JP2021087173A - Terminal device - Google Patents

Abstract

To provide a terminal device that can establish a radio connection with a proper device while preventing an effect of fluctuations in the surrounding radio environment, etc.SOLUTION: A control unit (a) performs device searching for scanning each of a plurality of channels; (b) receives a plurality of packets from at least one external device among one or more surrounding external devices during the device searching; (c) stores, in a memory, reception record information including a used channel, a reception signal strength value, and device identification information for identifying a source external device of the packets at every packet reception during the device searching; (d) calculates a strength relationship value per device identification information from the corresponding reception signal strength value after the device searching; and (e) establishes a radio connection with a particular external device indicated by particular device identification information corresponding to the highest strength relationship value using a particular channel used by the particular external device.SELECTED DRAWING: Figure 4

Description

The technique disclosed herein relates to a terminal device capable of performing wireless communication using any one of a plurality of channels included in an available frequency band.

Patent Document 1 discloses a terminal device capable of performing wireless communication using any one of a plurality of channels included in an available frequency band. This terminal device uses the channel and receives one Beacon packet from the access points existing in the surroundings in each of the plurality of channels included in the frequency band in which the terminal device can be used. The terminal device monitors the radio field intensity value and channel when receiving a Beacon packet from each access point, and the terminal device should establish a wireless connection to the access point having the highest radio field strength value at the time of reception. Determine as the target access point. Then, the terminal device establishes a wireless connection with the determined target access point.

Japanese Unexamined Patent Publication No. 2005-142893

Generally, when there are a plurality of access points around the terminal device, the access point having the highest radio field intensity value at the time of receiving the Beacon packet is considered to be the optimum access point as the connection destination. However, in the technique of Patent Document 1, the value of the radio field intensity when the Beacon packet is received from each access point may differ from the original effective value due to factors such as fluctuations in the wireless environment around the terminal device. is there. As a result, in the technology of Patent Document 1, the access point that should be the most suitable as the connection destination is the target of the connection destination because it is affected by the fluctuation of the surrounding wireless environment when the terminal device receives each Beacon packet. It is possible that the access point will not be determined.

The present specification provides a terminal device capable of suppressing the influence of fluctuations in the surrounding wireless environment and establishing a wireless connection with an appropriate device.

The present specification discloses a terminal device capable of performing wireless communication using any one of a plurality of channels included in the available frequency band. The terminal device includes a control unit and a memory. The control unit executes (a) a device search process for executing a scan process for searching for a device using the channel for each of the plurality of channels, and (b) in the device search process, the surroundings. A plurality of packets are received from at least one external device among one or more external devices existing in the device, and (c) each time the packet is received in the device search process, the packet is used at the time of reception. Reception record information including the channel, the received radio wave intensity value at the time of receiving the packet, and the device identification information for identifying the external device that is the source of the packet is stored in the memory, and (d) After executing the device search process, the plurality of reception record information stored in the memory is referred to, and for each device identification information, an intensity-related value is calculated based on the corresponding received radio wave intensity value. e) Establish a wireless connection with a particular external device indicated by the particular device identification information corresponding to the highest intensity relationship value using the particular channel used by the particular external device.

According to the above configuration, the control unit receives a plurality of packets from at least one external device among one or more external devices existing in the vicinity by the device search process, and determines the strength relation value based on the plurality of packets. Calculate and establish a wireless connection with the specific external device corresponding to the highest value. Therefore, according to the above configuration, there are a plurality of configurations as compared with the conventional configuration in which the external device to be connected is specified based on the radio field strength value when one packet (for example, Beacon packet) is received from each external device. The strength-related value calculated using the radio field strength value when a packet is received is relatively small in the influence of fluctuations in the wireless environment and the like. Therefore, according to the above configuration, the terminal device can suppress the influence of fluctuations in the surrounding wireless environment and establish a wireless connection with an appropriate external device.

The intensity-related value may include an average radio wave intensity value obtained by averaging a plurality of corresponding received radio wave intensity values for each device identification information.

According to this configuration, the control unit receives a plurality of packets from at least one external device among one or more external devices existing in the vicinity by the device search process, and receives the packets for each device. The average radio field strength value, which is the average of the radio wave strength values at the time, can be calculated. Then, the control unit can identify a specific external device corresponding to the highest average radio field intensity value and establish a wireless connection with the specific external device. Therefore, according to this configuration, it is possible to average the influence of fluctuations in the wireless environment at the time of receiving each packet. That is, according to this configuration, the influence of fluctuations in the wireless environment at the time of receiving each packet can be reduced. Therefore, according to this configuration, the terminal device can establish a wireless connection with a suitable external device.

The reception record information may further include packet content information indicating the content of the packet, in addition to the channel used, the received radio wave intensity value, and the device identification information. After executing the device search process, the control unit further refers to the plurality of received record information stored in the memory, and for each device identification information, at least one corresponding packet content information is obtained. , It is determined whether or not the packet is output by the access point, and when at least one packet content information indicates the content related to the access point, the strength of the corresponding device identification information is obtained. When the relational value is calculated and none of the packet content information indicates the content related to the access point, the strength relational value may not be calculated for the corresponding device identification information.

According to this configuration, the control unit refers to a plurality of reception record information after executing the device search process, and at least one corresponding packet content information is output by the access point for each device identification information. Judge whether or not to show that. In other words, the control unit determines whether or not the external device indicated by the device identification information is a device having characteristics as an access point. Then, when at least one packet content information indicates the content related to the access point (that is, when the corresponding external device has the characteristics as an access point), the control unit has a strength relationship with respect to the device identification information. When the value is calculated, but none of the packet content information indicates the content related to the access point (that is, when the corresponding external device does not have the characteristics as an access point), the strength of the device identification information is obtained. Do not calculate the relational value. Therefore, according to the above configuration, the control unit excludes external devices that do not have characteristics as access points (for example, devices that operate only as slave stations (stations) of wireless networks) from the candidates for connection destinations. Therefore, a specific external device can be appropriately specified from the external devices having characteristics as an access point. According to the above configuration, the terminal device can appropriately establish a wireless connection with a specific external device having characteristics as an access point.

When the control unit receives a plurality of packets from at least one external device among one or more external devices in the device search process, the control unit has a maximum of N predetermined packets from one external device. N may be an integer of 2 or more).

According to this configuration, the control unit receives up to N packets from the same external device when executing the device search process. That is, according to this configuration, the maximum number (upper limit value) of packets received from the same external device and used to calculate the intensity-related value of the radio wave intensity value at the time of reception is set to N. Since it is not necessary to continue the scan process until the control unit receives an excessive number of packets in order to calculate the intensity-related value, the execution period of the scan process in each channel can be shortened. As a result, the period required for the device search process can be shortened. Therefore, according to this configuration, the terminal device can identify a specific external device in a relatively short period of time from the start of the device search process.

When the control unit executes the scan process in the device search process, the control unit terminates the scan process for the channel regardless of the packet reception status when a predetermined period elapses from the start of the scan process. It may be.

According to this configuration, the execution period of the scan process in each channel is limited. That is, according to this configuration, it is possible to prevent the execution period of the scan process in each channel from becoming excessively long. Therefore, even with this configuration, the terminal device can identify a specific external device in a relatively short period of time from the start of the device search process.

The outline of the wireless communication system of the first embodiment is shown. A block diagram showing the configuration of the terminal device is shown. The flowchart of wireless connection processing is shown. The flowchart of the device search process of 1st Example is shown. An example of the equipment table is shown. The flowchart of the connection destination identification process is shown. The flowchart of the device search process of the 2nd Example is shown.

(First Example)
(System configuration; Fig. 1)
In the wireless communication system 2 shown in FIG. 1, the terminal device 10 is any one of a plurality of APs (abbreviation of Access Point) 50, 60, 70, etc. existing in a predetermined area (for example, in a predetermined building). It is a system for executing wireless communication with another device (for example, a server existing outside a building) by establishing a wireless connection with one of them. As shown in FIG. 1, the wireless communication system 2 includes a terminal device 10, AP50, 60, 70 and the like, and a terminal device 80 and the like. In the example of FIG. 1, only APs 50, 60, and 70 are shown, but in reality, the wireless communication system 2 may include APs other than these. Further, in the example of FIG. 1, only the terminal device 80 is shown in addition to the terminal device 10, but in reality, the wireless communication system 2 may include other terminal devices.

(Structure of terminal device 10; FIGS. 1 and 2)
The terminal device 10 is a portable terminal device, and is, for example, an information code reading device (so-called bar code handy terminal) for reading data recorded in various information codes such as a bar code and a two-dimensional code. For example, the terminal device 10 reads the data recorded in the information code attached to the luggage, the product, etc. existing in the predetermined area, and transmits the read data to the external device by Wi-Fi communication. It is a device. The terminal device 10 is carried by a user engaged in work in a predetermined area. In another example, the terminal device 10 is not limited to the information code reading device, but is not limited to a mobile phone (for example, a smartphone), a PDA, a notebook PC, a tablet terminal, an RFID (abbreviation of Radio Frequency Identification) reader / writer, or Wi-Fi. It may be any portable terminal device capable of performing communication. In yet another example, the terminal device 10 may be any stationary terminal device capable of executing Wi-Fi communication, such as a stationary PC.

As shown in FIG. 2, the terminal device 10 includes an operation unit 12, a display unit 14, a photographing unit 16, a Wi-Fi interface 18, a control unit 20, and a memory 22. In the following, the interface will be referred to as "I / F". The operation unit 12 includes a plurality of keys. The user can operate the operation unit 12 to input various instructions to the terminal device 10. The display unit 14 is a display for displaying various information. In the modified example, the operation unit 12 and the display unit 14 may be configured as a touch panel including both functions. The photographing unit 16 is a photographing means capable of photographing images of various information codes such as a bar code and a two-dimensional code. The control unit 20 can read (that is, decode) the data recorded in the information code based on the image of the information code photographed by the photographing unit 16.

The Wi-Fi I / F18 is an I / F for executing wireless communication according to the Wi-Fi method (hereinafter referred to as "Wi-Fi communication"). The Wi-Fi system is a wireless communication system that conforms to the standards established by the Wi-Fi Alliance. For example, the IEEE (Institute of Electrical and Electronics Engineers, Inc.) 802.11 standard and its equivalent standards. It is a wireless communication system based on (for example, 802.11a, 11b, 11g, 11n, etc.). In this embodiment, the terminal device 10 executes Wi-Fi communication based on the IEEE 802.11n standard via any one of AP50, 60, 70 and the like. In Wi-Fi communication based on the IEEE802.11n standard, two frequency bands of 2.4 GHz and 5.0 GHz can be used. The 2.4 GHz band includes 14 channels (1ch to 14ch) having different center frequencies. The 5.0 GHz band includes 19 channels (36ch to 140ch) having different center frequencies. In another example, the terminal device 10 may execute Wi-Fi communication based on another standard via any one of AP50, 60, 70 and the like in a predetermined area. The terminal device 10 establishes a wireless connection with any AP in a predetermined area according to the Wi-Fi method, and executes Wi-Fi communication with another device via the AP. Can be done.

The control unit 20 executes various processes according to the OS program 24 stored in the memory 22, the wireless connection control application program (hereinafter referred to as “wireless connection control application”) 26, and the like. The memory 22 is composed of a ROM (abbreviation of Read Only Memory), a RAM (abbreviation of Random Access Memory), and the like. The OS program 24 stored in the memory 22 is a program for realizing the basic operation of the terminal device 10. The wireless connection control application 26 is provided by the vendor of the terminal device 10, and is a wireless connection process for the terminal device 10 to select and connect to an appropriate AP as a connection destination in order to execute Wi-Fi communication (see FIG. 3). It is a program to execute. The details of the wireless connection process will be described later.

The memory 22 further executes a wireless connection process (see FIG. 3) to record reception record information related to the record of receiving packets from peripheral devices of the terminal device 10 (see FIG. 5). It also has a table storage area 28 for storing.

(Structure of AP50, 60, 70; FIG. 1)
AP50, AP60, and AP70 are all ordinary APs called wireless access points or wireless LAN routers. However, although the AP50, AP60, and AP70 are not wireless access point devices, they may be terminal devices or the like that function as APs. When the terminal device functions as an AP, for example, the terminal device is a communication device that supports the WFD (abbreviation of Wi-Fi Direct (registered trademark)) method established by the Wi-Fi Alliance, and is a WFD. There are cases where the system shifts to the G / O (abbreviation of Group Owner) state and operates as the master station of the wireless network, or the terminal device operates as SoftAP. Each of the AP50, AP60, and AP70 can execute Wi-Fi communication between its own device and a client device for which a wireless connection has been established, using a specific channel. A MAC address, which is unique identification information, is assigned to each of AP50, AP60, and AP70. The terminal device 10 can execute Wi-Fi communication with another device (for example, an external server, another terminal device, etc.) by establishing a wireless connection with any one of AP50, AP60, and AP70.

(Configuration of terminal device 80; FIG. 1)
The terminal device 80 shown in FIG. 1 is a portable terminal device. The terminal device 80 may be the same information code reading device as the terminal device 10, or may be any other terminal device. In this embodiment, the terminal device 80 is a client device that establishes a wireless connection with any one of AP50, AP60, and AP70 to perform Wi-Fi communication.

(Wireless connection processing; FIGS. 3 to 6)
The contents of the wireless connection process executed by the control unit 20 of the terminal device 10 according to the wireless connection control application 26 will be described with reference to FIGS. 3 to 6. In the wireless connection process, the terminal device 10 appropriately selects a specific AP, which is the connection destination AP, from the surrounding APs 50, 60, 70, etc., and establishes a wireless connection with the selected specific AP. It is a process to do. When the user of the terminal device 10 inputs a predetermined connection start operation in the operation unit 12, the control unit 20 starts the process of FIG. At this time, the reception record information is not recorded in the device table 100 (see FIG. 5) included in the table storage area 28 of the memory 22.

In S10, the control unit 20 first executes a device search process (see FIG. 4). The device search process will be described with reference to FIG. The device search process exists around the terminal device 10, and uses one of the channels to send some packet (for example, Beacon packet, Probe Response packet which is a response of Probe Request, data packet to be communicated, etc.). This is a process for searching for an output external device (AP50 to 70, terminal device 80, etc.).

(Device search process; Fig. 4)
In S20 of FIG. 4, the control unit 20 identifies one of the channels available to the terminal device 10. For example, in S20, the control unit 20 can specify 1ch in the 2.4 GHz band. The channel specified in S20 may be referred to as a "search target channel" below. Specifically, in S20, the control unit 20 sets the frequency band used by the Wi-Fi I / F 18 for communication in the search target channel (for example, 1ch).

In the following S22, the control unit 20 starts counting the integration timer. The integration timer is a limited period for executing a series of processes (see S24 to S40) for searching for external devices existing in the vicinity in the search target channel specified in S20. The upper limit period T1 of the integration timer is predetermined. In this embodiment, the upper limit period T1 of the integration timer is set to, for example, 100 ms.

In the following S24, the control unit 20 broadcasts the Probe Request packet using the search target channel specified in S20, and starts counting the predetermined scan timer. The Probe Request packet is a packet that exists around the terminal device 10 and is output to search for an AP (including a terminal device that functions as an AP) that uses the search target channel. The AP that has received the Probe Request packet can transmit the Probe Response packet to the terminal device 10 that is the source of the Probe Request packet as a response to the Probe Request packet. The Probe Response packet contains information (eg, SSID, etc.) about the Wi-Fi network formed by the AP. An external device that is not an AP (including a terminal device that functions as an AP) (for example, a client device that uses the search target channel) can also receive the Probe Request packet, but receives the Probe Request packet. However, the Probe Response packet cannot be sent. The scan timer is a time limit period for executing one process for monitoring the reception of the response to the Probe Request (that is, the Probe Response packet) in the search target channel. The scan timer is defined as a unit period during which probe request packets and probe response packets can be transmitted and received between the terminal device 10 and APs existing in the vicinity. The upper limit period T2 of the scan timer is also predetermined. As will be described later, in this embodiment, the upper limit period T2 of the scan timer is set to, for example, 20 ms.

Subsequently, the control unit 20 starts monitoring S26 and S34. In S26, the control unit 20 monitors the reception of packets from the outside. As described above, when the AP using the search target channel receives the Probe Request packet, it transmits a Probe Response packet. In addition to this, the AP periodically (for example, every 100 ms) outputs a Beacon packet containing network information such as the SSID of its own machine. Beacon packets are also packets that can be output by APs (including terminal devices that function as APs). Further, the AP can also transmit a data packet to be communicated by performing Wi-Fi communication with a client device having already established a wireless connection using the search target channel. On the other hand, a device (for example, a terminal device 80, etc.) that is not an AP but uses a search target channel also communicates with an AP that has already established a wireless connection as Wi-Fi communication is performed. Send the target data packet. The control unit 20 can receive the above-mentioned various packets from the AP that uses the search target channel and the device that uses the search target channel. When the control unit 20 receives some packet from an external device (including AP and a device other than AP) that uses the search target channel, the control unit 20 determines YES in S26 and proceeds to S28.

In S28, the control unit 20 refers to the received packet and identifies the MAC address of the device that is the source of the packet. The MAC address is unique identification information unique to the device.

In S30, the control unit 20 refers to the device table 100 in the table storage area 28, and the number of packets already received (number of received packets) corresponding to the MAC address specified in S28 is from a predetermined upper limit value N. Judge whether it is low or not. As will be described later, each time the control unit 20 receives a packet, the control unit 20 includes the search target channel at this point, the MAC address of the packet source, the radio wave strength at the time of packet reception (received radio wave strength), and the packet content. The actual information is recorded in the device table 100 (see FIG. 5) (S32). A maximum of N reception record information is recorded in the device table 100 for each MAC address. At this point, the number of reception record information including the MAC address specified in S28 (that is, the combination of the received radio field strength and the packet content corresponding to the MAC address in the device table 100) is N in the device table 100. If it is less than, the control unit 20 determines YES in S30 and proceeds to S32. On the other hand, at this point, if the number of received record information corresponding to the MAC address specified in S28 has already reached N in the device table 100, the control unit 20 determines NO in S30. Skip S32 and proceed to S34.

In S32, the control unit 20 records in the device table 100 the reception record information including the search target channel at this time, the MAC address specified in S28, the received radio wave intensity at the time of packet reception, and the packet content.

Here, the configuration of the device table 100 will be described with reference to FIG. In the example of FIG. 5, in the device table 100, reception record information related to the record of receiving packets as the terminal device 10 executes the device search process is recorded. The reception record information recorded in the device table 100 includes the band, the channel, the MAC address, the received radio wave intensity at the time of receiving the first to Nth packets, and the packet contents. In the example of FIG. 5, the average radio field intensity is associated with the reception record information recorded in the device table 100.

The "Band" column indicates the frequency band used by the source device for Wi-Fi communication. In this example, either 2.4 GHz or 5.0 GHz is recorded in the "Band" column.

The "Channel" column indicates the channel used by the source device for Wi-Fi communication. If the corresponding band is 2.4 GHz, any of 1ch to 14ch is recorded. If the corresponding band is 5.0 GHz, any of 36ch to 140ch is recorded.

The "MAC address" column indicates the MAC address of the source device. In the example of FIG. 5, the MAC address is simply described as "M11" and "M12" for the sake of simplicity.

The columns of "P1" to "PN" indicate the received radio wave intensity and the packet content at the time of receiving the packet for each of the first to Nth packets received from the device having the corresponding MAC address. The columns of "P1" to "PN" are divided into a column of received radio wave strength and a column of packet contents, respectively. The received radio field intensity is expressed in units [dBm]. The larger the value (closer to 0), the stronger the signal strength. The packet content indicates one of "Probe_Res", "Beacon", and "Data". "Probe_Res", "Beacon", and "Data" indicate that the contents of the received packet were "Probe Response packet", "Beacon packet", and "Data packet", respectively. No information is recorded in the corresponding columns corresponding to unreceived packets among the columns of "P1" to "PN". For example, in the example of FIG. 5, since the Nth packet from the device with the MAC address “M13” has not been received, information is recorded in the “PN” column corresponding to the MAC address “M13” in the device table 100. It has not been.

The "Average radio field strength" column indicates the average value of the received radio wave strength of the 1st to Nth packets received from the device having the corresponding MAC address. In the "Average radio field strength" column, a value is recorded when the connection destination identification process (see FIG. 6) described later is executed (S52).

However, the recording method of the reception record information in the device table 100 shown in FIG. 5 is only an example. The recording method of the received record information in the actual device table 100 is not limited to the example of FIG. 5, and any method may be adopted.

In S34, the control unit 20 monitors whether or not a predetermined upper limit period T2 has elapsed since the scan timer started counting in S24. When a predetermined upper limit period T2 (for example, 20 ms) has elapsed since the count of the scan timer was started in S24, the control unit 20 determines YES in S34 and proceeds to S36.

In S36, at this point, the control unit 20 monitors whether or not a predetermined upper limit period T1 has elapsed since the counting of the integration timer was started in S22. If a predetermined upper limit period T1 (for example, 100 ms) has elapsed since the counting of the integration timer was started in S22, the control unit 20 determines YES in S36 and proceeds to S42. On the other hand, if the predetermined upper limit period T1 has not yet elapsed since the counting of the integration timer was started in S22, the control unit 20 determines NO in S36 and proceeds to S38.

In S38, at this time, the control unit 20 determines whether or not the number of received packets for all the MAC addresses corresponding to all the search target channels recorded in the device table 100 has reached N. To judge. At this point, if the number of received packets for all the MAC addresses corresponding to all the search target channels recorded in the device table 100 has reached N, the control unit 20 determines YES in S38. And proceed to S42. The case of YES in S38 is the case where N packets, which is a predetermined upper limit value, have already been acquired from each device using the current search target channel, and the search is continued in the search target channel any more. This is the case when the need is low. On the other hand, at this point, if the MAC addresses recorded in the device table 100 include MAC addresses in which the number of received packets is less than N, the control unit 20 determines NO in S38. Proceed to S40. The case of YES in S38 is the case where less than N packets are acquired from at least some of the devices currently using the search target channel, and the search should be continued in the search target channel. Is.

In S40, the control unit 20 determines whether or not the MAC address in which the number of received packets is less than N is associated with the packet content indicating Probe Response or Beacon. When the MAC address in which the number of received packets is less than N is associated with the packet content indicating Probe Response or Beacon, the control unit 20 determines YES in S40 and returns to S24. If YES in S40, the device corresponding to the MAC address in which the number of received packets is less than N is the AP. In that case, the control unit 20 is made to continue the search in the search target channel. That is, in the returned destination S24, the control unit 20 broadcasts the Probe Request packet again and newly starts counting the scan timer. After that, the processing after S26 is re-executed. On the other hand, if the MAC address in which the number of received packets is less than N is not associated with the packet content indicating Probe Response or Beacon, the control unit 20 determines NO in S40 and proceeds to S42. If YES in S40, the device corresponding to the MAC address in which the number of received packets is less than N is likely to be a device other than the AP (for example, a client device). In that case, it is less necessary for the control unit 20 to continue the search in the search target channel.

In S42, has the control unit 20 already specified all the channels that can be used by the terminal device 10 (14 channels in the 2.4 GHz band and 19 channels in the 5.0 GHz band, for a total of 33 channels)? Judge whether or not. If there is an unspecified channel at this point, the control unit 20 determines NO in S42 and returns to S20. In the returned destination S20, the control unit 20 newly specifies another channel as a search target channel. Then, the control unit 20 re-executes each process after S22 for the newly specified search target channel. On the other hand, when the terminal device 10 has already specified all the channels that can be used, the control unit 20 determines YES in S42 and ends the device search process of FIG. When the device search process of FIG. 4 is completed, reception record information (that is, channel, MAC address, received radio field strength, and reception record information) indicating the record of receiving packets as a result of performing the device search process for all channels is recorded. The device table 100 (see FIG. 5) is completed.

After completing the device search process of FIG. 4 (see S10 of FIG. 3), the control unit 20 executes the connection destination identification process (see FIG. 6) in S12 of FIG. The connection destination identification process will be described with reference to FIG. The connection destination identification process is a process for selecting a specific AP which is a connection destination AP by using the result of the device search process of FIG. 4 and establishing a wireless connection with the selected specific AP.

(Connection destination identification process; Fig. 6)
In S50 of FIG. 6, the control unit 20 excludes the reception record information corresponding to the MAC address to which the packet content indicating the Probe Response or Beacon is not associated from the device table 100. This is because there is a high possibility that the device corresponding to the MAC address to which the packet content indicating Probe Response or Beacon is not associated is not an AP. For example, in the example of FIG. 5, the packet content corresponding to the MAC address “M13” is only “Data” (that is, a data packet) and does not include Probe Response or Beacon. In that case, in S50, the control unit 20 excludes the reception record information corresponding to the MAC address “M13” from the device table 100. The exclusion method is arbitrary, for example, it may be completely deleted from the device table 100, or a flag may be associated so that it will not be used in the subsequent processing.

In the following S52, the control unit 20 determines the received radio field strength for each MAC address (for example, the MAC address “M11” in FIG. 5) with respect to the reception record information remaining in the device table 100 (that is, not excluded). Calculate the average radio field strength, which is the average value. In this embodiment, the control unit 20 records the calculated average radio field intensity in the device table 100 (see FIG. 5). However, in another example, the control unit 20 does not have to record the calculated average radio field intensity in the equipment table 100.

In the following S54, the control unit 20 identifies the MAC address corresponding to the highest average radio field strength among the average radio wave strength calculated in S52. For example, when the device table 100 of FIG. 5 is completed at this point, the average radio field intensity (-58.5 dbm) corresponding to the MAC address “M11” is the highest, so that the control unit 20 has the MAC address “ Identify "M11".

In the following S56, the control unit 20 communicates with the specific AP corresponding to the MAC address specified in S54 (hereinafter, may be referred to as "specific MAC address") and the channel used by the specific AP. Use to establish a wireless connection. Specifically, the control unit 20 executes communication of various signals (for example, Authentication signal, Association signal, 4-way handshake, etc.) with a specific AP via Wi-Fi I / F18. In the process of communicating the various signals described above, the control unit 20 transmits network information (specifically, SSID, password, etc.) for establishing a wireless connection with the specific AP to the specific AP, and the AP. Information authentication, that is, authentication of the terminal device 10 is performed by a specific AP. As a result, the control unit 20 establishes a wireless connection with the specific AP and causes the terminal device 10 to participate in the Wi-Fi network formed by the specific AP as a slave station. When S56 is completed, the control unit 20 ends the connection destination identification process of FIG. 6 and the wireless connection process of FIG.

The configuration and operation of the wireless communication system 2 of this embodiment have been described above. As described above, in the present embodiment, in the device search process of FIG. 4, the control unit 20 is a plurality (maximum N) from at least one external device among one or more external devices existing in the surroundings. The packet is received, the average reception strength is calculated based on the packet (S52 in FIG. 6), and a wireless connection is established with the specific AP corresponding to the highest value (S54, S56). Therefore, according to this embodiment, a plurality of packets are received as compared with the conventional configuration in which the external device to be connected is specified based on the radio field strength value when one packet is received from each external device. The intensity-related value calculated using the radio wave intensity value at the time is relatively small due to fluctuations in the wireless environment and the like. In addition, it is possible to suppress the occurrence of a situation in which an external device other than the AP in which a high radio field intensity value is accidentally detected only once is accidentally specified as a connection destination. Therefore, according to the configuration of this embodiment, the terminal device 10 can suppress the influence of fluctuations in the surrounding wireless environment and establish a wireless connection with an appropriate AP (external device).

Further, in the present embodiment, the control unit 20 receives a plurality of (maximum N) packets from at least one external device among one or more external devices existing in the vicinity in the device search process of FIG. The average radio field strength value, which is the average of the radio wave strength values when the packet is received, is calculated for each external device (more specifically, for each MAC address) after receiving the packet (S52 in FIG. 6). Then, the control unit 20 can identify a specific AP corresponding to the highest average radio field intensity value and establish a wireless connection with the specific AP (S54, S56). That is, in this embodiment, the influence of fluctuations in the wireless environment at the time of receiving each packet can be averaged. Therefore, the influence of fluctuations in the wireless environment at the time of receiving each packet can be reduced. Therefore, according to the configuration of this embodiment, the terminal device 10 can establish a wireless connection with an appropriate AP (external device).

Further, in this embodiment, in S50 of FIG. 6, the control unit 20 has a MAC address (that is, a device that is highly likely not an AP) to which the packet content indicating the Probe Response or Beacon is not associated with the device table 100. MAC address) reception record information is excluded. Then, in S52, the control unit 20 is associated with the reception record information (for example, information including the MAC address “M11” in FIG. 5) remaining in the device table 100 (that is, not excluded). Calculate the average radio field strength, which is the average value of the received radio field strength. That is, in this embodiment, the control unit 20 excludes external devices having no characteristics as APs (for example, devices that operate only as clients (slave stations, stations) of wireless networks) from the candidates for connection destinations. In the above, a specific AP (external device) can be appropriately specified from the external devices having the characteristics as an AP. According to this embodiment, the terminal device 10 can appropriately establish a wireless connection with a specific AP having characteristics as an AP.

Further, in the present embodiment, the control unit 20 receives a maximum of N packets from one external device that uses the search target channel in the device search process of FIG. 4 (see S30). In order to calculate the average radio field strength, it is not necessary to continue the scan process until the control unit 20 receives an excessive number of packets, so that the scan process execution period (execution period of S24 to S40) in each channel is shortened. Can be done. As a result, the period required for the device search process of FIG. 4 can be shortened. Therefore, according to this embodiment, the terminal device can identify a specific AP in a relatively short period of time from the start of the device search process.

Further, in the present embodiment, the control unit 20 receives the packet when a predetermined period T1 (for example, 100 ms) has elapsed (YES in S36) since the counting of the integration timer was started in S22 of FIG. Regardless of the situation, the scan process for the search target channel is terminated (S42). That is, in this embodiment, the execution period of the scan process in each search target channel is limited. That is, according to this embodiment, it is possible to prevent the execution period of the scan process in each search target channel from becoming excessively long. Therefore, the terminal device 10 can identify a specific AP in a relatively short period of time from the start of the device search process.

The correspondence between this embodiment and the description of the claims will be described. The processes S24 to S40 in FIG. 4 are an example of the “scan process”. Information including the channel, MAC address, received radio wave strength, and packet content when the packet is received is an example of "reception record information". The average radio field intensity calculated in S52 of FIG. 6 is an example of the “intensity-related value”. The device identification information is an example of "MAC address". A specific AP is an example of a "specific external device".

(Second Example)
The second embodiment will be described with reference to FIG. 7, focusing on the differences from the first embodiment. The basic configuration of the wireless communication system 2 of this embodiment is the same as that of the first embodiment. In this embodiment, as shown in FIG. 7, a part of the content of the device search process is different from that in the first embodiment. In the first embodiment, in the device search process, the control unit 20 actively executes a so-called active scan for transmitting a Probe Request packet, but in this embodiment, the control unit 20 receives a Beacon packet from an external device. Perform a so-called passive scan to monitor reception. Hereinafter, the content of the device search process of this embodiment will be described with reference to FIG. 7.

(Device search process; Fig. 7)
In S120 of FIG. 7, similarly to S20 of FIG. 4, the control unit 20 identifies one of the channels that can be used by the terminal device 10. In S122, the control unit 20 starts counting the integration timer. In this embodiment, the upper limit period T11 of the integration timer is set to, for example, 200 ms.

In S124, the control unit 20 starts counting the scan timer. In S124, the control unit 20 does not broadcast the Probe Request packet. In this embodiment, the upper limit period T12a of the first scan timer is set to, for example, 100 ms.

Subsequently, the control unit 20 starts monitoring S126 and S134. In S126, the control unit 20 monitors the reception of packets from the outside. In this embodiment, the control unit 20 can receive Beacon packets and data packets from the AP that uses the search target channel. In addition, the control unit 20 can also receive data packets from devices other than the AP using the search target channel. At this point, since the control unit 20 has not broadcast the Probe Request packet in S124, the Probe Response is not received.

Subsequent processing of S128, S130, and S132 is the same as that of S28, S30, and S32 of FIG.

In S134, the control unit 20 monitors whether or not a predetermined upper limit period T12a has elapsed since the scan timer started counting in S124. When the upper limit period T12a (for example, 100 ms) has elapsed since the count of the scan timer was started in S124, the control unit 20 determines YES in S134 and proceeds to S136.

In S136, at this point, the control unit 20 monitors whether or not the upper limit period T11 of the predetermined integration timer has elapsed since the counting of the integration timer was started in S122. If the upper limit period T1 (for example, 200 ms) has elapsed since the counting of the integration timer was started in S122, the control unit 20 determines YES in S136 and proceeds to S142. On the other hand, if the upper limit period T11 has not yet elapsed since the counting of the integration timer was started in S122, the control unit 20 determines NO in S136 and proceeds to S138.

The processing of S138 is the same as that of S38 in FIG. If the control unit 20 determines YES in S138, the control unit 20 proceeds to S142, and if it determines NO in S138, the control unit 20 proceeds to S140. The processing of S142 is also the same as that of S42 of FIG.

The processing of S140 is the same as that of S40 of FIG. However, in this embodiment, if the control unit 20 determines YES in S140, the control unit 20 proceeds to S141 before returning to S124.

In S141, the control unit 20 broadcasts the Probe Request packet using the search target channel. After that, the control unit 20 returns to S124 and starts counting the scan timer again. In the second and subsequent S124s, the upper limit period T12b of the scan timer is set shorter than the first upper limit period T12a. For example, the upper limit period T12b for the second and subsequent times is set to 20 ms (similar to the period T2 of the first embodiment). Since the control unit 20 broadcasts the Probe Request packet in S141, the control unit 20 can also receive the Probe Response in the second and subsequent S126s.

The configuration and operation of the wireless communication system 2 of this embodiment have been described above. As described above, in this embodiment, the control unit 20 executes a so-called passive scan that monitors the reception of Beacon packets. Since the AP periodically outputs the Beacon packet, the terminal device 10 can exert the same effect as that of the first embodiment.

Further, in the present embodiment, in S141 after the upper limit period T12a (100 ms) of the first scan timer has elapsed, the control unit 20 broadcasts the Probe Request packet using the search target channel. The upper limit period T12b of the second and subsequent scan timers is set as short as the period T2 of the first embodiment (for example, 20 ms). After that, the control unit 20 also receives the Probe Response from the outside as in the first embodiment. That is, in this embodiment, the active scan is executed instead of the passive scan from the second time onward. In general, if only passive scans are continuously executed, packet reception depends on the output cycle of Beacon packets of each AP, so it may take a long time to receive packets multiple times. .. Therefore, in this embodiment, the period required for the device search process is shortened by limiting the number of times the passive scan is executed to one.

The correspondence between this embodiment and the description of the claims will be described. The processes S124 to S140 and S141 in FIG. 7 are an example of the “scan process”.

(Modification 1) The reference value for the control unit 20 to select a specific AP (specific external device) may be a value other than the average radio field strength as long as it is a value related to the radio wave strength. That is, in S52 of FIG. 6, the control unit 20 may calculate other intensity-related values instead of calculating the average radio wave intensity. For example, the control unit 20 may calculate a value obtained by averaging the remaining values excluding the maximum value and the minimum value of the N received radio wave intensities. In still another example, the control unit 20 may exclude the intensity value of the received radio wave intensity equal to or less than a predetermined threshold value (so-called cutoff) and calculate the average value of the remaining intensity values. The values calculated in these modified examples are also examples of "strength-related values".

(Modification 2) The control unit 20 may omit the process of S50 in FIG. That is, the control unit 20 does not have to exclude the reception record information of the MAC address to which the packet content indicating the Probe Response or Beacon is not associated with the device table 100. In that case, in S52, the control unit 20 may calculate the average radio field intensity, which is the average value of the associated received radio wave strength, for all the MAC addresses in the device table 100.

(Modification 3) In the device search process (FIGS. 4 and 7), the control unit 20 receives an unlimited number of packets from one external device, and records the reception record information in the device table 100 each time it is received. It may be. That is, the determination of S30 in FIG. 4 and S130 in FIG. 7 may be omitted.

(Modification 4) On the contrary, in the device search process (FIGS. 4 and 7), the control unit 20 reaches the time when the number of packets received from any predetermined number of external devices reaches N, which is the upper limit value. Then, the scan process in the search target channel may be terminated regardless of the count value of the integration timer.

(Modification 5) In the above embodiment, the terminal device 10 corresponds to both the 2.4 GHz band and the 5.0 GHz band. Not limited to this, the terminal device 10 may support only one of the 2.4 GHz band and the 5.0 GHz band.

In addition, the technical elements described in the present specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the techniques illustrated in the present specification or drawings achieve a plurality of objectives at the same time, and achieving one of the objectives itself has technical usefulness.

2: Wireless communication system 10: Terminal device 12: Operation unit 14: Display unit 16: Imaging unit 18: Wi-Fi I / F
20: Control unit 22: Memory 24: OS program 26: Wireless connection control application 28: Table storage area 80: Terminal device 100: Device table

Claims (5)

A terminal device capable of performing wireless communication using any one of a plurality of channels included in an available frequency band.
Control unit and
Equipped with memory,
The control unit
(A) For each of the plurality of channels, a device search process for executing a scan process for searching for a device using the channel is executed.
(B) In the device search process, a plurality of packets are received from at least one external device among one or more external devices existing in the vicinity.
(C) Each time the packet is received in the device search process, the channel used at the time of receiving the packet, the received radio wave intensity value at the time of receiving the packet, and the external device that is the source of the packet are identified. The device identification information and the reception record information including the device identification information are stored in the memory.
(D) After executing the device search process, the plurality of reception record information stored in the memory is referred to, and the intensity-related value is calculated for each device identification information based on the corresponding received radio wave intensity value. And
(E) Establishing a wireless connection with a specific external device indicated by the specific device identification information corresponding to the highest intensity relation value using a specific channel used by the specific external device.
Terminal equipment. The terminal device according to claim 1, wherein the intensity-related value includes an average radio wave intensity value obtained by averaging a plurality of corresponding received radio wave intensity values for each device identification information. The reception record information further includes the packet content information indicating the content of the packet, in addition to the channel used, the received radio wave intensity value, and the device identification information.
The control unit further
After executing the device search process, the access point outputs at least one corresponding packet content information for each device identification information by referring to the plurality of reception record information stored in the memory. Determine if it indicates that it is a packet,
When at least one packet content information indicates content related to the access point, the strength-related value is calculated for the corresponding device identification information.
The terminal device according to claim 1 or 2, wherein the strength-related value is not calculated for the corresponding device identification information when none of the packet content information indicates the content related to the access point. When the control unit receives a plurality of packets from at least one external device among one or more external devices in the device search process, the control unit has a maximum of N predetermined packets from one external device. The terminal device according to any one of claims 1 to 3, wherein N receives a packet of 2 or more). When executing the scan process in the device search process, the control unit ends the scan process for the channel regardless of the packet reception status when a predetermined period elapses from the start of the scan process. The terminal device according to any one of claims 1 to 4.

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