or not radar is detected using the different channel,
2. The communication device according to claim 1, wherein said predetermined time is a time equal to or longer than the time during which said monitoring process is executed. the first rule includes sequentially utilizing each of the N channels including the plurality of DFS channels and the plurality of non-DFS channels;
3. A rule according to claim 1 or 2 , wherein said second rule comprises sequentially utilizing each of a plurality of channels including said plurality of DFS channels and not including said plurality of non-DFS channels. communication equipment. the first rule is a rule including utilizing a third channel of the plurality of DFS channels before a fourth channel of the plurality of DFS channels;
In the first determination process, if the specific signal is received from an access point different from the target access point using the fourth channel, the second rule determines that the fourth channel is used. prior to the third channel. the first rule includes utilizing each of the plurality of DFS channels for a first time;
In the first determination process, if the specific signal is received from an access point different from the target access point using a fourth channel, the second rule uses the fourth channel. utilizing for a second time period longer than the first time period, and among the plurality of DFS channels, one or more channels different from the fourth channel are each used for the first time period; 5. A communication device according to any one of claims 1 to 4 , wherein the rule is a rule comprising using over a period of time. the first rule is a rule including utilizing a third channel of the plurality of DFS channels before a fourth channel of the plurality of DFS channels;
In the first determination process, if the specific signal is received from a threshold number or more of access points different from the target access point using the third channel, the second rule is , a rule comprising utilizing the third channel after the fourth channel;
The communication device according to any one of claims 1 to 3 , wherein said threshold is an integer of 2 or more. 4. The communication device according to claim 3 , wherein the order of use of said plurality of DFS channels in said second rule is the same as the order of use of said plurality of DFS channels in said first rule. the first rule includes sequentially utilizing each of the N channels including the plurality of DFS channels and the plurality of non-DFS channels;
the second rule includes sequentially utilizing each of the N channels including the plurality of DFS channels and the plurality of non-DFS channels;
the first rule is a rule including utilizing the plurality of non-DFS channels before the plurality of DFS channels;
3. The communication device according to claim 1 or 2 , wherein said second rule is a rule including utilizing said plurality of DFS channels before said plurality of non-DFS channels. the first rule is a rule including utilizing the plurality of non-DFS channels before the plurality of DFS channels;
The second rule includes using each of the plurality of DFS channels without using the plurality of non-DFS channels after using each of the plurality of DFS channels once. 9. The communication device according to claim 8 , wherein: A communication device,
a wireless interface capable of using N channels (where N is an integer equal to or greater than 2) including a plurality of DFS channels and a plurality of non-DFS channels ;
a first establishing unit that establishes a first wireless connection with a target access point via the wireless interface using a first channel among the N channels;
A first determination process execution unit that executes a first determination process when a switching signal is received from the target access point via the wireless interface after the first wireless connection is established. the switching signal is a signal for notifying the communication device to switch from the first channel to a different channel; according to a first rule to determine whether a specific signal has been received from the target access point via the wireless interface;
the first rule includes sequentially utilizing each of the N channels including the plurality of DFS channels and the plurality of non-DFS channels;
The target access point is
transmitting the switching signal to the communication device when radar is detected using the first channel after the first wireless connection is established;
When the different channel is a DFS (abbreviation of Dynamic Frequency Selection) channel, perform a monitoring process for monitoring whether or not radar is detected using the different channel;
the first determination processing execution unit;
If it is not determined that the specific signal has been received from the target access point even if the first determination process is repeatedly performed over a predetermined time period that is less than the time period during which the monitoring process is performed, a second determination process is performed. A second determination process execution unit that executes a determination process, wherein the second determination process determines at least some of the N channels according to a second rule different from the first rule. determining whether the specific signal has been received from the target access point via the wireless interface using according to, wherein the second rule includes the plurality of DFS channels. the second decision processing execution unit , which is a rule including sequentially utilizing each of a plurality of channels including the plurality of non-DFS channels and the plurality of non-DFS channels ;
In the first determination process or the second determination process, the specific signal is received from the target access point using a second channel different from the first channel among the N channels. a second establishing unit that establishes a second wireless connection with the target access point via the wireless interface using the second channel when it is determined that the
A communication device comprising: The target access point is
transmitting the switching signal to the communication device when radar is detected using the first channel after the first wireless connection is established;
When the different channel is a DFS (abbreviation of Dynamic Frequency Selection) channel, performing a monitoring process for monitoring whether or not radar is detected using the different channel,
In the first determination process and the second determination process,
determining whether a beacon signal, which is the specific signal, is received from the target access point when a DFS channel is used ;
11. When a non - DFS channel is used, it is determined whether a probe request is transmitted to the target access point and a probe response, which is the specific signal, is received from the target access point. The communication device according to any one of Claims 1 to 3. The communication device further
a determination unit that determines whether communication using the first wireless connection is in progress when the switching signal is received from the target access point;
When it is determined that communication using the first wireless connection is in progress,
The first determination process executing unit executes the first determination process,
The second determination process execution unit performs the second determination when it is not determined that the specific signal is received from the target access point even after the first determination process is repeatedly executed over the predetermined time. perform the processing,
When it is determined that communication using the first wireless connection is not being executed,
The first determination process executing unit executes the first determination process,
The communication device according to any one of claims 1 to 10 , wherein said second determination process execution unit does not execute said second determination process. A computer program for a communication device, comprising:
The communication device
a plurality of DFS (abbreviation of Dynamic Frequency Selection) channels and a plurality of non-DFS channels ;
The computer of the communication device has the following parts:
a first establishing unit that establishes a first wireless connection with a target access point via the wireless interface using a first channel among the N channels;
A first determination process execution unit that executes a first determination process when a switching signal is received from the target access point via the wireless interface after the first wireless connection is established. the switching signal is a signal for notifying the communication device to switch from the first channel to a different channel; according to a first rule to determine whether a specific signal has been received from the target access point via the wireless interface;
a second determination process executing unit for executing a second determination process when it is not determined that the specific signal has been received from the target access point even after the first determination process is repeatedly performed over a predetermined period of time; wherein the second determination process utilizes at least some of the N channels according to a second rule different from the first rule, via the wireless interface, It is a process of determining whether or not the specific signal has been received from the target access point, and the second rule preferentially uses DFS channels over non-DFS channels compared to the first rule. the second determination processing execution unit , which is a rule including :
In the first determination process or the second determination process, the specific signal is received from the target access point using a second channel different from the first channel among the N channels. a second establishing unit that establishes a second wireless connection with the target access point via the wireless interface using the second channel when it is determined that the
A computer program that acts as A computer program for a communication device, comprising:
The communication device
A wireless interface capable of using N (N is an integer equal to or greater than 2) channels including a plurality of DFS channels and a plurality of non-DFS channels ;
The computer of the communication device has the following parts:
a first establishing unit that establishes a first wireless connection with a target access point via the wireless interface using a first channel among the N channels;
A first determination process execution unit that executes a first determination process when a switching signal is received from the target access point via the wireless interface after the first wireless connection is established. the switching signal is a signal for notifying the communication device to switch from the first channel to a different channel; according to a first rule to determine whether a specific signal has been received from the target access point via the wireless interface;
the first rule includes sequentially utilizing each of the N channels including the plurality of DFS channels and the plurality of non-DFS channels;
The target access point is
transmitting the switching signal to the communication device when radar is detected using the first channel after the first wireless connection is established;
When the different channel is a DFS (abbreviation of Dynamic Frequency Selection) channel, perform a monitoring process for monitoring whether or not radar is detected using the different channel;
the first determination processing execution unit;
If it is not determined that the specific signal has been received from the target access point even if the first determination process is repeatedly performed over a predetermined time period that is less than the time period during which the monitoring process is performed, a second determination process is performed. A second determination process execution unit that executes a determination process, wherein the second determination process determines at least some of the N channels according to a second rule different from the first rule. determining whether the specific signal has been received from the target access point via the wireless interface using according to, wherein the second rule includes the plurality of DFS channels. the second decision processing execution unit , which is a rule including sequentially utilizing each of a plurality of channels including the plurality of non-DFS channels and the plurality of non-DFS channels ;
In the first determination process or the second determination process, the specific signal is received from the target access point using a second channel different from the first channel among the N channels. a second establishing unit that establishes a second wireless connection with the target access point via the wireless interface using the second channel when it is determined that the
A computer program that acts as

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