JP3831404B2 - Wireless communication method - Google Patents

Description

The present invention relates to a wireless communication method and apparatus for performing communication control of a wireless LAN system, and more particularly to a wireless communication method and apparatus characterized by an operation when assigning a channel.

  In the wireless LAN system in IEEE 802.11, there are a plurality of usable frequency bands, and there are a plurality of channels in each band. The wireless LAN communication apparatus can perform communication by selecting an available channel from these channels. On the other hand, some of the plurality of frequency bands may coexist with other systems. For example, a radar system coexists in the 5 GHz band.

  Taking the case in Europe as an example, the frequency band that can be used in the wireless LAN system is a band from 5.15 GHz to 5.25 GHz, a band from 5.25 GHz to 5.35 GHz, and a band from 5.47 GHz to 5.725 GHz. is there. Among these frequency bands, the channels in the band from 5.15 GHz to 5.25 GHz are for indoor use and the transmission power is small, so there is no interference with the radar. There is no need to detect. On the other hand, the channel in the 5.25 GHz to 5.35 GHz band and the channel in the 5.47 GHz to 5.725 GHz band can be used outdoors and may interfere with the radar because the transmission power is large. When these bands are used, it is necessary to detect whether or not a radar signal exists. In these bands, the channel can be used only when a channel from which no radar signal is detected is selected.

In order to avoid interference with the radar when using the wireless LAN system in a frequency band where the radar system and the wireless LAN system coexist, the radar pulse is used at a time when the radar pulse and the signal of the wireless LAN system do not interfere with each other. There is a proposal to use a wireless LAN system as much as possible (for example, see Patent Document 1).
JP 2001-285301 A

  However, using the wireless LAN system only when the radar pulse does not interfere with the signal of the wireless LAN system using the periodicity of the radar is ETSI (ETSI: European Telecommunication Standards Institute) EN (EN: European standards) 301 The 893v1.2.2 standard violates the standard. That is, in the ETSI EN 301 893v1.2.2 standard, when a channel in the band of 5.25 GHz to 5.35 GHz and a channel in the band of 5.47 GHz to 5.725 GHz are used, the radar is detected. There is a stipulation that the time spent in the process must be 60 seconds or more. That is, when a channel in which the radar system and the wireless LAN system coexist is used, the wireless LAN system cannot communicate for at least 60 seconds after the power is turned on.

  In addition, in the European standard ETSI EN 301 893v1.2.2, there are channels that have to detect radar signals depending on the frequency band. When these channels are used, the radar signals are detected and the radar signals are detected by the channels. You need to make sure it doesn't exist. In addition, as for all channels in the frequency band that can be used in the wireless LAN system, it is necessary to make all the channels have the same usage rate, so it is not possible to continue using only channels that do not require radar signal detection. Accordingly, it is necessary to select a channel that needs to detect the radar signal, and in this case, a detection time of at least 60 seconds is required.

Accordingly, an object of the present invention is to provide a wireless communication method and apparatus capable of starting communication with almost no waiting time after operation to start communication when using a wireless LAN system. .

The wireless communication method of the present invention stores first information indicating at least one first communication channel usable in the radar system and second information indicating at least one second communication channel not usable in the radar system. When communicating in a certain wireless communication system, one third communication channel is randomly selected from a plurality of communication channels including at least one of the first communication channels and the second communication channel, and the first information is selected. Referring to the signal received on the selected third communication channel, it is determined whether or not it is necessary to detect whether or not it is currently used in the radar system, and when it is determined that the signal needs to be detected, Control is performed so as to start communication in the wireless communication system on the second communication channel, and a signal received on the third communication channel is currently used for the radar system. When it is detected whether or not it is used, and when it is detected that it is not used in the radar system, the communication in the wireless communication system is controlled to be switched to the third communication channel and used in the radar system. When it is detected that communication is being performed, communication in the wireless communication system is continued on the second communication channel.
The wireless communication method of the present invention includes first information indicating at least one first communication channel usable in the radar system and second information indicating at least one second communication channel not usable in the radar system. When storing and communicating in a wireless communication system, one third communication channel is randomly selected from a plurality of communication channels including at least one of the first communication channels and the second communication channel, and the first communication channel is selected. By referring to the information, it is determined whether or not the selected third communication channel matches any of the first communication channels, and whether or not the signal received on the third communication channel is currently used in the radar system. And when it is determined that they match, control is performed so that communication in the wireless communication system is started on the second communication channel, and the radar system is controlled. If it is detected that the radio communication system is not used, the radio communication system is controlled to switch the communication to the third communication channel. The communication in the communication system is continued on the second communication channel.
The wireless communication apparatus of the present invention stores first information indicating at least one first communication channel usable in the radar system and second information indicating at least one second communication channel not usable in the radar system. Storage means and selection means for randomly selecting one third communication channel from a plurality of communication channels including at least one of the first communication channels and the second communication channel when communicating in a certain wireless communication system; , Referring to the first information in the storage means, and determining means for determining whether the third communication channel selected by the selection means matches any of the first communication channels; and When the received signal is currently used in a radar system, the wireless communication is performed when the detection unit determines that the received signal matches the detection unit. If the detection means detects that the communication system is not used in the radar system, the communication in the wireless communication system is communicated with the third communication channel. Control means for controlling to switch to the communication system, and when the detection means detects that the radar system is being used, communication in the wireless communication system is continued on the second communication channel. It is characterized by that.

  According to the present invention, it takes almost 60 seconds after an operation to start communication based on ETSI EN 301 893v1.2.2 without taking more than 60 seconds for radar detection before starting data communication. Communication can be started without having time.

Hereinafter, a wireless communication method and apparatus according to embodiments of the present invention will be described in detail with reference to the drawings.
(First embodiment)
An example of a specific configuration of the wireless communication apparatus according to the present embodiment will be described with reference to FIG. FIG. 1 is a block diagram of a wireless communication apparatus 10 according to the first embodiment of the present invention.
The wireless communication device 10 has two wireless units, and can perform data communication on the one hand and perform radar detection on the other hand, and simultaneously perform radar detection while performing data communication. As shown in FIG. 1, the wireless communication device 10 includes a first wireless unit 11, a modem unit 12, a second wireless unit 13, a radar detection unit 14, a channel switching unit 15, a channel selection unit 16, and a radar detection necessity determination unit. 17, a control unit 18, and a channel information storage unit 19.

  The first radio unit 11 enables a wireless LAN system using multi-carrier radio transmission (OFDM), and transmits and receives signals in a format as shown in FIG. This signal includes a preamble, a guard interval, and a data symbol, and the preamble is used for synchronization by detecting the head position of the signal. The guard interval is for suppressing intersymbol interference that may occur between adjacent symbols. Data symbols contain information that is to be transmitted. The modem unit 12 demodulates the signal received by the first radio unit 11 and modulates the signal that the first radio unit 11 is about to transmit.

  The second radio unit 13 is for radar detection, and tries to receive a radar pulse emitted by the radar transmitter in the designated channel. The radar detection unit 14 determines whether or not the signal received by the second radio unit 13 is a radar pulse and detects the presence of radar in the designated channel.

  The channel switching unit 15 switches the channel used by the wireless communication device 10. There are a plurality of channels that the wireless communication apparatus 10 can use in the wireless LAN system. For example, as shown in FIG. 3, three channels are included in each of three frequency bands. The channel switching unit 15 switches between these channels. The channel selection unit 16 selects channels uniformly so as not to make a biased selection to a certain channel as in European regulations. For example, the channel selection unit 16 randomly selects from all available channels (9 types of Ch1 to Ch9 in the example of FIG. 3) using random numbers. As another example, the channel selection unit 16 may accumulate the statistical data for the channels used so far, and select the channels based on the statistical data so that the usage rates of all the channels are averaged.

The radar detection necessity determination unit 17 determines whether the channel selected by the channel selection unit 16 requires radar detection. Specifically, for example, when the channel selection unit 16 selects Ch5 shown in FIG. 3, the radar detection necessity determination unit 17 determines that radar detection is necessary, and the second radio unit 13 and the radar detection unit 14 attempts radar detection.
Channels that can be used in the wireless LAN system may include frequency bands used for radar as shown in FIG. In the example of FIG. 3, the radar may be used in frequency bands from 5.25 GHz to 5.35 GHz and from 5.47 GHz to 5.725 GHz. Therefore, when the channel selection unit 16 selects a channel within this frequency band, the second radio unit 13 and the radar detection unit 14 attempt radar detection. Since the other frequency bands from 5.15 GHz to 5.25 GHz are for indoor use, when the channel selection unit 16 selects channels in these frequency bands, it is not necessary to perform radar detection.
The channel information storage unit 19 stores channel information indicating the frequency band in which the channel is included, the type of channel included in this frequency band, whether or not this frequency band requires radar detection, and the like. The channel information is the information shown in FIG. 3, for example.

  The control unit 18 is for controlling the operation of each unit of the wireless communication device 10. For example, the channel selected by the channel selection unit 16 is passed to the channel switching unit 15 and the radar detection necessity determination unit 17, or radar detection is performed. Based on the result determined by the necessity determination unit 17, a command for radar detection is output to the second radio unit 13 and the radar detection unit 14. The control unit 18 also controls an example of the next operation described with reference to FIG.

Next, an example of a specific operation of the wireless communication device 10 will be described with reference to the flowchart of FIG.
First, the power source of the wireless communication device 10 is turned on (step S11), and the channel used by the channel selection unit 16 for communication from now on is randomly selected from the channel information stored in the channel information storage unit 19, for example. (Step S12). Based on the channel information, the radar detection necessity determination unit 17 determines whether or not the selected channel is a channel that requires radar detection (step S13). When the selected channel requires radar detection (for example, when Ch5 is selected), the process proceeds to step S15. On the other hand, when the selected channel does not need radar detection (for example, when Ch1 is selected). Advances to step S14. In step S14, communication is started on the channel selected in step S12. That is, the first radio unit 11 starts transmission / reception of a signal having the format shown in FIG. 2 on the selected channel.

  In step S15, the control unit 18 selects a channel that does not require radar detection from the channel information, and starts communication using this channel. Specifically, for example, communication is started at Ch3 that does not require radar detection shown in FIG. This channel may be selected from a frequency band that does not require radar detection. For example, the control unit 18 randomly selects a channel from this frequency band. In addition, communication is started, and the second radio unit 13 and the radar detection unit 14 start radar detection on the channel selected in step S12 (step S16). In the ETSI EN 301 893v1.2.2 standard, it is necessary to spend more than 60 seconds for radar detection, so step S16 requires 60 seconds or more according to this standard.

  The radar detector 14 determines whether or not the signal received by the second radio unit 13 is a radar pulse (step S17). If the received signal is a radar pulse, the process proceeds to step S18. If the received signal is not a radar pulse, the process proceeds to step S19. In step S18, communication is continued on the channel that does not require radar detection, which started communication in step S15. In step S19, since it is confirmed that the channel selected in step S12 is not used by the radar, the channel switching unit 15 switches to the channel selected in step S12, and communication is continued on this channel (step S20). ). The channel switching unit 15 does not switch the channel immediately after detecting the radar and confirming that there is no radar signal, but switches the channel while the currently communicating application is paused, When the TV channel is changed, the channel may be switched in synchronization. In addition, the channel switching unit 15 may switch channels between CMs if the user is receiving TV broadcasts.

  As described above, since the wireless communication apparatus according to the present embodiment includes the wireless unit for data communication and the wireless unit for radar detection separately, radar detection can be performed in the background while performing data communication. it can. Therefore, it does not take more than 60 seconds for radar detection before starting data communication, and has almost a waiting time after operating to start communication based on ETSI EN 301 893v1.2.2. Communication can be started. Further, as described above, if a channel is randomly selected from the channel information in step S12 or if a channel is selected based on statistical data, all frequency bands that can be used without being biased to a specific frequency band are used. The included channels can be used on average.

(Second Embodiment)
An example of a specific configuration of the wireless communication apparatus according to the present embodiment will be described with reference to FIG. FIG. 5 is a block diagram of the wireless communication device 20 according to the second embodiment of the present invention.
Although the radio communication device 20 has only one radio unit, radar detection is performed using an idle (IDLE) time, which is a time during which data communication is interrupted, so that a large amount of time is detected at the start of communication. Can be spent on. The wireless communication device 20 of the present embodiment is different from the wireless communication device 10 of the first embodiment in that there is only one wireless unit. Therefore, hereinafter, the same parts as those of the wireless communication apparatus 10 of the first embodiment are denoted by the same reference numerals and description thereof is omitted. As shown in FIG. 5, the radio communication device 20 includes a radio unit 21, a modem unit 12, a radar detection unit 14, a channel switching unit 15, a channel selection unit 16, a radar detection necessity determination unit 17, a control unit 28, and a channel. It consists of an information storage unit 19.

  The wireless unit 21 has the functions of the first wireless unit 11 and the second wireless unit 13 of the first embodiment. In other words, data communication by a wireless LAN system using multi-carrier wireless transmission is realized, and a radar pulse emitted by a radar transmitter is received on the designated channel. The difference from the first embodiment is that the present embodiment has only one radio unit (only the radio unit 21), and therefore cannot perform radar detection in the background while performing data communication.

  The control unit 28 controls the operation of each unit of the wireless communication device 20 as in the first embodiment, but the control content is different. The control unit 28 predicts an idle time when data communication is interrupted, and performs control to execute radar detection during the idle time. For example, as shown in FIG. 6, the idle time may exist as IDLE time T1 and IDLE time T2 in the data communication of the wireless LAN system. When the control unit 28 determines that the idle time can be secured for a predetermined time or more (60 seconds or more according to ETSI EN 301 893v1.2.2), the radio unit 21 and the radar detection are performed during the idle time. If the radar pulse is present by controlling the unit 14, the radar pulse can be detected. The radar pulse detection operation is preferably performed using the radio unit 21 and the radar detection unit 14 at the same time as the idle time starts.

  Further, if the predetermined time cannot be easily secured by only one idle time (for example, IDLE time T1 in FIG. 6), each idle time can be determined if the total idle time generated during a certain period is not less than the predetermined time. It is possible to perform radar detection by performing a radar pulse detection operation in time. That is, radar detection is started from the first idle time, and radar detection is performed in the second idle time in a range not scanned in the first idle time. However, the range not scanned here is, for example, a case where 1 minute is required for the radar check. When the check time at the first idle time is 40 seconds, 60 × N seconds from the end of the measurement. It means the next 20 seconds (N is a natural number). If radar detection is executed in this way, the entire range around the wireless communication apparatus of the present embodiment can be scanned, so that it can be detected if a radar pulse is present.

  In the above, as shown in FIG. 6, the radar detection is performed using the time when the data communication is interrupted. It can also be performed when it can be determined that the data is unnecessary. For example, when the user receives audio / visual information, CM information is an example of typical unnecessary data. In this case, it is detected whether it is a CM, and radar detection is performed when the CM is reached. Further, if reception information indicating when CM information is received is known in advance, radar detection can be systematically performed using this reception information. The control unit 28 also controls an example of the next operation described with reference to FIG.

Next, an example of a specific operation of the wireless communication device 20 will be described with reference to the flowchart of FIG. Here, the same steps as those in the flowchart of FIG. 4 described in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.
First, the wireless communication device 20 performs the same operation from step S11 to step S15 in FIG. 4, and in step S15, the control unit 28 selects a channel that does not require radar detection from the channel information, and starts communication on this channel. To do. Then, it is determined whether or not the control unit 28 can secure a communication idle time or a reception time for receiving unnecessary communication data for a predetermined time (60 seconds according to ETSI EN 301 893 v1.2.2) or more. (Step S26). That is, the control unit 28 determines whether or not there is a time in which the idle time or unnecessary data reception time is equal to or longer than the predetermined time in the future from this determination time point. This determination is desirably performed periodically or systematically. If it is determined that an idle time of a predetermined time or more can be secured, the process proceeds to step S27. On the other hand, if it is determined that an idle time of a predetermined time or more cannot be secured, the process proceeds to step S18. In step S18, communication is continued on the channel that started communication in step S15.

  In step S27, the channel selection unit 16 switches to the channel selected in step S12, and the radar detection unit 14 determines whether the signal received by the wireless unit 21 is a radar pulse (step S17). If the received signal is a radar pulse, the process proceeds to step S28. If the received signal is not a radar pulse, the process proceeds to step S20. In step S28, the channel is switched to the channel that started communication in step S15, and communication is continued on this channel (step S18).

  As described above, since the wireless communication apparatus according to the present embodiment performs data communication and radar detection with a single wireless unit, it cannot perform radar detection in the background while performing data communication, but it does not perform data communication. By performing radar detection using a time unnecessary for the user or the user, the communication is started with little waiting time after the operation to start the communication based on ETSI EN 301 893v1.2.2. be able to.

(Third embodiment)
An example of a specific configuration of the wireless communication apparatus according to the present embodiment will be described with reference to FIG. FIG. 8 is a block diagram of a radio communication device 30 according to the third embodiment of the present invention.
The wireless communication device 30 of the present embodiment is the same as the wireless communication device 10 of the first embodiment, but is modified so that the first wireless unit 11 and the modem unit 12 can communicate with two types of modulation schemes. Further, instead of the modem unit 12, a radio unit 31, a first modem unit 12, and a second modem unit 32 are newly provided. Therefore, hereinafter, the same parts as those of the wireless communication apparatus 10 of the first embodiment are denoted by the same reference numerals and description thereof is omitted. As illustrated in FIG. 8, the wireless communication device 30 includes a first wireless unit 31, a first modem unit 12 (same configuration as the modem unit 12 of the first embodiment), a second modem unit 32, and a second wireless unit 13. , A radar detection unit 14, a channel switching unit 15, a channel selection unit 16, a radar detection necessity determination unit 17, a control unit 38, and a channel information storage unit 39.

The radio unit 31 is a radio unit for enabling transmission / reception of two radio systems. For example, wireless communication of both the OFDM system and SS (Spread Spectrum) system is realized. The first modem unit 12 modulates and demodulates a signal corresponding to, for example, the OFDM system.
The second modem unit 32 modulates and demodulates a signal corresponding to a communication method different from that of the first modem unit 12. Here, the second modem unit 32 performs modulation and demodulation of a signal corresponding to, for example, the SS system.

  The control unit 38 is different from the control unit 18 of the first embodiment in that the communication method for communication is changed and control for executing the operation described in the first embodiment is performed. That is, when usable channels exist in a plurality of different bands (for example, the 5 GHz band and the 2 GHz band shown in FIG. 9), not only the 5 GHz band but also the 2 GHz band is selected when a channel that does not require radar detection is selected. Use. For example, in addition to including the 2 GHz band among the channels selected in step S12, control is performed such that communication is first started in the 2 GHz band as a channel that does not require radar detection in step S15. In this embodiment, since it is assumed that the communication method used in each band is different, the control unit 38 uses the first modulation / demodulation unit 12 and the first modulation / demodulation unit 12 so that different modulation / demodulation units are used in each band of 5 GHz band and 2 GHz band. 2 Instructs the modem unit 32.

  The channel information storage unit 39 has the same configuration as the channel information storage unit 19 of the above embodiment, and the frequency band in which the channel is included, the type of channel included in this frequency band, and whether or not this frequency band requires radar detection. However, the stored channel information includes not only the channel shown in FIG. 3 but also 2 GHz band information as shown in FIG.

  In the above example, different modulation / demodulation units are used in the 5 GHz band and the 2 GHz band, but the same is used when the radio unit uses the same communication method in both the 2 GHz band and the 5 GHz band. It is also possible to cope with this modem unit.

  As described above, since the wireless communication apparatus according to the present embodiment can communicate with many channels that do not require radar detection, it is easy to find a channel for data communication, and it is necessary to detect radar before data communication is started. The communication can be started with almost no waiting time after the operation to start the communication based on the ETSI EN 301 893 v1.2.2 without taking a time longer than a second.

  In addition, the instructions shown in the processing procedure shown in the above-described embodiment and the instructions shown in each step of the flowchart can be executed based on a program that is software. The general-purpose computer system stores this program in advance and reads this program, so that the same effect as that obtained by the wireless communication apparatus according to the above-described embodiment can be obtained. The instructions described in the above-described embodiments are, as programs that can be executed by a computer, magnetic disks (flexible disks, hard disks, etc.), optical disks (CD-ROM, CD-R, CD-RW, DVD-ROM, DVD). ± R, DVD ± RW, etc.), semiconductor memory, or a similar recording medium. If the computer reads the program from the recording medium and causes the CPU to execute instructions described in the program based on the program, the same operation as that of the wireless communication apparatus of the above-described embodiment can be realized.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

1 is a block diagram of a wireless communication apparatus according to a first embodiment of the present invention. The figure which showed the format of the signal which the radio | wireless communication apparatus of FIG. 1 transmits / receives. The figure which showed the channel information which the channel information storage part of FIG. 1 has stored. 3 is a flowchart showing an example of an operation performed by the wireless communication apparatus of FIG. The block diagram of the radio | wireless communication apparatus which concerns on the 2nd Embodiment of this invention. The figure for demonstrating the idle time generate | occur | produced during the data communication by the radio | wireless communication apparatus of FIG. 6 is a flowchart showing an example of an operation performed by the wireless communication apparatus of FIG. The block diagram of the radio | wireless communication apparatus which concerns on the 3rd Embodiment of this invention. The figure which showed the channel information which the channel information storage part of FIG. 8 has stored.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Wireless communication apparatus, 11 ... 1st radio | wireless part, 12 ... Modulator / demodulator, 13 ... 2nd radio | wireless part, 14 ... Radar detection part, 15 ... Channel switching part, 16 ... Channel selection unit, 17 ... Radar detection necessity determination unit, 18 ... Control unit, 19 ... Channel information storage unit, 20 ... Wireless communication device, 21 ... Radio unit, 28 ... Control unit, 30 ... Wireless communication device, 31 ... Radio unit, 32 ... Second modem unit, 38 ... Control unit, 39 ... Channel information storage unit

Claims (3)

Storing first information indicating at least one first communication channel usable in the radar system and second information indicating at least one second communication channel not usable in the radar system;
When communicating with a certain wireless communication system, one third communication channel is randomly selected from a plurality of communication channels including at least one of the first communication channels and the second communication channel,
Referring to the first information, determining whether it is necessary to detect whether or not the signal received in the selected third communication channel is currently used in a radar system;
When it is determined that it is necessary to detect, control to start communication in the wireless communication system on the second communication channel,
Detecting whether the signal received in the third communication channel is currently used in a radar system;
If it is detected that it is not used in the radar system, control to switch communication in the wireless communication system to the third communication channel,
A wireless communication method characterized in that communication in the wireless communication system is continued on the second communication channel when it is detected that the radar system is being used.   Storing first information indicating at least one first communication channel usable in the radar system and second information indicating at least one second communication channel not usable in the radar system;
  When communicating with a certain wireless communication system, one third communication channel is randomly selected from a plurality of communication channels including at least one of the first communication channels and the second communication channel,
  Referring to the first information and determining whether the selected third communication channel matches any of the first communication channels;
  Detecting whether the signal received on the third communication channel is currently used in a radar system;
  When it is determined to match, control to start communication in the wireless communication system on the second communication channel,
  If it is detected that it is not used in the radar system, control to switch communication in the wireless communication system to the third communication channel,
  A wireless communication method characterized in that communication in the wireless communication system is continued on the second communication channel when it is detected that the radar system is being used.   Storage means for storing first information indicating at least one first communication channel usable in the radar system and second information indicating at least one second communication channel not usable in the radar system;
  Selection means for randomly selecting one third communication channel from a plurality of communication channels including at least one of the first communication channels and the second communication channel when communicating in a wireless communication system;
  A determination unit that refers to the first information of the storage unit and determines whether or not the third communication channel selected by the selection unit matches any of the first communication channels;
  Detecting means for detecting whether a signal received on the third communication channel is currently used in a radar system;
  When it is determined by the determination means that they match, the communication in the wireless communication system is controlled to start on the second communication channel, and when the detection means detects that the radar system is not used. Comprises control means for controlling to switch communication in the wireless communication system to the third communication channel,
  The wireless communication apparatus according to claim 1, wherein when the detection means detects that the radar system is being used, communication in the wireless communication system is continued on the second communication channel.

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