JP5262734B2 - Wireless communication apparatus and program - Google Patents

Description

The present invention relates to a wireless communication apparatus and a program.

For example, in the case of the communication standard “IEEE802.15”, the frequency band used for wireless communication is a 2.4 [GHz] band. The wireless communication is performed by any one channel obtained by dividing the 2.4 [GHz] band into 16 channels.
Which channel is used is determined based on the electric field strength of each channel scanned by the coordinator.

  Here, the coordinator refers to a node that starts up the network, and the node refers to each element constituting the network. A node that performs wireless communication with the coordinator and transmits and receives beacons is referred to as a network device here.

Of the electric field intensities of the channels scanned by the coordinator, the channel with the lowest electric field intensity is determined as a channel (hereinafter referred to as a used channel) used in wireless communication between the coordinator and the network device.
The channel with the lowest electric field strength is the channel with the least radio wave interference between the channels and the optimum communication status. By using the channel with the lowest electric field strength as the channel to be used, it is possible to avoid a decrease in communication speed and disconnection of connection.

  According to Patent Document 1, a technique for assigning a use channel based on a ratio between the electric field strength of a desired station and the electric field strength of an interference station is disclosed.

Japanese Patent Laid-Open No. 11-88256

  However, in the technique of Patent Document 1, the allocated use channel is not always optimal in the communication state because the radio wave interference is always small during wireless communication. Even when the channel is optimal at the time of allocation, the communication speed is lowered and the connection is interrupted depending on the usage status of other channels and other wireless communication environments.

  An object of the present invention is to provide a wireless communication apparatus and a program that can avoid radio wave interference in a channel used and can always perform stable wireless communication.

According to the present invention,
In a wireless communication device that performs wireless communication with a network device,
A determination unit that determines the scanning timing of the electric field intensity;
A first communication unit that scans electric field strengths of a plurality of channels at the scan timing;
A second communication unit for transmitting a beacon to the network device;
A control unit that determines an optimum channel of the communication status based on the electric field intensity scanned by the first communication unit, and includes the information of the determined channel in the beacon;
Equipped with a,
When the control unit detects radio wave interference between the second communication unit and the network device, a wireless communication device is provided that switches the channel in use to the optimum channel of the determined communication status .

  According to the present invention, the channel used can be switched as appropriate, and radio wave interference can be avoided to ensure a stable communication speed or connection state at all times.

It is a figure which shows a radio | wireless communications system. It is a figure which shows the internal structure of a radio | wireless communication apparatus. It is a flowchart which shows the communication processing of a radio | wireless communications system. It is a flowchart which shows a channel information transmission process. It is a flowchart which shows the process of a radio | wireless communication apparatus in detail. It is a figure which shows an example of a scanning result.

FIG. 1 shows a wireless communication system 100 in the present embodiment.
The wireless communication system 100 includes a wireless communication device 10 connected to a wired LAN (Local Area Network) and one or a plurality of network devices 20.
The wireless communication system 100 transmits and receives beacons between the wireless communication apparatus 10 and the network device 20 by, for example, a wireless PAN (Personal Area Network) using the communication standard “IEEE802.15”.

FIG. 2 shows an internal configuration of the wireless communication apparatus 10 in the present embodiment.
The wireless communication device 10 includes an I / F unit 1, a buffer 2, a control unit 3, a timer 4, a storage unit 5, a SW 6, an antenna ANT, a first communication unit C1, a second communication unit C2, and a third communication unit. C3 etc. are comprised. Each unit is connected by a bus BS, and the wired LAN is connected to the I / F unit 1.

  The I / F unit 1 is configured by a bus interface such as USB (Universal Serial Bus), and inputs data from the wired LAN and outputs the data to a buffer.

The buffer 2 is configured by a semiconductor memory such as a RAM (Random Access Memory), and receives and temporarily stores data output from the I / F unit 1.
The data temporarily stored in the buffer 2 is transmitted to the network device 20 by a beacon.

The control unit 3 includes a CPU (Central Processing Unit), a RAM, a ROM (Read Only Memory), and the like, and centrally controls each unit of the wireless communication device 10 in cooperation with the storage unit 5.
The processing performed by the control unit 3 will be described later with reference to the flowcharts in FIG.

The timer 4 periodically determines the electric field intensity scan timing. Specifically, the timer 4 measures the electric field strength scan timing, and outputs a signal to that effect to the control unit 3 when the measured time reaches the scan timing.
The timer 4 determines the scan timing a plurality of times according to the radio communication time between the radio communication device 10 and the network device 20.

  The storage unit 5 is configured by a nonvolatile memory such as an HDD (Hard Disk Drive) and stores various programs and various data. Various data includes, for example, scan results (see FIG. 6).

SW6 is installed between the first communication unit C1, the second communication unit C2, the third communication unit C3, and the antenna ANT, and switches the communication units (C1 to C3) connected to the antenna ANT.
A plurality of antennas ANT may be installed corresponding to the communication units (C1 to C3) (for example, antennas ANT1, ANT2, and ANT3). In this case, SW6 is not installed.

The first communication unit C1 includes a demodulation circuit, an RF (Radio Frequency) circuit, and the like (not shown).
The first communication unit C1 periodically scans the electric field strength at the scan timing determined by the timer 4. In the present embodiment, the first communication unit C1 scans the electric field strength of 11 to 26 channels (for 16 channels) and performs this for a predetermined number of times (for example, 30 times).
The first communication unit C1 outputs the scan result to the storage unit 5.

The second communication unit C2 and the third communication unit C3 are configured to include a modulation circuit, a demodulation circuit, an RF circuit, and the like (not shown).
The second communication unit C2 and the third communication unit C3 modulate a beacon configured by data encoding and transmit the modulated beacon to the network device 20.
The second communication unit C2 and the third communication unit C3 demodulate the beacon and output it to the storage unit 5.
In addition, an input unit or a display unit (not shown) may be provided.

With reference to FIG. 3, the communication process of the radio | wireless communications system 100 is demonstrated.
The control unit 3 establishes a network with the network device 20 through the second communication unit C2 (step S1).
The control unit 3 performs channel information transmission processing (step S2).

The channel information transmission process will be described with reference to FIG.
The controller 3 uses the first communication unit C1 to scan the electric field strength of a predetermined channel to be scanned (hereinafter referred to as “scan channel”) by a predetermined number of times (hereinafter referred to as “scan number”) (step S21).
In this embodiment, the number of scan channels is 16 channels of 11 to 26, and the number of scans is 30.

  Based on the scan result, the control unit 3 determines an optimum channel with less radio wave interference and a communication state, and determines the information of the determined channel (hereinafter, channel information) as the second communication unit C2 and the third communication unit C3. (Steps S22a and S22b).

The control unit 3 includes channel information in the beacon (step S23).
The control unit 3 transmits a beacon including channel information to the network device 20 by the second communication unit C2 (step S24).

  The network device 20 receives the beacon transmitted from the second communication unit C2 (step S25), and stores the channel information included in the received beacon in a storage unit (not shown) (step S26).

The wireless communication system 100 ends the channel information transmission process after performing the processes of steps S21 to S26 one or more times.
For convenience of explanation, the wireless communication system 100 returns to the processing shown in FIG. 3 after returning to the processing shown in FIG. 4 (returns to step S3), but actually during the communication processing (see FIG. 3). The channel information transmission process (see FIG. 4) is periodically performed. Specifically, the wireless communication system 100 performs the processes of steps S3 to S9 in FIG. 3 to be described later and steps S21 to S26 of FIG. 4 described above in parallel.

Returning to FIG. 3, the control unit 3 transmits and receives beacons to and from the network device 20 by the second communication unit C2 (step S3).
The channel used for beacon transmission / reception is a channel included in the channel information stored in the network device 20 (see step S26 in FIG. 4).

When the control unit 3 detects radio wave interference between the second communication unit C2 and the network device 20 (step S4), the control unit 3 changes the communication unit used for beacon transmission / reception from the second communication unit C2 to the third communication unit. Switch to C3 (step S5).
On the other hand, when the network device 20 detects radio wave interference, the network device 20 switches channels based on channel information stored in a storage unit (not shown) (step S6).

The control unit 3 detects radio wave interference when the electric field strength of the channel used increases, or when a long time elapses before receiving an ACK from the network device 20.
The network device 20 detects radio wave interference when the beacon cannot be transmitted to the second communication unit C2.

The control unit 3 transmits a beacon to the network device 20 through the third communication unit C3 (step S7).
The control unit 3 establishes a network with the network device 20 through the third communication unit C3 (step S8), and transmits and receives beacons with the network device 20 (step S9).

The control unit 3 starts transmission processing of channel information again (step S10), and ends communication processing when beacon transmission / reception is completed between the third communication unit C3 and the network device 20.
Here, for convenience of explanation, the channel information transmission process is performed again. However, as described above, the channel information transmission process (see FIG. 4) is performed in parallel with the communication process (see FIG. 3). Done.

With reference to FIG. 5, the process of the radio | wireless communication apparatus 10 is demonstrated in detail.
The process illustrated in FIG. 5 is a detailed process performed by the wireless communication device 10 among the processes illustrated in FIGS. 3 and 4.

The control unit 3 reads the initial setting stored in the storage unit 5 (step S31).
The initial setting includes setting of a scan channel, the number of scans, and a threshold value.

  As described above with reference to FIG. 4, the scan channel is a channel to be scanned. The number of scans refers to the number of times to be scanned, and the number of scans when the entire electric field intensity of the scan channel that is initially set is scanned is one. The threshold value is a reference value for determining the magnitude of radio wave interference and can be set arbitrarily.

  In this embodiment, the default scan channel is “11 to 26 channels”, the number of scans is “30”, and the threshold is “12”.

  The control unit 3 starts association with the second communication unit C2 (step S32), and establishes a network with the network device 20 (step S33).

The control unit 3 scans the electric field intensity based on the initial setting read in step S31 by the first communication unit C1 (step S34).
The control unit 3 stores the scan result scanned by the first communication unit C1 in the storage unit 5 (step S35).

The control unit 3 determines whether or not all the electric field strengths of the scan channels that are initially set have been scanned (step S36).
The scan channels that are initially set are here 11 to 26 channels.

  When all the electric field strengths of the scan channels that are initially set are not scanned (step S36; N), the control unit 3 proceeds to step S34.

When all the electric field intensities of the scan channels that have been initially set are scanned (step S36; Y), the control unit 3 determines whether or not the scan has been performed for the number of scans that has been initially set (step S37).
Here, the preset number of scans is 30 here.

  When the scan is not performed for the number of scans that is initially set (step S37; N), the control unit 3 proceeds to step S34.

  When scanning is performed for the number of scans that is initially set (step S37; Y), the control unit 3 stores the scan result in the storage unit 5 and ends the scanning of the electric field intensity by the first communication unit C1. (Step S38).

FIG. 6 shows an example of the scan result.
Row A1 indicates the channel number of the scan channel, and the scan channels of this embodiment are 11 to 26 channels.
Column B1 indicates the number of scans, and the number of scans in this embodiment is 30 times.
Column B2 shows the electric field strength of 20 channels for each number of scans. For example, the electric field strength at the 20th scan number is “0”.

Row A2 indicates the number of times that the electric field strength equal to or lower than the threshold is measured out of the total number of scans. The threshold here is “12”. For example, in the case of 20 channels, the number of times the electric field strength below the threshold is measured is 25 times.
It can be said that the greater the number of times below the threshold, the less the radio wave interference and the more optimal the communication status.

  Row A3 shows the average value of the electric field strength measured by the total number of scans. For example, in the case of 20 channels, the average value of the electric field strength is “10”. The smaller the average value, the more stable the communication status.

  Row A4 indicates one channel number for which the communication status is determined as the optimum channel. In the present embodiment, the 20 channels with the largest number of times below the threshold and the smallest average value of the electric field strength are determined.

  Returning to FIG. 5, the control unit 3 selects one or a plurality of channels having the largest number of times of measuring the electric field strength below the threshold based on the scan result (step S <b> 39).

The controller 3 determines whether there are a plurality of selected channels (step S40).
When there is not more than one (step S40; N), the control unit 3 proceeds to step S44.
According to the scan result shown in FIG. 6, the control unit 3 selects only 20 channels and proceeds to step S44.

  When there are a plurality of channels (step S40; Y), the control unit 3 selects a channel with the smallest average value of the electric field strength among the selected channels (step S41).

The controller 3 determines whether there are a plurality of selected channels (step S42).
When there is not more than one (step S42; N), the control unit 3 proceeds to step S44.
When there are a plurality (step S42; Y), the controller 3 selects the channel with the smallest channel number (step S43).

The control unit 3 determines the selected channel as the optimum channel for the communication status (step S44).
The control unit 3 notifies the second communication unit C2 of channel information including the determined channel information (step S45).
Similarly, the control unit 3 notifies channel information to the third communication unit C3 (step S46).

The control unit 3 transmits a beacon including channel information to the network device 20 by the second communication unit C2 (step S47).
The control unit 3 deletes the scan result (see FIG. 6) from the storage unit 5 (step S48), and ends the processing of the wireless communication device.
If wireless communication is continuously performed between the second communication unit C2 and the network device 20, the control unit 3 proceeds to step S31 and performs the above process again.

  As described above, according to the present embodiment, it is possible to periodically scan the electric field strength and periodically transmit the channel information to the network device.

  When radio wave interference occurs during radio communication, radio wave interference can be avoided and radio communication can be continued by switching to a channel included in the channel information.

  Further, based on the scan result, the channel having the largest number of times less than or equal to the threshold can be included in the channel information as the optimum channel in the communication status.

  Further, when there are two or more channels having the largest number of times less than or equal to the threshold value, the channel having the smallest average value of the electric field strength can be included in the channel information as the optimum channel in the communication situation.

  Further, when there are two or more channels having the smallest average value of the electric field intensity, the channel having the smallest channel number can be included in the channel information as the optimum channel in the communication state.

Moreover, it is good also as a radio | wireless communication apparatus provided with three communication parts.
Specifically, as a wireless communication device 10 including a first communication unit C1 that scans electric field strength, a second communication unit C2 that transmits channel information, and a third communication unit C3 that transmits and receives beacons. Also good. The second communication unit C2 can continuously transmit the channel information to the network device 20 even after the occurrence of radio wave interference, so that the channel can be switched appropriately.

DESCRIPTION OF SYMBOLS 100 Wireless communication system 10 Wireless communication apparatus 1 I / F part 2 Buffer 3 Control part 4 Timer 5 Memory | storage part 6 SW
ANT antenna C1 first communication unit C2 second communication unit C3 third communication unit 20 network device

Claims (6)

In a wireless communication device that performs wireless communication with a network device,
A determination unit that determines the scanning timing of the electric field intensity;
A first communication unit that scans electric field strengths of a plurality of channels at the scan timing;
A second communication unit for transmitting a beacon to the network device;
A control unit that determines an optimum channel of the communication status based on the electric field intensity scanned by the first communication unit, and includes the information of the determined channel in the beacon;
Equipped with a,
The control unit is a wireless communication apparatus that switches a channel in use to an optimum channel in the determined communication state when radio wave interference is detected between the second communication unit and the network device . The first communication unit scans the electric field strength of a plurality of channels a plurality of times,
The control unit determines, based on the electric field intensity scanned by the first communication unit, a channel having the largest number of times of measuring an electric field intensity equal to or less than a predetermined threshold as an optimum channel in the communication state. Item 2. The wireless communication device according to Item 1 . When there are two or more optimal channels for the determined communication status, the control unit has the smallest electric field intensity average value measured by scanning the plurality of times among the two or more determined channels. The wireless communication apparatus according to claim 2 , wherein the wireless communication apparatus determines again as an optimum channel of the communication status. When there are two or more optimal channels in the determined communication status, the control unit determines again the channel having the smallest channel number as the optimal channel in the communication status among the two or more determined channels. The wireless communication apparatus according to claim 3 . A third communication unit that transmits and receives beacons to and from the network device;
When the control unit detects radio wave interference between the second communication unit and the network device, the control unit switches the channel in use to the optimum channel in the determined communication state, and the third communication unit to transmit and receive continuously the beacon, claim 1-4 which continuously transmits a beacon including information of a channel switching said by the second communication unit in the previous channel switching the The wireless communication device according to one item. A computer built in a wireless communication device that performs wireless communication with a network device,
Determining means for determining the scanning timing of the electric field intensity;
First communication means for scanning electric field strengths of a plurality of channels at the scan timing;
A second communication means for transmitting a beacon to the network device;
Control means for determining an optimum channel of communication status based on the scanned electric field strength, and including information on the determined channel in the beacon.
A program that functions as
The control means is a program for switching a channel in use to an optimum channel in the determined communication status when radio wave interference is detected between the second communication means and the network device .

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