JP2009212967A - Radio communication apparatus, control method for the radio communication apparatus, and control program for the radio communication apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent occurrence of a phenomenon that a frame is disabled from normally arriving at a radio communication apparatus of a communication partner, because of a narrow communicable range caused by increasing the number of radio channels to be used simultaneously for transmission. <P>SOLUTION: A radio base station AP1 comprises: a receiving means 42 for receiving a first signal from a first radio terminal; a setting means 45 for setting the number of radio channels to be used simultaneously for transmitting a radio signal, so that a distance that a radio signal transmitted by the present radio base station can achieve, becomes greater than an estimation result of a distance, between the present radio base station and the first radio terminal, estimated according to the first signal; and a transmitting means 41 for transmitting signals different for the radio channels, while simultaneously using the radio channels which are fewer than or equal to the number of radio channels set by the setting means, or transmitting to the first radio terminal the same signal for the radio channels, while simultaneously using the radio channels more than the number of radio channels set by the setting means. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

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

  In recent years, the spread of a wireless LAN (Local Area Network) system compliant with the IEEE802.11 standard used as a radio channel every 20 MHz in the 2.4 GHz band and the 5 GHz band has been accelerated.

  The IEEE802.11a / b / g standard is a method of performing wireless communication using one wireless channel having a frequency bandwidth of 20 MHz. However, in Task Group n (TGn) that promotes standardization of the IEEE802.11n standard, it is 100 Mbps or more. In order to achieve the above-mentioned throughput, a technique for simultaneously using two adjacent radio channels having a frequency bandwidth of 20 MHz is being studied.

Under such circumstances, for example, a technique for selecting a radio channel to be used simultaneously from a group of available radio channels has been proposed (for example, Patent Document 1).
JP 2007-96786 A

  In the IEEE 802.11 standardization conference, as a Study Group, a technique for realizing a speed higher than the throughput that TGn exceeds the target has begun to be studied. For example, a method for increasing the number of radio channels used simultaneously is being studied. Yes.

  However, since the current IEEE802.11-compliant wireless communication apparatus keeps the total transmission power of a plurality of wireless channels constant, the transmission power of each wireless channel is inversely proportional to the increase in the number of wireless channels used during transmission. Will decrease.

  Even if the total transmission power of a plurality of radio channels is not constant, the transmission power of each radio channel increases as the number of radio channels used at the time of transmission increases in consideration of a request for power saving to the radio communication device. It is inevitable that there will be a decrease.

  Therefore, by increasing the number of radio channels used by a certain radio communication device during transmission, the transmission power of each radio channel is reduced and the communicable range is narrowed. There arises a problem that the communication partner that has been placed is located outside the communicable range.

  For example, if a local wireless communication device that has received a frame from another wireless communication device increases the number of wireless channels used simultaneously and returns a response frame, the wireless communication device may not reach the other wireless communication device. In such a case, the other wireless communication device determines that the transmission of the frame has failed, and performs retransmission. However, the response frame from the own wireless communication device does not reduce the other wireless channel unless the number of wireless channels used at the same time is reduced. The communication device will not be reached, and wireless communication will continue to fail.

  In addition, for example, when the number of wireless channels used at the time of transmission is smaller than that of the own wireless communication device, the communicable range of the other wireless communication device is greater than the communicable range of the own wireless communication device. Become wider. For this reason, other wireless communication devices cannot receive radio waves transmitted by their own wireless communication devices, but their own wireless communication devices can receive radio waves transmitted by other wireless communication devices. In such a case, even if the own wireless communication device is transmitting and receiving frames, other wireless communication devices are not aware of it, so frames may be transmitted continuously and frame collisions may occur frequently. There is sex. At this time, the self wireless communication device corresponds to a hidden terminal for other wireless communication devices.

  The present invention has been made to solve the above-described problems of the prior art, and since the number of radio channels simultaneously used for transmission is increased, the communicable range is narrowed and the radio communication apparatus of the communication partner An object of the present invention is to provide a wireless communication apparatus, a wireless communication apparatus control method, and a wireless communication apparatus control program that can prevent the occurrence of a phenomenon in which a frame does not reach normally.

  In order to achieve the above object, a wireless communication device according to an embodiment of the present invention is a wireless communication device that performs wireless communication using a plurality of wireless channels, and receives a first signal from the first wireless communication device. A receiving unit configured to perform reception, a reachable distance of the wireless signal determined for each number of wireless channels used simultaneously when transmitting the wireless signal, and the first wireless communication apparatus and the first wireless communication device, wherein the reachable distance of the wireless signal is estimated according to the first signal Setting means for setting the number of radio channels used simultaneously when transmitting a radio signal so as to be larger than the estimation result of the distance to the radio communication device; and a radio having a radio channel number equal to or less than the number of radio channels set by the setting means Use a channel to transmit a different signal on each radio channel, or use more radio channels than the number of radio channels set by the setting means, Characterized in that it comprises a transmitting means for transmitting a control signal indicating the period to use other manner radio channel.

  According to the present invention, since the number of radio channels simultaneously used for transmission is increased, it is possible to prevent a phenomenon in which a communicable range is narrowed and a frame does not normally reach a communication partner radio communication device. it can.

  Hereinafter, embodiments of the present invention will be described.

(First embodiment)
FIG. 1 is a diagram showing a radio system according to the first embodiment of the present invention. The wireless system includes a wireless base station AP1, which is an access point, a wireless terminal A, and a wireless terminal B. The radio base station AP1 and the radio terminals A and B communicate using a plurality of radio channels. The wireless system according to the first embodiment is compliant with the IEEE 802.11 standard.

  When the radio base station AP1 uses one radio channel (the number of channels used) at the time of transmission, the reachable radio signal is 85 m, which is indicated by a broken line in FIG. When the wireless base station AP1 uses two channels, the distance that the wireless signal can reach is 70 m, which is indicated by a dashed line in FIG. When the radio base station AP1 transmits three different radio signals using three radio channels, the reachable distance of the radio signal is 63 m, which is indicated by a solid line in FIG. The reachable distance of the radio signal transmitted by the radio base station AP1 is calculated based on the channel model “path loss” used in TGn.

  Even if the wireless base station AP1 uses three channels, the wireless terminal A is located within the range where the wireless signal reaches. The radio terminal B is located in a range where the radio signal arrives when the number of used channels of the radio base station AP1 is one, but does not reach when the number of used channels is two.

FIG. 2 is a block diagram showing a configuration of the radio base station AP1.
The radio base station AP1 includes a radio unit 20, a modem unit 30, and a MAC (Media Access Control) processing unit. The modem unit 30 includes a modulation unit 31, a demodulation unit 32, and a carrier sense unit 33. The MAC processing unit 40 includes a transmission unit 41-3, a reception unit 42, a MAC control unit 43, a memory 44, a channel number setting unit 45, and a carrier sense control unit 46.

  First, an outline of an operation when the radio base station AP1 transmits a frame will be described below. The upper layer processing unit outputs data to be transmitted to the transmission unit 41-3. The transmission unit 41-3 performs processing related to the MAC layer such as adding a MAC header to the data. The transmission unit 41-3 accumulates data subjected to processing related to the MAC layer in a transmission queue (not shown) built in as a frame. The transmission queue outputs frames to the modulation unit 31 in the order in which they are accumulated in the transmission queue. The modulation unit 31 performs processing related to the physical layer such as processing for adding a physical header to a frame, encoding processing, and modulation processing. The modulation unit 31 outputs the frame subjected to the processing related to the physical layer to the radio unit 20. The radio unit 20 performs D / A (Digital to Analog) conversion processing on the frame, performs frequency conversion to a frequency band of radio communication, and performs transmission processing via the antenna 10.

  The memory 44 stores the reachable distance of the radio signal corresponding to the number of used channels for each number of used channels in the radio base station AP1. The memory 44 stores the estimation result of the distance between the wireless signal transmission source (or transmission destination) and the wireless base station AP1 in association with the received signal strength of the wireless signal and the number of used channels. For example, the memory 44 transmits the radio signal in association with the received signal strength of the radio signal received by the radio base station AP1 and the number of radio channels simultaneously used when the radio signal is transmitted. The estimation result of the distance between the transmission source (for example, the wireless terminal A) and the wireless base station AP1 is stored. Further, for example, the memory 44 stores the received signal strength when the radio signal transmitted by the radio base station AP1 is received at the transmission destination (for example, the radio terminal A) and the radio channel used simultaneously when the radio signal is transmitted. Is stored in association with the number of radio base stations AP1 and the radio signal transmission destination (for example, radio terminal A).

  Next, an outline of an operation when the radio base station AP1 receives a frame will be described below. A radio signal received by the antenna 10 is input to the radio unit 20. The radio unit 20 performs frequency conversion processing on the radio signal to baseband, then performs A / D (Analog to Digital) conversion processing, and outputs the result to the demodulation unit 32. The demodulator 32 performs a process such as a demodulation process and a physical header analysis, and outputs the received frame to the MAC processor 40. The demodulator 32 notifies the received signal strength (RSSI: Received Signal Strength Indicator) of the received radio signal to the carrier sense unit 33. The receiving unit 42 of the MAC processing unit 40 analyzes the MAC header and outputs data to the upper layer processing unit when the received frame is addressed to the radio base station AP1.

  Here, the receiving unit 42 of the MAC processing unit 40 determines whether the received frame is an association request signal for requesting connection to the radio base station AP1, or a radio channel (standby for which the connected radio terminal is in a standby state). In the case of the standby channel change signal for notifying that the (channel) is to be changed, the fact that the number of used channels needs to be set anew is output to the channel number setting unit 45.

  Next, when the number-of-channels setting unit 45 receives that the number of used channels needs to be set anew, it sets the number of used channels by a predetermined process. Details of how the channel number setting unit 45 sets the number of used channels will be described later.

  Next, the channel number setting unit 45 outputs the set number of used channels to the carrier sense control unit 46. The carrier sense control unit 46 specifies a radio channel for performing carrier sense using information such as the number of used channels. The carrier sense unit 33 performs carrier sense of the radio channel specified by the carrier sense control unit 46. Note that details of a method by which the carrier sense control unit 46 specifies a radio channel for performing carrier sense will be described later.

  Further, the receiving unit 42 of the MAC processing unit 40 receives information about a standby channel of a wireless terminal newly connected to the wireless base station AP1 by an association request signal or a wireless device connected to the wireless base station AP1 by a standby channel change signal. Information about the standby channel of the terminal (standby channel information) is output to the MAC control unit 43.

  Next, the MAC control unit 43 writes standby channel information for each wireless terminal in the memory 44. Whether or not the MAC control unit 43 writes the standby channel information in the memory 44 depends on whether or not the connection to the association request signal is possible, whether or not the standby channel can be changed in response to the standby channel change signal, and the number of channels used by the channel number setting unit 45 Depends on the setting result.

  The wireless base station AP1 performs the process of storing the standby channel information of the wireless terminal in the memory 44. However, the wireless terminal conforming to the IEEE802.11a / b / g standard also uses the standby channel. Therefore, there is no need to notify the standby channel information and no change is required.

  The wireless terminal conforming to the IEEE 802.11n standard uses one or two channels, and the memory 44 needs to store standby channel information of the wireless terminal conforming to the IEEE 802.11n standard. Here, in the association request signal in the IEEE 802.11n standard, information indicating whether the transmission source wireless terminal supports only one wireless channel or two wireless channels is HT Capability element. In the Supported Channel Width. Therefore, the standby channel information of the wireless terminal compliant with the IEEE 802.11n standard can be stored in the memory 44 based on the above information.

  Furthermore, not only the already established standards but also the wireless terminals that comply with newly established standards in the future, the newly established standards, the number of the wireless channel that the wireless terminal is in the standby state, and the wireless terminals If there is a mechanism for notifying the radio base station AP1 of the number of radio channels in the standby state, a process of storing the standby channel information of the radio terminal connected to the radio base station AP1 in the memory 44 can be realized.

  FIG. 3 is a flowchart showing an operation when the channel number setting unit 45 sets the number of used channels. It is assumed that the radio base station AP1 and the radio terminal A are connected, and the radio terminal B transmits an association request signal to the radio base station AP1.

  First, the radio base station AP1 receives a specific signal (trigger signal) from a connected wireless terminal or a wireless terminal that newly requests a connection (step S101). When the radio base station AP1 receives a trigger signal (association request signal) from the radio terminal B, the channel number setting unit 45 is notified of this, and the channel number setting unit 45 starts processing for setting the number of used channels. . The same applies when the radio base station AP1 receives a trigger signal (channel number change signal) from the radio terminal A.

  The trigger signal is a signal for requesting a new connection to the radio base station AP1 or a signal for changing the number of channels used when performing radio communication with the radio base station AP1. In the present embodiment, the trigger signal is an association request signal or a channel change signal.

  Next, the channel number setting unit 45 of the radio base station AP1 estimates the distance between the radio base station AP1 and the radio terminal B (step S102). The channel number setting unit 45 has two methods for estimating the distance between the radio base station AP1 and the radio terminal B.

  The first method is based on the received signal strength of the radio signal received by the radio base station AP1 from the radio terminal B and the number of channels used when the radio terminal B transmits the radio signal to the radio base station AP1. In this method, the distance between the base station AP1 and the wireless terminal B is estimated.

  The received signal strength of the radio signal received by the radio base station AP1 from the radio terminal B is, for example, the received signal strength when the radio base station AP1 receives the association request signal from the radio terminal B. The information on the received signal strength may be notified from the demodulator 32 to the channel number setting unit 45 via the carrier sense unit 33 or to the channel number setting unit 45 via the receiving unit 42. Also good.

  The number of channels used when the wireless terminal B transmits a wireless signal to the wireless base station AP1 may be described in the wireless signal transmitted by the wireless terminal B, and when the wireless terminal B connects to the wireless base station AP1. It may be set in advance.

  In this way, the channel number setting unit 45 uses the received signal strength of the radio signal received by the radio base station AP1 from the radio terminal B and the number of channels used when the radio terminal B transmits the radio signal to the radio base station AP1. And get. The channel number setting unit 45 uses the received signal strength of the wireless signal and the number of used channels acquired as described above, and the distance between the wireless signal transmission source (wireless terminal B) and the wireless base station AP1 from the memory 44. Read the estimation result of.

  The second method is based on the received signal strength of the radio signal received by the radio terminal B from the radio base station AP1 and the number of channels used when the radio base station AP1 transmits the radio signal to the radio terminal B. In this method, the distance between the base station AP1 and the wireless terminal B is estimated.

  The received signal strength of the wireless signal received by the wireless terminal B from the wireless base station AP1 is, for example, a signal for allowing the wireless base station AP1 to notify the wireless terminal B of the received signal strength, such as TPC Request frame of IEEE802.11h. Then, the received signal strength when the signal is received can be acquired by returning the wireless terminal B to the response.

  The number of channels used when the wireless base station AP1 transmits a wireless signal to the wireless terminal B is the number of wireless channels used when transmitting a signal for notifying the wireless terminal B of the received signal strength. By storing it, the channel number setting unit 45 can read it out when setting the number of used channels.

  In this way, the channel number setting unit 45 uses the received signal strength of the radio signal received by the radio terminal B from the radio base station AP1 and the number of channels used when the radio base station AP1 transmits the radio signal to the radio terminal B. And get. The channel number setting unit 45 uses the received signal strength of the radio signal and the number of used channels acquired as described above, and the distance between the radio base station AP1 and the radio signal transmission destination (radio terminal B) from the memory 44. Read the estimation result of.

  Next, the channel number setting unit 45 initializes the dummy variable X to 1 (step S103).

  Next, the channel number setting unit 45 sets the wireless signal reachable distance when the number of used channels is 1 (the value of “X” when X = 1) and the number of used channels when 2 (X = 1). (X + 1) of the radio signal) and the estimation result of the distance between the radio base station AP1 and the radio terminal B (estimation result in step S102) are compared (step S104). ). The channel number setting unit 45 reads from the memory 44 the reach of the radio signal when the number of used channels is “X” or “X + 1”.

  The estimation result of the distance between the radio base station AP1 and the radio terminal B is larger than the reach of the radio signal when the number of used channels is 2 (value of “X + 1” when X = 1), and the radio base station When the reach of the radio signal is larger than the estimated result of the distance between the station AP1 and the radio terminal B when the number of channels used is 1 (the value of “X” when X = 1) (“Yes” in step S104) ”), The channel number setting unit 45 sets the number of used channels to the current dummy variable value“ X ”(here, X = 1) (step S105).

  In step S105, the number of used channels is “X” for all connected wireless terminals (in this case, only the wireless terminal A) (the number of used channels set in response to the association request of the wireless terminal B is X = 1). However, the number of channels used may be set to “X + 1” for a wireless terminal other than the wireless terminal that transmitted the trigger signal in step S101 (here, wireless terminal A). At this time, the same control frame for exclusively using the “X + 1” used channels is transmitted using “X + 1” used channels called “Duplicate frames” (hereinafter referred to as “transmitted as Duplicate frames”). On the condition that transmission is performed (protection is performed) through “X + 1” radio channels.

  On the other hand, when the condition specified in step S104 is not satisfied (“No” in step S104), the channel number setting unit 45 increases the value of the dummy variable X by one (step S106).

  Next, the channel number setting unit 45 determines whether or not the value of the dummy variable X is less than the upper limit value (step S107). The upper limit value is the minimum value among the following three values.

  The first value is the maximum number of radio channels that can be used simultaneously when the radio base station AP1 transmits radio signals. The second value is the number of radio channels (the number of standby channels) in which the trigger signal source or the connected wireless terminals (in this case, the wireless terminals A and B) are in a standby state. The third value is the number of used channels previously set by the channel number setting unit 45 when a trigger signal is received from another wireless terminal, and is the number of used channels for the currently connected wireless terminal A. Is the minimum value.

  When the value of the dummy variable is less than the upper limit value (“Yes” in step S107), the channel number setting unit 45 performs the process of step S104 again.

  On the other hand, when the value of the dummy variable is greater than or equal to the upper limit value (“No” in step S107), the channel number setting unit 45 sets the number of used channels to “upper limit value” (step S108).

  FIG. 4 is a flowchart showing an operation when the carrier sense control unit 46 specifies a radio channel for performing carrier sense according to the number of used channels set by the channel number setting unit 45.

  FIG. 5 shows an example of a radio channel used by the radio base station AP1. In the example shown in FIG. 5A, the wireless channels Ch3 and Ch4 are already used in another BSS (Basic Service Set). In the example shown in FIG. 5B, the wireless channels Ch3, Ch4, and Ch6 are used. Are already used in other BSSs.

  First, the number of used channels set by the channel number setting unit 45 is input to the carrier sense control unit 46 (step S201). The carrier sense control unit 46 starts processing for determining a radio channel for starting carrier sense, triggered by the input of the number of used channels.

  Next, the carrier sense control unit 46 includes all radio channel numbers (channel candidate numbers) that can be used by the radio base station AP1 and radio channel numbers (other BSS use channel numbers) used by other BSSs. Is read from the memory 44 (step S202). The channel candidate number and the other BSS use channel number may be stored in a memory 44 (not shown) built in the carrier sense control unit 46.

  In addition, the channel number used by other BSS is specified by monitoring information (channel usage status) about which radio channel a radio base station or radio terminal belonging to another BSS is using. Is done. The other BSS use channel number is not limited to the above method, and may be specified by collecting information from the radio terminals A and B connected to the radio base station AP1 or collecting information from radio base stations and radio terminals belonging to the other BSS. good.

  Next, the carrier sense control unit 46 specifies a radio channel number that is not used by another BSS from the channel candidate number and the other BSS use channel number (step S203). For example, in the example shown in FIG. 5A, the channel candidate numbers are 1 to 8 and the other BSS use channel numbers are 3 and 4, so that the radio channel number that is not used by another BSS is the channel number 1 2, 5-7. In the example shown in FIG. 5 (b), the channel candidate numbers are 1 to 8 and the other BSS use channel numbers are 3, 4, and 6. Therefore, the radio channel numbers that are not used by other BSSs are channel numbers. Numbers 1, 2, 5, and 7 are used.

Next, the carrier sense control unit 46 determines whether or not radio channels that are not used by other BSSs continue for the number of used channels or more (step S204). For example, when the number of used channels is set to “3”, in the example shown in FIG. 5A, there are three radio channels (channel numbers 1, 2, 5 to 7) that are not used for other BSSs ( The number of used channels) is continuous ("Yes" in step S204). On the other hand, in the example shown in FIG. 5B, there are not three consecutive radio channels (channel numbers 1, 2, 5, and 7) that are not used for other BSSs (number of used channels) (in step S204). "No").

  When radio channels that are not used by other BSSs continue for more than the number of channels used ("Yes" in step S204), the carrier sense control unit 46 is a radio channel that is not used by other BSSs, It is assumed that carrier sense is started from radio channels that are continuous for the number of channels used.

  The carrier sense control unit 46 causes the carrier sense unit 33 to perform carrier sense for the radio channel for which carrier sense is to be started (step S205). For example, in the example illustrated in FIG. 5A, the carrier sense control unit 46 identifies the radio channels with channel numbers 5 to 7 as radio channels for performing carrier sense.

  Next, the carrier sense control unit 46 determines whether or not all carrier sense results of radio channels that are not used for other BSSs and that are continuous for the number of used channels are “idle” (IDLE). Determination is made (step S206).

When all the carrier sense results of radio channels that are not used by other BSSs and are continuous for the number of channels used are “free” (“Yes” in step S206), the carrier sense control unit 46 Sets the number of the wireless channel set as “free” as the used channel number (step S207).
On the other hand, if the carrier sense results of radio channels that are not used by other BSSs and are continuous for more than the number of channels used are not “free” (“No” in step S206), or When radio channels that are not used by other BSSs are not continuous more than the number of used channels (“No” in step S204), the channel number setting unit 45 selects radio channels that are not used by other BSSs. A radio channel for performing carrier sense is specified (step S208). The carrier sense control unit 46 causes the carrier sense unit 33 to perform carrier sense for the specified radio channel (step S209).

  For example, in the example shown in FIG. 5B, radio channels that are not used for other BSSs are not continuous more than the number of channels used, but the radio channels 1 and 2 are adjacent to each other. In order to make them adjacent to each other, the carrier sense control unit 46 identifies the radio channels 1, 2, 5 or the radio channels 1, 2, 7 as radio channels for performing carrier sense.

  Then, as a result of performing carrier sense, when it is determined that the number of used radio channels is “free”, the carrier sense control unit 46 sets the number of the used wireless channel as the used channel number. Is set (step S210).

  On the other hand, if the number of radio channels determined as “free” is less than the number of used channels as a result of carrier sense, the carrier sense control unit 46 determines that the number of used channels is “vacant”. Then, the carrier sense control unit 46 sets the number of the wireless channel determined as “available” as the used channel number (step S211). The number of used channels and the used channel number set by the carrier sense control unit 46 are stored in the memory 44 or a memory built in the carrier sense control unit 46.

  Thus, according to the radio base station according to the first embodiment, according to the magnitude relationship between the estimation result of the distance between the radio base station and the radio terminal and the reach of the radio signal according to the number of used channels. In order to set the number of channels used when transmitting radio signals, the radio signal does not reach the radio terminal due to a decrease in the reach of the radio signal as the number of channels used increases, and radio communication cannot be continued. And the occurrence of the hidden terminal problem can be suppressed.

  Furthermore, only the radio channel specified by the carrier sense control unit 46 is carrier sensed by the carrier sense unit 33, so that the number of radio channels for performing carrier sense can be reduced, and the power consumption required for carrier sense can be reduced. .

  Furthermore, when a plurality of (number of used channels) radio channels are secured, the carrier sense is preferentially performed on the adjacent radio channels, thereby increasing the possibility of securing the adjacent radio channels. Transmission efficiency can be improved.

  Regarding the radio base station according to the first embodiment, in the above, the memory 44 stores the reachable distance of the radio signal according to the number of used channels for each number of used channels in the radio base station AP1. The estimation result of the distance between the wireless signal transmission source (or transmission destination) and the wireless base station AP1 is stored in association with the received signal strength of the wireless signal and the number of channels used.

  However, the memory 44 may store the number of used channels in association with the received signal strength of the radio signal and the number of used channels.

  In the operation of setting the number of channels by the channel number setting unit 45 shown in FIG. 3 (steps S101 to S108), if the upper limit number is infinite, the received signal strength of the radio signal and the acquisition result of the number of used channels (step S102) ), The number of used channels is uniquely determined. For this reason, the number of used channels associated with the received signal strength of the radio signal and the number of used channels can be stored in advance in the memory 44.

  In this case, in step S102, the channel number setting unit 45 acquires the received signal strength and the number of used channels of the radio signal, and uses the stored number of used channels in association with the received signal strength of the radio signal and the used channel number. Read from the memory 44. Then, the channel number setting unit 45 confirms that the number of used channels read from the memory 44 is equal to or less than the upper limit value, and sets the number of used channels read from the memory 44 as a set value. When the number of used channels read from the memory 44 is larger than the upper limit value, the channel number setting unit 45 sets the upper limit value as the number of used channels.

  By doing in this way, the channel number setting part 45 can set the number of channels used, without performing the process of step S103-step S107.

  The radio base station AP1 can also be realized by using, for example, a general-purpose computer device as basic hardware. That is, the transmission unit 41-3, the reception unit 42, the MAC control unit 43, the channel number setting unit 45, and the carrier sense control unit 46 are realized by causing a processor mounted on the computer device to execute a program. Can do. At this time, the radio base station AP1 may be realized by installing the above program in a computer device in advance, or may be stored in a storage medium such as a CD-ROM or distributed via the network. Then, this program may be realized by appropriately installing it in a computer device. The memory 44 can be realized by appropriately using a memory, a hard disk or a storage medium such as a CD-R, a CD-RW, a DVD-RAM, a DVD-R, etc., which is built in or externally attached to the computer device. it can.

(Second Embodiment)
In the radio base station AP1 according to the first embodiment, a signal for requesting a new connection to the radio base station AP1 or a number of channels used for radio communication with the radio base station AP1 is changed. When a signal is received, the fact is notified to the channel number setting unit 45, and the channel number setting unit 45 starts processing for setting the number of used channels.

  In the radio base station AP2 according to the second embodiment, when a signal for disconnecting the connection with the radio base station AP2 is received, the channel number setting unit 45-2 is notified of this, and the channel number setting unit 45-2 is assumed to start processing for setting the number of used channels. The radio base station AP2 according to the second embodiment changes a signal for requesting a new connection to the radio base station AP2 or the number of channels used when performing radio communication with the radio base station AP2. When a signal (trigger signal) is received, an operation similar to that of the radio base station AP1 according to the first embodiment is performed.

  When the radio base station AP2 according to the second embodiment receives a signal (Disassociation signal) for disconnecting from the radio base station AP2 as compared with the radio base station AP1 according to the first embodiment. The operation of the channel number setting unit 45-2 is different. The radio base station AP2 according to the second embodiment and the same part as the radio base station AP1 according to the first embodiment (antenna 10, radio unit 20, modulation / demodulation unit 30, modulation unit 31, demodulation unit 32, carrier About the sense part 33, the transmission part 41-3, the receiving part 42, the MAC control part 43, the memory 44, and the carrier sense control part 46), the same code | symbol is attached | subjected and the description is abbreviate | omitted.

  FIG. 6 is a flowchart showing an operation when the channel number setting unit 45-2 sets the number of used channels when receiving the Dissociation signal. Here, it is assumed that the wireless base station AP2 is connected to y + 1 (y is an integer of 2 or more) wireless terminals and has received a Dissociation signal from one of the wireless terminals. The description of the same operation as that of the channel number setting unit 45 of the first embodiment is omitted.

  First, the radio base station AP2 receives a Dissociation signal (trigger signal) from the connected radio terminal (step S301). In the present embodiment, the trigger signal is a disassociation signal, but it may be a signal for disconnecting the connection with the radio base station AP2.

  Next, the channel number setting unit 45-2 of the radio base station AP2 estimates the distance between each radio terminal other than the transmission source of the dissociation signal and the radio base station AP2 being connected (step S302). . The method by which the channel number setting unit 45-2 estimates the distance between the radio base station AP2 and the radio terminal is as described in the first embodiment.

  Next, the channel number setting unit 45-2 initializes the dummy variable X to 1 (step S303).

  Next, the channel number setting unit 45-2 initializes the dummy variable Y to 1 (step S304).

  Next, the channel number setting unit 45-2 sets the wireless signal reachable distance and the number of used channels to 2 (X = 1) when the number of used channels is 1 (the value of “X” when X = 1). (X + 1 value at the time) and the estimation result of the distance between the radio signal and the distance between the radio base station AP2 and the first radio terminal (the “Y” radio terminal when Y = 1) Are compared (step S305).

  The estimation result of the distance between the radio base station AP and the first radio terminal is larger than the reach of the radio signal when the number of used channels is 2 (value of “X + 1” when X = 1), and the radio When the reach of the radio signal is larger than the estimation result of the distance between the base station AP and the first radio terminal when the number of channels used is 1 (the value of “X” when X = 1) (in step S305) “Yes”), the channel number setting unit 45-2 temporarily sets the current dummy variable value “X” (here, X = 1) as the “temporary setting value” of the number of used channels (step S306).

  On the other hand, when the condition specified in step S305 is not satisfied (“No” in step S305), the channel number setting unit 45-2 determines that the value of the dummy variable Y is the wireless currently connected except for the transmission source of the disassociation signal. It is determined whether or not the number of terminals is equal to “y” (step S307).

  As long as the value of the dummy variable Y does not match “y”, the channel number setting unit 45-2 increases the value of the dummy variable Y by 1 (step S308), and the steps S305 and S306 are performed for the Y-th wireless terminal. Repeat the process.

  On the other hand, if the value of the dummy variable Y matches “y”, the channel number setting unit 45-2 determines whether or not the number of used channels has been provisionally set in step S306 (step S309).

  If provisional setting of the number of used channels has already been performed (“Yes” in step S309), the channel number setting unit 45-2 sets the number of used channels to “temporary setting value” (step S312).

  On the other hand, if the number of used channels has not been provisionally set (“No” in step S309), the channel number setting unit 45-2 increases the value of the dummy variable X by 1 (step S310).

  Next, the channel number setting unit 45-2 determines whether or not the value of the dummy variable X is less than the upper limit value (step S107). The upper limit value is as described in the first embodiment. However, the second value is the minimum value of the number of wireless channels (number of standby channels) that each of the currently connected “y” number of wireless terminals, except for the transmission source of the dissociation signal, is in a standby state. Is used.

  When the value of the dummy variable X is less than the upper limit value (“Yes” in step S311), the channel number setting unit 45-2 performs the processes in steps S305 to S311 again.

  On the other hand, when the value of the dummy variable X is equal to or greater than the upper limit value (“No” in step S311), the channel number setting unit 45-2 sets the number of used channels to “upper limit value” (step S313).

  As described above, according to the wireless base station according to the second embodiment, when a Dissociation signal is received from a connected wireless terminal, the distance between each currently connected wireless terminal other than the transmission source of the Dissociation signal is Since the number of channels used when transmitting a radio signal is set again according to the magnitude relationship between the estimation result and the reach of the radio signal according to the number of channels used, the arrival of radio signals as the number of channels used increases. Realizes high-speed wireless communication with an increased number of channels while suppressing the occurrence of hidden terminal problems and the phenomenon that wireless signals do not reach wireless terminals due to the decrease in distance and wireless communication cannot be continued. can do.

(Third embodiment)
The radio base stations AP1 and AP2 according to the first and second embodiments set the number of channels used when the radio base station AP transmits a radio signal when a trigger signal is received from a connected radio terminal or the like. It was a thing.

  After the radio base station AP3 according to the third embodiment sets the number of channels used when the radio base station AP3 transmits a radio signal, the radio base station AP3 is connecting information indicating the number of channels used. To the wireless terminal. In the radio base station AP3 according to the third embodiment, the process of receiving the trigger signal and setting the number of used channels is the same as that of the radio base stations AP1 and AP2 according to the first and second embodiments.

  Compared with the radio base stations AP1 and AP2 according to the first and second embodiments, the radio base station AP3 according to the third embodiment sets the number of channels used when transmitting radio signals, The difference is that information indicating the number is transmitted to the connected wireless terminal. The radio base station AP3 according to the third embodiment and the same part as the radio base station AP1 according to the first embodiment (antenna 10, radio unit 20, modulation / demodulation unit 30, modulation unit 31, demodulation unit 32, carrier About the sense part 33, the receiving part 42, the MAC control part 43, the memory 44, the channel number setting part 45, and the carrier sense control part 46), the same code | symbol is attached | subjected and the description is abbreviate | omitted.

  Similar to the radio base station AP1 according to the first embodiment, the number of used channels and the used channel number set by the carrier sense control unit 46 are stored in the memory 44 or a memory built in the carrier sense control unit 46. The Rukoto.

  The carrier sense control unit 46 writes the number of used channels and the used channel number in the memory 44, and simultaneously outputs information indicating the number of used channels and the used channel number to the transmitting unit 41-3. The transmission unit 41-3 adds information indicating the number of used channels and the used channel number to the transmission frame and transmits the information to the wireless terminal.

  The frame to which information indicating the number of used channels and the used channel number is added is a Beacon frame that is broadcast to a connected wireless terminal. For example, the transmission unit 41-3 adds information indicating the number of used channels and the used channel number to the Beacon frame body as a Basic Channel Set for a Beacon frame defined by IEEE 802.11.

  In this way, the radio base station AP3 adds information indicating the number of used channels and the used channel number to the Beacon frame and transmits it to the radio terminal connected to the radio base station AP3. The base station AP3 notifies the number of used channels and the used channel number used for wireless communication.

  The radio terminal receives information on the number of used channels and the used channel number from the radio base station AP3, and sets the number of used channels and the used channel number when transmitting a radio signal to the radio base station AP3 according to the received information. To do.

  As described above, according to the radio base station according to the third embodiment, information indicating the number of used channels and the used channel number used by the own radio base station for radio communication is transmitted to the radio terminal currently connected to the own radio base station. By using the same number of used channels and used channel numbers for wireless communication, the number of used channels can be unified between the wireless base station and the wireless terminal, and the wireless signal reaches the wireless terminal. Therefore, it is possible to more reliably suppress the phenomenon that the wireless communication cannot be continued without the occurrence of the hidden terminal problem.

(Fourth embodiment)
In the third embodiment, the wireless base station AP is configured to notify the wireless terminal connected to the wireless base station AP3 of the number of used channels and the used channel number used when the wireless base station AP3 performs wireless communication. The form was described.

  In the fourth embodiment, an embodiment of a radio terminal STA that receives notification of the number of used channels and the used channel number used when the radio base station AP3 performs radio communication will be described.

FIG. 7 is a block diagram showing a configuration of a radio terminal STA according to the fourth embodiment.
The radio terminal STA includes a radio unit 20a, a modem unit 30a, and a MAC processing unit 40a. The modem unit 30a includes a modulation unit 31a, a demodulation unit 32a, and a carrier sense unit 33a. The MAC processing unit 40a includes a transmission unit 41a, a reception unit 42a, a MAC control unit 43a, a memory 44a, and a carrier sense control unit 46a. Note that the wireless terminal STA according to the fourth embodiment does not include the channel number setting unit 45, and the reception unit 42a outputs information indicating the number of used channels and the used channel number to the carrier sense control unit 46a. Is different from the radio base station AP according to the first embodiment. The carrier sense control unit 46a causes the carrier sense unit 33a to perform carrier sense for the radio channel specified by the information indicating the number of used channels and the used channel number output from the receiving unit 42a.

  As described above, according to the wireless terminal according to the fourth embodiment, the wireless base station is notified of the information indicating the number of used channels and the used channel number used for wireless communication, and is used for wireless communication. By making the number of channels and the channel number used the same as those of the radio base station, the number of channels used can be unified between the radio base station and the radio terminal, and the radio signal does not reach the radio terminal and radio communication cannot be continued. The phenomenon that becomes possible and the occurrence of the hidden terminal problem can be more reliably suppressed.

(Fifth embodiment)
In the radio base station AP1 according to the first embodiment, when an association request signal is received from a radio terminal requesting connection, the estimation result of the distance between the radio base station AP1 and the radio terminals A and B, and the channel used The number of channels used when transmitting a radio signal is set according to the size relationship with the reach of the radio signal according to the number.

  The radio base station AP5 according to the fifth embodiment has a larger distance from the radio terminal requesting connection to the radio base station AP5 than the radio terminal that is currently connected, and the radio base station AP5 newly transmits the association request signal. If it is necessary to reset the number of used channels used when performing wireless communication in order to connect to the network, the association request is rejected.

  When the radio base station AP5 according to the fifth embodiment is connected to a plurality of radio terminals, the radio base station AP5 performs dissociation with respect to the radio terminal having the maximum distance from the radio base station AP5 among the plurality of radio terminals. Assumed to be performed.

  The radio base station AP5 notifies the radio terminal that the dissociation is performed when performing the dissociation with respect to the radio terminal having the maximum distance from the radio base station AP5. For example, in the IEEE802.11 standard, “Disassociated associated to inactivity” is described in the reason code of the dissociation frame format.

  Note that in the radio base station AP5 according to the fifth embodiment, the method of performing the dissociation is not limited to the above, and “Disposed channel set issuance is unaccepted due to the“ Disposed frame format reset ”of the IEEE 802.11 standard is reserved. It is also possible to perform dissociation by describing. Further, the present invention is not limited to the above, and other reasons may be described in the Reserved of the IEEE 802.11 standard Dissociation frame format to perform the dissociation.

  In this way, by rejecting an association request of a wireless terminal having a large distance from the own wireless base station and disassociating a wireless terminal that is currently connected and has the largest distance from the own wireless base station, for example, It is possible to prevent high-speed wireless communication by preventing the number of channels used for wireless communication from being set small because the terminal is connected to a wireless terminal having a large distance from its own wireless base station.

  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.

The figure which shows the radio | wireless communications system which concerns on the 1st Embodiment of this invention. The block diagram which shows the structure of the wireless base station which concerns on the 1st Embodiment of this invention. 3 is a flowchart showing an operation of the radio base station according to the first embodiment of the present invention. 3 is a flowchart showing an operation of the radio base station according to the first embodiment of the present invention. The figure which shows the example of the radio channel which a radio base station uses. The flowchart which shows operation | movement of the radio base station which concerns on the 2nd Embodiment of this invention. The block diagram which shows the structure of the radio | wireless terminal which concerns on the 4th Embodiment of this invention.

Explanation of symbols

AP1, AP2, AP3, AP4, AP5 ... wireless base stations A, B, STA ... wireless terminals 10, 10a ... antenna 20, 20a ... wireless unit 30, 30a ... modem unit 31, 31a ... Modulation unit 32, 32a ... Demodulation unit 33, 33a ... Carrier sense unit 40, 40a ... MAC processing unit 41, 41a, 41-3 ... Transmission unit 42, 42a ... Reception unit 43, 43a ... MAC control unit 44, 44a ... Memory 45, 45-2 ... Channel number setting unit 46, 46a ... Carrier sense control unit

Claims (21)

A wireless communication device that performs wireless communication using a plurality of wireless channels,
Receiving means for receiving a first signal from the first wireless communication device;
The reachable distance of the radio signal determined for each number of radio channels used simultaneously when transmitting the radio signal is estimated between the own radio communication device and the first radio communication device according to the first signal. Setting means for setting the number of radio channels used simultaneously when transmitting a radio signal so as to be larger than the estimation result of the distance;
Use radio channels equal to or less than the number of radio channels set by the setting means, and transmit different signals on the respective radio channels, or use more radio channels than the number of radio channels set by the setting means. And a transmission means for transmitting a control signal indicating a period during which the radio channel is exclusively used for each radio channel.   The estimation result is estimated from the number of radio channels used by the first wireless communication apparatus to transmit the first signal and the received signal strength of the first signal received by the receiving means. The wireless communication apparatus according to claim 1. Storage means for storing the number of radio channels used when transmitting the second signal to the first radio communication device;
The first signal describes the received signal strength when the second signal is received by the first wireless communication device,
The radio communication apparatus according to claim 1, wherein the estimation result is estimated from the number of radio channels stored in the storage unit and the received signal strength described in the first signal. Carrier sense control means for determining a radio channel for performing carrier sense according to the number of radio channels set by the setting unit;
The radio communication apparatus according to claim 1, further comprising carrier sense means for starting carrier sense from a radio channel determined by the carrier sense control means. A second storage means for storing a wireless channel used by another wireless communication device or another wireless communication device;
The carrier sense control means is a wireless channel that is not stored in the second storage means among a plurality of wireless channels used for wireless communication, and is continuously greater than or equal to the number of wireless channels set by the setting means. Is defined as the radio channel for carrier sense,
The radio communication apparatus according to claim 4, wherein the carrier sense unit starts carrier sense from a radio channel defined as a radio channel for performing carrier sense by the carrier sense control means.   When the number of radio channels simultaneously used when transmitting a radio signal is x (x is an integer of 1 or more), the reachable distance becomes larger than the estimation result, and the radio channel is used simultaneously when transmitting a radio signal. When the reachable distance becomes smaller than the estimation result when the number of radio channels is x + 1, the setting unit sets the number of radio channels used simultaneously when transmitting a radio signal to x or less. The wireless communication device according to claim 1, wherein the wireless communication device is a wireless communication device.   Even if the number of radio channels simultaneously used when transmitting a radio signal is x (x is an integer equal to or greater than 1), the reachable distance is larger than the estimation result. When the number of radio channels being used is y (y is an integer greater than or equal to 1 and less than x), the setting means sets the number of radio channels simultaneously used when transmitting a radio signal as y. The wireless communication device according to claim 1, wherein the wireless communication device is a wireless communication device.   When the number of radio channels simultaneously used when transmitting a radio signal is x (x is an integer of 1 or more), the reachable distance becomes larger than the estimation result, and the radio channel is used simultaneously when transmitting a radio signal. When the reachable distance becomes smaller than the estimation result when the number of radio channels is x + 1, the transmission means transmits the same signal to each radio channel using x + 1 radio channels simultaneously. The wireless communication apparatus according to any one of claims 1 to 5, wherein: Already connected to the first wireless communication device;
When the number of radio channels simultaneously used when transmitting a radio signal is x + 1 (x is an integer of 1 or more), the reachable distance is the distance between the own radio communication device and the first radio communication device. The setting means sets the number of radio channels simultaneously used when transmitting a radio signal to the second radio communication device to be x or less when the estimation result is smaller than the estimation result. Item 6. The wireless communication device according to any one of Item 5. Third storage means for storing an upper limit value of the number of radio channels used simultaneously when transmitting radio signals,
The said setting means sets the number of radio channels simultaneously used when transmitting a radio signal to the number below the upper limit value memorize | stored in the said 3rd memory | storage means. The wireless communication apparatus according to any one of 5.   When the receiving unit receives a connection request from another wireless communication device, the setting unit sets the number of wireless channels used simultaneously when transmitting a wireless signal to the other wireless communication device. The wireless communication device according to claim 1, wherein the wireless communication device is a wireless communication device.   When the reception unit receives a notification from the other wireless communication device that the number of wireless channels to be set in the standby state has been changed, the setting unit transmits a wireless signal to the other wireless communication device. The radio communication apparatus according to claim 1, wherein the number of radio channels to be used simultaneously is set.   When the receiving unit receives a request for disconnecting the connection to the own wireless communication device from another wireless communication device, the setting unit is a wireless communication device other than the other wireless communication device and is currently connected. The wireless communication according to any one of claims 1 to 10, wherein the number of wireless channels used simultaneously when transmitting a wireless signal is set for each of the wireless communication devices that are connected to each other. apparatus.   The setting unit is a wireless communication device other than the other wireless communication device, and a wireless communication device that simultaneously uses a minimum value of setting results for each of the currently connected wireless communication devices when transmitting a wireless signal. The wireless communication apparatus according to claim 13, wherein the wireless communication apparatus is set with the number of channels.   The transmission means includes the necessity of transmitting a control signal in which a radio channel number used simultaneously when transmitting a radio signal, the number of the radio channels, and a period during which the radio channel is used exclusively. The wireless communication device according to claim 1, wherein the wireless communication device transmits the wireless communication device. Connected to multiple wireless communication devices,
When transmitting radio signals to the plurality of radio communication devices, the transmission means exclusively uses radio channel numbers and the number of radio channels used simultaneously when transmitting the radio signals. The wireless communication apparatus according to claim 1, further comprising: a control signal in which a period for using the wireless communication device is described. A wireless communication device that performs wireless communication using a plurality of wireless channels,
Receiving means for receiving a wireless signal from the first wireless communication device;
A radio signal is transmitted according to a received signal strength of a radio signal received by the own radio communication device from the first radio communication device or a received signal strength of a radio signal received by the first radio communication device from the own radio communication device. Setting means for setting the number of radio channels to be used at the same time,
Use radio channels equal to or less than the number of radio channels set by the setting means, and transmit different signals on the respective radio channels, or use more radio channels than the number of radio channels set by the setting means. And a transmission means for transmitting a control signal indicating a period during which the radio channel is exclusively used for each radio channel. A method of controlling a wireless communication device that performs wireless communication using a plurality of wireless channels,
Receiving a first signal from a first wireless communication device;
The reachable distance of the radio signal determined for each number of radio channels used simultaneously when transmitting the radio signal is estimated between the own radio communication device and the first radio communication device according to the first signal. Set the number of radio channels to be used simultaneously when transmitting radio signals so that it is larger than the distance estimation result,
Use a radio channel equal to or less than the set number of radio channels to transmit a different signal in each radio channel, or use more radio channels than the number of radio channels set by the setting unit, and A control method for a radio communication apparatus, wherein a control signal indicating a period during which the radio channel is used exclusively is transmitted in each radio channel. A method of controlling a wireless communication device that performs wireless communication using a plurality of wireless channels,
Receiving a wireless signal from the first wireless communication device;
A radio signal is transmitted according to a received signal strength of a radio signal received by the own radio communication device from the first radio communication device or a received signal strength of a radio signal received by the first radio communication device from the own radio communication device. Set the number of radio channels to be used at the same time,
Use a radio channel equal to or less than the set number of radio channels to transmit a different signal in each radio channel, or use more radio channels than the number of radio channels set by the setting unit, and A control method for a radio communication apparatus, wherein a control signal indicating a period during which the radio channel is used exclusively is transmitted in each radio channel. A control program for a wireless communication device that performs wireless communication using a plurality of wireless channels,
On the computer,
A function of receiving a first signal from a first wireless communication device;
The reachable distance of the radio signal determined for each number of radio channels used simultaneously when transmitting the radio signal is estimated between the own radio communication device and the first radio communication device according to the first signal. A function for setting the number of radio channels used simultaneously when transmitting a radio signal so as to be larger than the estimation result of the distance;
Use a radio channel equal to or less than the set number of radio channels to transmit a different signal in each radio channel, or use more radio channels than the number of radio channels set by the setting unit, and A control program for a wireless communication apparatus, which realizes a function of transmitting a control signal indicating a period during which the wireless channel is exclusively used in each wireless channel. A control program for a wireless communication device that performs wireless communication using a plurality of wireless channels,
On the computer,
A function of receiving a radio signal from the first radio communication device;
A radio signal is transmitted according to a received signal strength of a radio signal received by the own radio communication device from the first radio communication device or a received signal strength of a radio signal received by the first radio communication device from the own radio communication device. A function to set the number of radio channels to be used at the same time,
Use a radio channel equal to or less than the set number of radio channels to transmit a different signal in each radio channel, or use more radio channels than the number of radio channels set by the setting unit, and A control program for a wireless communication apparatus, which realizes a function of transmitting a control signal indicating a period during which the wireless channel is exclusively used in each wireless channel.

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