JP4978631B2 - Wireless communication device - Google Patents

Description

  The present invention relates to a wireless communication apparatus. In particular, the present invention relates to a wireless communication apparatus including a plurality of wireless communication means that use the same frequency band.

  2. Description of the Related Art Conventionally, there are wireless communication devices that perform data communication or telephone call by wireless communication. In such a wireless communication apparatus, even if the communication method differs between data communication and telephone call, the frequency bands used may overlap.

For example, wireless LAN (Wireless Local Area Network for data communication)
Indicated as WLAN. ) And digital cordless phone (Digital Cordless)
telephone, hereinafter referred to as DCL. ) Use the same frequency band of 2.4 GHz band.

  Here, frequency bands and frequency channels used by WLAN and DCL will be described with reference to FIG. FIG. 10 is a schematic diagram illustrating frequency bands and frequency channels used in WLAN and DCL.

  As shown in FIG. 10, each of the WLAN and DCL communication systems uses a frequency band (2.4 GHz band) from 2.4 GHz to 2.5 GHz. And in each communication system, the channel which divided | segmented the 2.4 GHz band into plurality is set. Hereinafter, in order to distinguish channels in each communication method, a channel used in WLAN is a WLAN channel, and a channel used in DCL is a DCL channel.

  In WLAN, the 2.4 GHz band is divided into 14 WLAN channels wch1 to wch14. The WLAN performs wireless communication by a direct spread method that directly spreads transmission data to one WLAN channel while continuously using one of the 14 WLAN channels.

  On the other hand, in the DCL, the 2.4 GHz band is divided into 89 DCL channels dch1 to dch89. The DCL changes (hops) a DCL channel to be used between, for example, 45 DCL channels selected in advance among 89 DCL channels at a predetermined cycle (for example, 1/100 second) called a hopping cycle. Wireless communication is performed by a frequency hopping method.

  In an environment in which a plurality of communication methods are mixed as described above, the same frequency band is used by each communication method, so that radio wave interference may occur between the communication methods. On the other hand, in Patent Documents 1 and 2 below, a Bluetooth module that performs wireless communication with Bluetooth (registered trademark), which is one of the wireless communication systems using the 2.4 GHz band, and IEEE802. 11b discloses a technique for preventing radio wave interference when a wireless LAN module that performs wireless communication in the same area is used.

JP 2002-198867 A JP 2002-198868 A JP 2004-364121 A

  However, the techniques disclosed in Patent Documents 1 and 2 do not consider the influence of other wireless communication terminals (hidden terminals) that are outside the communicable range and cannot be grasped by themselves. If such a hidden terminal exists, the wireless LAN module may be affected by the access point (so-called hidden terminal problem), and the influence extends to the Bluetooth module.

Further, the above Patent Document 3 discloses a technique related to an RTS / CTS (request to send / clear to send) method for avoiding the hidden terminal problem. However, radio wave interference in an environment where a plurality of communication methods are mixed is disclosed. Is not touched.

  The present invention has been proposed in view of the above problems. An object of the present invention is to provide a wireless communication apparatus capable of performing wireless communication by a plurality of communication methods using the same frequency band while suppressing radio wave interference.

A wireless communication device according to claim 1 of the present invention includes a main communication device and at least one sub communication device, and performs wireless communication between the main and sub communication devices and wireless communication with an external communication device. In the wireless communication device, the primary and secondary subcarriers are used by a first wireless communication system that uses one of a plurality of first wireless channels provided in a predetermined frequency band and switches the first wireless channel to be used at a predetermined cycle. First wireless communication means for performing wireless communication between communication devices, and second wireless having a wider bandwidth than the first wireless channel provided in the predetermined frequency band used by the first wireless communication means Second wireless communication means for performing wireless communication with the external communication device by a second wireless communication system that continuously uses the channel, and the second wireless communication means includes the external communication device. An RTS signal indicating a transmission request is transmitted to the device, a CTS signal indicating reception preparation completion is received from the external communication device, and the first wireless communication means is described in a frame of the RTS signal and the CTS signal Used in the first radio channel included in the band of the second radio channel used for radio communication with the external communication device during the NAV period during which transmission of other communication devices is prohibited There line switching of the first radio channel, the first radio communication unit detects the radio wave state of the plurality of first radio channel, based on a threshold, a plurality of first radio channels, used in a radio communication Distribution means for distributing to a good channel to be used and bad channels not to be used, wherein the second wireless communication means is distributed to the good channel by the distribution means The number of first radio channels is equal to or less than a first predetermined number, and is equal to or greater than a second predetermined number except for the first radio channel included in the band of the second radio channel used for radio communication with the external communication device. In this case, the RTS signal is transmitted to the external communication device .

  The wireless communication apparatus according to claim 2 of the present invention is characterized in that, in the wireless communication apparatus of claim 1, the second wireless communication means does not perform wireless communication during the NAV period.

  According to a third aspect of the present invention, in the wireless communication apparatus according to the first aspect, the second wireless communication means intermittently performs wireless communication during the NAV period.

A wireless communication device according to a fourth aspect of the present invention is the wireless communication device according to any one of the first to third aspects, wherein the main communication device is a base unit of a digital cordless telephone, and the sub communication device is:
The digital cordless telephone is a slave unit, the first wireless communication means is a digital cordless telephone system, the second wireless communication means is a wireless LAN system, and the external communication device is an access in the wireless LAN. It is a point.

According to the wireless communication apparatus according to claim 1 of the present invention, by using the RTS / CTS method, the first wireless communication unit can reduce the influence of radio wave interference and obtain a favorable communication environment. Can do. Furthermore, the first wireless communication means can secure the required number of good first wireless channels.

  According to the wireless communication device of the second to third aspects of the present invention, the second wireless communication unit reduces the influence on the wireless communication by the first wireless communication unit, and further improves the communication environment of the first wireless communication unit. can do.

According to the wireless communication apparatus of the fourth aspect of the present invention, it is possible to configure a wireless communication apparatus having a call function using a digital cordless telephone and a data communication function using a WLAN between the parent device and the child device.

  According to the wireless communication apparatus of the present invention, by using the RTS / CTS method, wireless communication using a plurality of communication methods using the same frequency band can be performed while suppressing radio wave interference.

It is an external view showing a multi-function device. It is a block diagram which shows the structure of a communication system. It is the schematic which shows the network which employ | adopted the communication system of FIG. It is a flowchart of the channel determination process of a multi-function device. It is a figure which shows a channel corresponding | compatible table. It is a flowchart of the RTS / CTS control process of a multi-function device. It is a figure which shows the frame format of a RTS signal and a CTS signal. It is a sequence diagram which shows operation | movement of each apparatus in the network of FIG. It is the schematic which shows the mode of the hopping of the DCL channel in RTS / CTS control processing. It is the schematic which showed the frequency band and frequency channel which are used by WLAN and DCL.

  Embodiments will be described with reference to the drawings. FIG. 1 is an external view showing a multi-function device 1 as an example of a wireless communication apparatus of the present invention. The multi-function device 1 includes a parent device 10 and a child device 61. The base unit 10 has a printer function, a FAX function, and the like as well as a WLAN function and a DCL function as a main body of the multi-function device 1. As shown in FIG. 1, a handset 23 is provided on the side surface of the base unit 10. Further, an operation key 15 and an LCD 16 with a touch panel function are provided in front of the upper surface of the base unit 10. The user can input a telephone number or the like into the base unit 10 via the operation keys 15 and the LCD 16.

FIG. 2 is a block diagram illustrating a configuration of a communication system including the parent device 10 and the child device 61. The base unit 10 includes a CPU 11, a ROM 12, a RAM 13, a WLAN communication control circuit 17, a DCL communication control circuit 19, a handset 23, a voice processing LSI 24, an NCU (Network Control Unit, hereinafter).
Below, it describes with NCU. ) 25. The CPU 11, ROM 12, and RAM 13 are connected to each other via a bus line 26. The handset 23 and the NCU 25 are connected to the voice processing LSI 24. The operation key 15, the LCD 16, the WLAN communication control circuit 17, the DCL communication control circuit 19, the voice processing LSI 24, the NCU 25, and the bus line 26 are connected to each other via the input / output port 27.

  The CPU 11 executes various processes according to programs and parameters stored in the ROM 12 and the RAM 13, or various signals transmitted / received via the WLAN communication control circuit 17, the DCL communication control circuit 19, and the NCU 25. The ROM 12 stores a program for controlling the parent device 10 and the child device 61 constituting the multi-function device 1, various tables that are referred to according to the program, and the like. The RAM 13 stores various data generated in the process that is executed according to the program.

  The WLAN communication control circuit 17 having the WLAN antenna 18 performs WLAN communication 200 that is wireless communication by a direct spreading method with an access point (hereinafter referred to as AP) 51 having the WLAN antenna 52. . The AP 51 is connected to the LAN 500, and the parent device 10 performs data communication with another device (for example, a PC) connected to the LAN 500 via the AP 51.

  The DCL communication control circuit 19 having the DCL antenna 20 performs DCL communication 300, which is radio communication by the frequency hopping method, with the DCL communication control circuit 62 having the DCL antenna 63 of the slave unit 61. The voice processing LSI 24 mutually converts the analog voice signal of the handset 23 and the NCU 25 and the digital signal of the DCL communication control circuit 19. The NCU 25 is connected to the telephone line network 100, and transmits a dial signal to the telephone line network 100, responds to a calling signal from the telephone line network 100, and the like.

  FIG. 3 is a schematic diagram illustrating an example of a network employing the communication system configured as described above. Base unit 10 performs WLAN communication 200 with AP 51 using WLAN channel wch5 and connects to LAN 500. The handset 61 makes a call with the base unit 10 and other telephones connected to the telephone line network 100 by DCL communication 300 with the base unit 10. In addition, PCs 71 and 72 which are other WLAN terminals exist around the parent device 10 and the child device 61. The PC 71 can send and receive signals only to and from the parent device 10. Since the PC 72 has the obstacle 81, the PC 72 can transmit and receive signals only with the AP 51. That is, base unit 10 and PC 72 are in a hidden terminal relationship in which the other party's signal cannot be detected.

  As already described, in the DCL, the 2.4 GHz band is divided into 89 DCL channels dch1 to dch89 (see FIG. 10). In the network of FIG. 3, the parent device 10 and the child device 61 perform the DCL communication 300 while hopping the DCL channel to be used among 45 DCL channels out of 89 DCL channels. At this time, the master unit 10 and the slave unit 61 select and use a DCL channel having the best radio wave condition as much as possible, but there are a lot of external noises when a plurality of WLAN channels set to the same frequency band are used. In this case, it is difficult to secure a good DCL channel. In the present embodiment, the multi-function device 1 including the parent device 10 and the child device 61 uses the RTS / CTS method to ensure a good DCL channel. Hereinafter, processing executed in the multi-function device 1 will be described with reference to FIGS. 4 to 9.

FIG. 4 is a flowchart of the channel determination process of the multi-function device 1 for determining the DCL channel used for the DCL communication 300. In S11, the multi-function device 1 detects 89 DCL channel radio wave conditions and distributes the DCL channels dch1 to dch89 into good channels used for DCL communication 300 and bad channels not used.
Determine the value. The detection of the radio wave condition is performed, for example, by measuring the noise level of each DCL channel by the DCL communication control circuit 62 of the handset 61.

  In S12, the multi-function device 1 sorts all the DCL channels dch1 to dch89 into a good channel and a bad channel based on the threshold value determined in S11. For example, if the noise level of each DCL channel is below a threshold value, the multi-function device 1 assigns it to a good channel, and if it exceeds the noise level, assigns it to a bad channel.

  In S <b> 13, the multi-function device 1 determines whether or not the number of good channels is 45 or more, that is, whether or not the number of good channels has been secured by the number required for the DCL communication 300. If the number of good channels is 45 or more (S13: YES), in S14, the multi-function device 1 uses the 45 DCL channels among the good channels that can be secured to perform DCL between the master unit 10 and the slave unit 61. Communication 300 is performed.

  On the other hand, when the number of good channels is less than 45 (S13: NO), in S15, the multi-function device 1 determines that the number of good channels included in the bandwidth of the WLAN channel used for the WLAN communication 200 with the AP 51. It is determined whether or not the value obtained by subtracting the number of channels is 23 or more, that is, whether or not the number of good channels is 23 or more other than the DCL channels included in the WLAN channel band used for the WLAN communication 200. To do. When the subtraction value is 23 or more (S15: YES), the multi-function device 1 performs the RTS / CTS control process of S20.

  Here, the calculation formula in S15 will be described. As already described, in the WLAN, the 2.4 GHz band is divided into 14 WLAN channels wch1 to wch14 (see FIG. 10). The ROM 12 of the base unit 10 stores a channel correspondence table as illustrated in FIG. 5 that associates each WLAN channel with a center frequency, a frequency range, and a DCL channel. As shown in FIG. 5, the bandwidth of the WLAN channel wch1 includes 22 DCL channels dch4 to dch25. Similarly, each of the bands of the WLAN channels wch2 to wch12 includes 22 DCL channels. The bandwidth of the WLAN channel wch13 includes 20 DCL channels, and the bandwidth of the WLAN channel wch14 includes 7 DCL channels.

  As will be described later, in the RTS / CTS control process of S20, the radio wave condition can be improved for the DCL channel included in the band of the WLAN channel used for the WLAN communication 200 with the AP 51. In the network of FIG. 3 according to the present embodiment, the WLAN channel wch5 is used for the WLAN communication 200 with the AP 51. Therefore, even if the 22 DCL channels dch26 to dch47 included in the band of the WLAN channel wch5 are allocated to the bad channels in S12, the radio wave condition is improved by the RTS / CTS control processing in S20 and used for the DCL communication 300. be able to. Therefore, in this embodiment, if the number of good channels is 23 or more other than the DCL channels included in the band of the WLAN channel wch5 used for the WLAN communication 200, the WLAN is performed by performing the RTS / CTS control process of S20. Together with the 22 DCL channels included in the band of the channel wch5, 45 DCL channels necessary for the DCL communication 300 can be secured.

On the other hand, when the subtraction value is less than 23 (S15: NO), the 45 DCL channels necessary for the DCL communication 300 cannot be secured even if the RTS / CTS control process of S20 is performed. Therefore, in S16, the multi-function device 1 changes the threshold value for distributing the DCL channel to the good channel and the bad channel. For example, the multi-function device 1 allows a DCL channel having a high noise level and a poor radio wave condition by increasing a threshold value. Threshold
After changing the value, the multi-function device 1 returns to S12 and assigns the DCL channel again.

  Next, the RTS / CTS control process of S20 will be described in detail with reference to the flowchart of FIG. In S <b> 21, the multi-function device 1 starts DCL communication 300 between the parent device 10 and the child device 61. In S <b> 22, the multi-function device 1 determines whether the DCL communication 300 has ended. When the DCL communication 300 has not ended (S22: NO), the multi-function device 1 determines whether or not the good channel can be used in S23. Here, in the DCL communication 300, 45 DCL channels are equally used. Therefore, the multi-function device 1 first performs the DCL communication 300 using the good channel, and determines that the good channel cannot be used in S23 when all the good channels are used.

  If the good channel can be used (S23: YES), the multi-function device 1 hops to the next DCL channel in S24 and returns to S22.

  On the other hand, when the good channel is not usable (S23: NO), the multi-function device 1 transmits / receives the RTS signal and the CTS signal to / from the AP 51 by the WLAN communication control circuit 17 of the parent device 10 in S25 and S26. .

Here, S25 and S26 will be specifically described. FIG. 7 shows an example of the frame format of the RTS signal and the CTS signal. The RTS signal is a signal indicating a transmission request to the AP 51. As shown in FIG. 7A, the frame of the RTS signal includes frame control, duration, receiver address, transmitter address, and error check. This is composed of FCS (Frame Check Sequence, hereinafter referred to as FCS). The CTS signal is a signal indicating that the AP 51 that has received the RTS signal indicates that reception preparation is complete. As shown in FIG. 7B, the frame of the CTS signal includes frame control, duration, receiver address, and Consists of FCS for error checking. The duration field of each frame of the RTS signal and the CTS signal includes a NAV (Network Allocation Vector, hereinafter)
Indicated as NAV. ) Describes the scheduled period of using the wireless line, called the period.

  FIG. 8 is a sequence diagram showing the operation of each device when the WLAN communication control circuit 17 of the base unit 10 transmits / receives an RTS signal and a CTS signal to / from the AP 51 in the network of FIG. 3 according to the present embodiment. is there. First, base unit 10 transmits an RTS signal to AP 51. The AP 51 that has received the RTS signal returns a CTS signal to the parent device 10 and transmits an ACK (Acknowledgment) as a confirmation response when reception of the transmission data frame from the parent device 10 is completed. During this time, since the PC 71 can send and receive signals to and from the parent device 10, the PC 71 also receives the RTS signal. The PC 71 that has received the RTS signal determines that the radio line is occupied during the NAV period described in the duration field of the frame of the RTS signal, and stops transmission from its own station. On the other hand, the PC 72 cannot receive the RTS signal because of the relationship between the parent device 10 and the hidden terminal. Therefore, the NAV period cannot be acquired from the RTS signal. However, since the PC 72 can receive the CTS signal transmitted by the AP 51, the PC 72 stops transmission from the own station during the NAV period described in the duration field of the frame of the CTS signal. Thereby, in the network of FIG. 3, other WLAN terminals existing around the parent device 10 and the child device 61 stop transmission. As a result, for the DCL channel included in the band of the WLAN channel wch5 used by the AP 51, during the NAV period, radio wave interference with WLAN communication performed by surrounding WLAN terminals including hidden terminals is avoided, and the radio wave condition is improved. be able to. Further, the WLAN communication control circuit 17 of the parent device 10 does not actually perform communication during the NAV period. Thereby, the influence of the WLAN communication 200 on the DCL communication 300 can be reduced, and the radio wave condition of the DCL channel included in the band of the WLAN channel wch5 used by the AP 51 can be further improved.

  As described above, when there are not enough good channels that can be hopped (S23: NO in FIG. 6), the multi-function device 1 transmits / receives the RTS signal and the CTS signal to / from the AP 51 by the WLAN communication control circuit 17 of the parent device 10. (FIG. 6 S25, S26). Thereby, in the network of FIG. 3, the radio wave condition of the DCL channel included in the band of the WLAN channel wch5 used for the WLAN communication 200 with the AP 51 can be improved during the NAV period. Therefore, the multi-function device 1 moves to S24 during the NAV period, hops to the DCL channel included in the band of the WLAN channel wch5 with improved radio wave conditions, and returns to S22.

  FIG. 9 is a schematic diagram showing DCL channel hopping in the RTS / CTS control process described so far. In FIG. 9, the DCL channel is indicated by diagonal lines. As shown in FIG. 9, the multi-function device 1 has a DCL channel included in a band other than the WLAN channel band used for the WLAN communication 200 with the AP 51 while there are enough good channels that can be hopped. Select a good channel from and hop. When there are not enough good channels that can be hopped, the multi-function device 1 transmits / receives the RTS signal and the CTS signal, and is included in the WLAN channel band used for the WLAN communication 200 with the AP 51 during the NAV period. Hops in the DCL channel. In this way, until the DCL communication 300 ends (S22: YES in FIG. 6), the multi-function device 1 performs the DCL communication 300 with reduced radio wave interference while using the 45 DCL channels equally.

Here, the correspondence with the claims is as follows.
The master device 10 is an example of a main communication device, the slave device 61 is an example of a sub communication device, the AP 51 is an example of an external communication device, and the multi-function device 1 is an example of a wireless communication device. The 2.4 GHz band is an example of a predetermined frequency band, the DCL channel is an example of a first wireless channel, the frequency hopping method is an example of a first wireless communication method, and the DCL communication control circuits 19 and 62 are first wireless communication means, respectively. The WLAN channel is an example of a second wireless channel, the direct spreading method is an example of a second wireless communication method, and the WLAN communication control circuit 17 is an example of a second wireless communication unit. Further, the distribution means is realized by S11 and S12 of the channel determination process of the multi-function device 1. Further, the determination reference value “45” in S13 of the channel determination process is an example of a first predetermined number, and the determination reference value “23” in S15 is a second predetermined number.

  As described above in detail, according to the embodiment of the present invention, for the DCL channel included in the WLAN channel band used by the AP 51, the WLAN performed by the surrounding WLAN terminals including the hidden terminal during the NAV period. It is possible to avoid radio wave interference with communication and improve radio wave conditions. In addition, since the WLAN communication control circuit 17 of the base unit 10 does not actually perform communication during the NAV period, the influence of the WLAN communication 200 on the DCL communication 300 is reduced and the radio wave condition of the DCL channel is further improved. Can do. Thereby, even when the number of good channels is less than the required number in the DCL communication 300, the radio wave condition can be improved by the RTS / CTS control process, and the required number of good DCL channels can be secured. A good communication environment can be provided for the DCL communication 300 that requires real-time communication and is easily affected by radio wave interference.

Needless to say, the present invention is not limited to the above-described embodiments, and various improvements and modifications can be made without departing from the spirit of the present invention.
For example, each flowchart in the above embodiment is merely an example, and the process may be realized by another flowchart as long as a result equivalent to the process of each flowchart can be obtained.

In the channel determination process of FIG. 4, detection of the radio wave condition of the DCL channel is performed in S11
Although it went, you may carry out by S12.

  Further, the reference value “23” for determination in S15 is not limited to this. For example, when the WLAN channel wch13 is used for the WLAN communication 200 with the AP 51, the bandwidth of the WLAN channel wch13 includes 20 DCL channels (see FIG. 5). Therefore, in order to secure the 45 DCL channels necessary for the DCL communication 300, the determination reference value in S15 may be set to “25”.

Furthermore, although the WLAN communication control circuit 17 of the parent device 10 does not actually perform communication during the NAV period, the present invention is not limited to this.
The WLAN communication control circuit 17 of the parent device 10 may perform intermittent communication, that is, communication with a low duty during the NAV period.
In addition, in the duration field of the frame of the RTS signal transmitted by the WLAN communication control circuit 17 of the parent device 10, a time longer than the time actually taken for transmission of the transmission data frame may be described. In this case, a DCL channel included in the band of the WLAN channel used for the WLAN communication 200 with the AP 51 may be used between the end of transmission of the transmission data frame and the end of the NAV period.

1 Multi-function device 10 Base device 17 WLAN communication control circuit 19, 62 DCL communication control circuit 51 Access point (AP)
61 Child machine

Claims (4)

In a wireless communication device comprising a main communication device and at least one sub communication device, performing wireless communication between the main and sub communication devices and performing wireless communication with an external communication device,
While using one of a plurality of first radio channels provided in a predetermined frequency band, the first and second communication devices are switched between the main and sub communication devices by a first radio communication system that switches the first radio channel to be used at a predetermined cycle. First wireless communication means for performing wireless communication;
The external communication by a second wireless communication system that continuously uses a second wireless channel having a wider bandwidth than the first wireless channel provided in the predetermined frequency band used by the first wireless communication means. Second wireless communication means for performing wireless communication with the device,
The second wireless communication means transmits an RTS signal indicating a transmission request to the external communication device, receives a CTS signal indicating completion of reception preparation from the external communication device,
The first wireless communication means is used for wireless communication with the external communication device during a period described in the frame of the RTS signal and the CTS signal and during which the transmission of other communication devices is prohibited. among the first radio channel included in the band of the second radio channel, it has rows switching of the first radio channel used,
The first wireless communication means detects radio wave conditions of the plurality of first wireless channels, and based on the threshold, the plurality of first wireless channels are classified into good channels used in wireless communication and bad channels not used. Provided with a sorting means for sorting,
The second wireless communication means has a first wireless channel number assigned to the good channel by the distribution means that is equal to or less than a first predetermined number and is used for wireless communication with the external communication device. A radio communication apparatus, wherein the RTS signal is transmitted to the external communication apparatus when the number is a second predetermined number or more excluding the first radio channel included in a band of two radio channels . The wireless communication apparatus according to claim 1, wherein the second wireless communication unit does not perform wireless communication during the NAV period. The wireless communication apparatus according to claim 1, wherein the second wireless communication unit performs wireless communication intermittently during the NAV period. The main communication device is a base unit of a digital cordless phone,
The sub-communication device is a handset of the digital cordless telephone;
The first wireless communication means is a digital cordless telephone system;
The second wireless communication means is a wireless LAN system;
The wireless communication device according to any one of claims 1 to 3 , wherein the external communication device is an access point in the wireless LAN.

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