JP5169284B2 - Wireless communication apparatus, communication collision avoidance method, program, and recording medium therefor - Google Patents

Description

  The present invention relates to a wireless communication device having two or more antennas and a corresponding wireless transceiver, and a communication collision avoidance method, a program, and a recording medium thereof in such a device.

  In recent years, in wireless communication systems, the problem of packet loss has become serious due to communication using a finite frequency band.

  As a packet collision avoidance technique, an IEEE 802.11 standard for wireless LAN uses an access control method called CSMA / CA (Carrier Sense Multiple Access with Collision Avoidance) method. This method detects whether another access point is communicating, waits if it is communicating, and then transmits after a certain time delay after the other access point communication is not detected. It is a mechanism to start. As a result, the transmission start timing of each access point varies, and the probability of packet collision is low.

  However, when another access point uses a communication channel different from that of the local station, the CSMA / CA method is not useful. For example, in a wireless local area network (LAN), when there are many access points used, the interval between channels is narrowed, and as a result, the frequency of collision between communication packets in other communication channels and communication packets in the own channel increases.

  FIG. 10 shows a state of collision of OFDM (Orthogonal Frequency Division Multiplexing) signals generated between the communication channel (6ch) and the adjacent channel (5ch). Each channel is defined at 5 MHz intervals in the 2.4 GHz band used in the wireless LAN. In communication by wireless LAN, a band of about 20 MHz is required for data transmission / reception, and as shown in FIG. 10, radio wave interference occurs between the communication channel and the adjacent channel, resulting in packet collision. Arise.

  Therefore, in order to avoid collision with packets in different communication channels, the following techniques are considered as other packet collision avoidance techniques.

  It is known to allow multiple types of wireless communication schemes to be used simultaneously in the same area. This technique is described in, for example, Japanese Patent No. 3607632 (Patent Document 1), and as an example, in a wireless communication environment using the same wireless frequency band such as Bluetooth (registered trademark) and wireless LAN, the used frequency band. In this control method, the bandwidth used in the wireless LAN is determined by detecting the thresholds of the plurality of channels, and in Bluetooth communication, hopping is performed by excluding the frequency band used in the wireless LAN.

  It is also known to control the directivity of an adaptive antenna. This technique is described in, for example, Japanese Patent Application Laid-Open No. 2007-13811 (Patent Document 2), and by controlling the directivity of the antenna, the radio signal is controlled in a direction that reduces the influence of interference waves from others. Since transmission and reception are possible, it is possible to increase signal power and reduce signal errors.

  It is also known to use a narrow band filter (SAW filter or the like) with high frequency selectivity. Note that “selectivity” indicates how much a radio wave to be received can be separated from a large number of radio waves and received without interference. Here, “high selectivity” means strong against interference. This technique is described in, for example, Japanese Patent No. 3465707 (Patent Document 3). Narrowband channel filtering is performed for an RSSI (Received Signal Strength Indicator) system, and wideband channel filtering is performed for a reception demodulation system. In a broadband packet radio communication system characterized by a carrier sense multiple access system operated on a harsh frequency arrangement where the occupied bandwidth and modulation side lobes of modulated transmission / reception waves are wide, while the frequency channel spacing is narrow, It is possible to improve the mutual reception adjacent channel interference characteristics between base stations and terminals.

On the other hand, MIMO (Multiple Input Multiple Output) has been attracting attention as a wireless communication technique for expanding the data transmission / reception band by combining a plurality of antennas for the purpose of speeding up the wireless LAN. In theory, simultaneous communication of different data becomes possible, and an effect equivalent to that when the number of antennas is two is increased twice, and when the number of antennas is three, the same effect is obtained. MIMO is introduced in IEEE802.11n, which is a high-speed wireless LAN standard with an effective over 100 Mbps.
Japanese Patent No. 3607632 JP 2007-13811 A Japanese Patent No. 3465707

  However, since the new standard IEEE802.11n is shared with the existing standard IEEE802.11b / g / a in a finite frequency band, the problem of packet loss becomes more serious, and as a result, the speed cannot be increased. There is a problem that there is. Therefore, a packet collision avoidance technique is important even in a wireless communication system employing MIMO. However, the conventional packet collision avoidance technique described above is intended to avoid collision between packets transmitted from different terminals, and has a plurality of antennas as in MIMO and transmits packets from each antenna. There is a problem that a terminal cannot avoid collision between packets transmitted by the terminal itself.

  In view of the above problems, the present invention is a wireless communication apparatus having two or more antennas and corresponding wireless transceivers, and is capable of avoiding a communication collision caused by radio waves transmitted from itself and other terminals. An object is to provide a communication device. Further, the present invention provides a communication collision avoidance method capable of avoiding a communication collision caused by radio waves transmitted from itself and other terminals in a wireless communication apparatus having two or more antennas and a corresponding wireless transceiver, An object of the present invention is to provide a communication collision avoidance program for causing a computer to execute such a procedure for communication collision avoidance, and a recording medium thereof.

  In order to achieve the above object, a wireless communication apparatus of the present invention is a wireless communication apparatus having two or more antennas and a corresponding wireless transceiver, wherein at least one of the wireless transceivers is a predetermined one. The communication frequency channel and the detection frequency channel are set such that at least one other radio transmitter / receiver is set to a detection frequency channel different from the communication frequency channel. Two or more frequency channel determination means for determining a frequency channel, radio wave detection means for detecting radio waves in the communication frequency channel and the detection frequency channel, and a state of the radio wave detected by the radio wave detection means A radio wave condition determining unit; and a notifying unit for notifying the communication collision avoidance unit of a determination result by the radio wave condition determining unit. The communication collision avoidance means, based on the notification from the notification unit, and performs signal transmission timing control operation for the communication collision avoidance.

  This makes it possible to check radio wave conditions not only for communication frequency channels but also for other frequency channels where communication collisions can occur, and for communication collisions with other terminals that use a frequency channel different from itself. Can be avoided.

  In the wireless communication apparatus, the notification means notifies the communication collision avoidance means of the determination result by the radio wave state determination means when all the wireless transceivers are not transmitting data.

  As a result, it is possible to avoid the occurrence of a communication collision caused by a plurality of radio waves transmitted by itself.

  In the wireless communication apparatus, the radio wave state determination unit considers that the radio wave is detected when the strength of the radio wave detected by the radio wave detection unit is higher than a predetermined threshold, and the strength of the radio wave is When it is considered that at least one of the radio waves detected by the radio wave detection means by the comparison means and the comparison means that the radio waves are not detected when the threshold is lower than a predetermined threshold, the communication Logic communication means for determining that the radio wave condition in the frequency channel and the detection frequency channel is busy, the communication collision avoidance means is configured to transmit the communication frequency channel and the communication from the radio wave condition determination means via the notification means. Signal transmission timing for avoiding communication collision when receiving notification that the radio wave condition in the detection frequency channel is not busy Perform a grayed control operation.

  As a result, it is possible to determine whether or not a radio wave having such a strength that a communication collision actually occurs is transmitted by another terminal.

  The wireless communication apparatus further includes a frequency channel selection unit that selects the communication frequency channel, and the frequency channel determination unit includes at least one side or both sides of the communication frequency channel selected by the frequency channel selection unit. The adjacent frequency is set as the detection frequency channel. In this wireless communication apparatus, the frequency selection means selects the communication frequency channel by user input or frequency scan.

  Accordingly, it is possible to easily set the adjacent frequency channel in the RF transceiver and receive the radio wave without obtaining the information regarding the adjacent frequency channel in which a communication collision may occur.

  In the wireless communication apparatus, when it is recognized in advance that there is no other frequency channel other than the communication frequency channel, the communication frequency channel determination means uses the same communication channel via each of the wireless transceivers. All the wireless transceivers are set to the same communication frequency channel so that the data divided and multiplexed in the frequency channel are transmitted simultaneously.

  For example, in a situation where it is known in advance that there is no frequency channel where communication collision can occur, such as a finite space where there is no other terminal, it is not necessary to perform radio wave detection on frequency channels other than the communication frequency channel. Unnecessary radio wave detection steps can be omitted.

  In the wireless communication apparatus, the predetermined threshold has different values for each of the communication frequency channel and the detection frequency channel.

  As a result, the reception S / N characteristic of the device is good, and even if radio waves in other frequency channels cannot be detected at all with the thresholds matched to the communication frequency channel, other values can be set by setting different values as threshold values. Radio waves in the frequency channel can be detected.

  In the wireless communication apparatus, the signal transmission timing control operation for avoiding a communication collision by the communication collision avoiding means is back-off control.

  In order to achieve the above object, a communication collision avoidance method according to the present invention is a communication collision avoidance method in a wireless communication apparatus having two or more antennas and a corresponding wireless transceiver, wherein at least one of the wireless transceivers The radio transceiver is set to a predetermined communication frequency channel, and at least one other radio transceiver of the radio transceiver is set to a detection frequency channel different from the communication frequency channel. A frequency channel determination step for determining a frequency channel and the detection frequency channel, a radio wave detection step for detecting a radio wave in the communication frequency channel and the detection frequency channel, and a state of the radio wave detected in the radio wave detection step. Radio wave condition determination step for determination, and determination result obtained in the radio wave condition determination step A notification step of notifying that, based on the notification by the notification step, and a transmission timing control step of performing signal transmission timing control for communication collision avoidance.

  According to the communication collision avoidance method, the determination result obtained in the radio wave state determination step is notified in the notification step when all the wireless transceivers are not transmitting data.

  According to the communication collision avoidance method, the radio wave state determination step includes a comparison step for comparing the strength of the radio wave detected in the radio wave detection step with a predetermined threshold value, and the strength of the radio wave is higher than the predetermined threshold value. The radio wave is considered to be detected, and when the strength of the radio wave is lower than the predetermined threshold, the radio wave detection judgment step that the radio wave is considered not to be detected, and the radio wave detection judgment step A radio wave state determining step for determining that the radio wave state in the communication frequency channel and the detection frequency channel is busy if at least one of them is detected, and in the transmission timing control step, In the signal transmission timing control, the determination result notified in the notification step is Radio wave condition at wave numbers of channels and the detection frequency channel is performed to indicate that it is not busy.

  The communication collision avoidance method further includes a frequency channel selection step of selecting the communication frequency channel, and in the frequency channel determination step, the detection frequency channel is the communication channel selected in the frequency channel selection step. It is set to an adjacent frequency on at least one side or both sides of the frequency channel.

  According to the communication collision avoidance method, in the frequency selection step, the communication frequency channel is selected by user input or frequency scan.

  In the communication collision avoidance method, when it is recognized in advance that there is no other frequency channel other than the communication frequency channel, the communication frequency channel determination step includes the same communication via each of the radio transceivers. All the radio transceivers are set to the same communication frequency channel so that the data divided and multiplexed in the frequency channel for transmission is transmitted simultaneously.

  In order to achieve the above object, the present invention may be applied to a communication collision avoidance program that causes a computer to execute a procedure for avoiding communication collision as described above, and a recording medium thereof.

  According to the present invention, there is provided a wireless communication apparatus having two or more antennas and a corresponding wireless transmitter / receiver, and capable of avoiding a communication collision caused by radio waves transmitted from itself and other terminals. Is possible. Further, according to the present invention, in a wireless communication device having two or more antennas and a corresponding wireless transceiver, a communication collision avoidance method capable of avoiding a communication collision caused by radio waves transmitted from itself and other terminals, It is possible to provide a communication collision avoidance program for causing a computer to execute such a procedure for avoiding communication collision and a recording medium thereof.

  The best mode for carrying out the present invention will be described below with reference to the accompanying drawings.

[Constitution]
FIG. 1 shows a configuration of a MIMO wireless communication apparatus according to an embodiment of the present invention.

  1 has a plurality of RF (Radio Frequency) systems, modulation / demodulation for detecting a received signal and modulating a transmission signal, as in a configuration generally found in a conventional MIMO wireless communication device. A protocol unit 119 that defines a communication protocol (for example, information format and communication procedure) between the unit 118 and the transmission / reception side terminal, a control unit 120 that controls the operation of each unit of the wireless communication device 1, and a user that receives user input And an input interface 123. Each RF system includes antennas 100 to 102, switches 103 to 105 for switching transmission and reception, RF transceivers 106 to 108 as radio signal transceivers, an analog-digital converter (ADC) that converts received signals into digital signals, and Digital-analog converters (DACs) 109 to 111 that convert transmission signals into analog signals, and oscillators 112 to 114 as frequency channel determination means that determine the frequency channels of the RF transceivers 106 to 108 are included. In the wireless communication device 1 shown in FIG. 1, three RF systems are provided as an example.

  In the wireless communication device 1 in the normal communication operation mode, all the RF transceivers 106 to 108 are set to the same communication frequency channel. The wireless communication device 1 can multiplex transmission data and transmit the multiplexed data simultaneously through the RF transceivers 106 to 108.

  Further, in contrast to the conventional wireless communication device, the wireless communication device 1 can set a different frequency channel for each RF transceiver. As a result, the wireless communication device 1 can detect whether or not there is a radio wave in a different frequency channel, so that a packet in a different frequency channel collides with a packet in a communication frequency channel set for itself. It can be avoided.

  For example, when the communication frequency channel is 6ch, at least one RF transceiver 106 is set to 6ch as the frequency channel. At this time, if there is a possibility that another frequency channel 5ch or 7ch adjacent to the communication frequency channel is used by another terminal, this adjacent frequency channel 5ch or 7ch is used for communication by the other terminal. In order to detect whether or not the other RF transceiver 107 is set, 5ch or 7ch is set as the frequency channel. This is realized by changing the oscillation frequency of the oscillators 112 to 114. The wireless communication device 1 further includes a frequency channel selection unit 122 that selects a communication frequency channel in the protocol processing unit 119. The protocol processing unit 119 sets at least one of the oscillators 112 to 114 to have an oscillation frequency corresponding to the communication frequency channel selected by the frequency channel selection unit 122, and other packet collision may occur. At least one other oscillator is set to have an oscillation frequency corresponding to the frequency channel. The frequency channel selection unit 122 can select a communication frequency channel by user input or frequency scan.

  In order to avoid packet collision, the wireless communication apparatus 1 has a communication collision avoidance unit 121 capable of controlling the timing of signal transmission in the protocol processing unit 119, and each of the RF transceivers 106 to 108 set. The radio wave detection unit 115 that detects radio waves in the frequency channel, the radio wave state determination unit 116 that determines the state of the radio wave detected by the radio wave detection unit 115, and the determination result by the radio wave state determination unit 116 are sent to the communication collision avoidance unit 121. A notification unit 117 for notification. Upon receiving the notification from the notification unit 117, the communication collision avoidance unit 121 can perform a signal transmission timing control operation for packet collision avoidance. In the present embodiment, it is assumed that the signal transmission timing control performed by the communication collision avoidance unit 121 is back-off control performed by the conventional CSMA / CA method.

  FIG. 2 shows in detail a part of the wireless communication apparatus 1 including the radio wave detection unit 115, the radio wave state determination unit 116, and the notification unit 117.

  The radio wave detection unit 115 includes analog-digital (A / D) converters 200 to 202. The A / D converters 200 to 202 detect the voltage values of the IQ signals of the RF systems output from the RF transceivers 106 to 108, convert them into digital values, and output the digital values. Such operation of the A / D converter is generally called RSSI (Received Signal Strength Indicator). In operation, the A / D converters 200 to 202 are input with a control signal from the protocol processing unit 119 and input with a clock signal corresponding to the frequency channel set for each RF system from the oscillators 112 to 114. .

  The radio wave state determination unit 116 includes comparison units 203 to 205 and a logic circuit 206. Each of the comparison units 203 to 205 compares whether or not the digital voltage value output from the radio wave detection unit 115 is higher than a predetermined threshold value, and if the voltage value is higher than the predetermined threshold value, the RF system If the voltage value is lower than a predetermined threshold value, it is assumed that no radio wave is detected in the RF system, and no radio wave is detected. A detection signal (eg, “0”) is output. The threshold value is input from the protocol processing unit 119 to each of the comparison units 203 to 205. The threshold value can be set differently for each RF system via the user input interface 123. For example, the threshold value for the communication frequency channel is set higher than the detection frequency channel for packet collision avoidance. Can be done.

  The logic circuit 206 calculates the logical sum of the comparison results output by the comparison units 203 to 205, and determines that the radio wave state is busy if there is at least one RF system that is considered to have detected the radio wave. In this embodiment, in this case, the logic circuit 206 outputs “1”.

  The notification unit 117 notifies the communication collision avoidance unit 121 of the determination result output from the logic circuit 206. The notification unit 117 receives the RxEnable signal from the protocol processing unit 119 and notifies the communication collision avoidance unit 121 of the determination result when this signal is enabled. The RxEnable signal is a signal that is enabled when all the RF systems of the wireless communication device 1 are not transmitting data. The RF system set to the detection frequency channel for packet collision avoidance works exclusively as a receiver, but the RF system set to the communication frequency channel may serve as a transmitter as well as a receiver. With this signal, it is possible to determine a state in which the wireless communication apparatus 1 is not transmitting data completely.

  Hereinafter, the operation of the wireless communication apparatus 1 of the present invention in the embodiment shown in FIGS. 1 and 2 will be described.

[Frequency channel setting]
FIG. 3 is a diagram illustrating an operation flow at the time of initial setting of the wireless communication device 1 according to the present embodiment. By the initial setting, each RF transceiver of the wireless communication device 1 is set to the same or different frequency channel.

  First, in step S <b> 101, the control unit 120 issues a scan command to the protocol processing unit 119 so as to scan all channels defined in the protocol processing unit 119. In response to this, the protocol processing unit 119 causes each RF system to execute a frequency scan. This frequency scan operation is executed until the control unit 120 confirms the acquisition of the scan result in step S102. Although the frequency scan operation is not described in detail here, generally, there are known methods such as an active method using a NULL frame and a passive method using a beacon.

  When the acquisition of the scan result is confirmed in the control unit 120, in step S103, the control unit 120 sets a communication frequency channel in a specific RF transceiver (for example, the RF transceiver 106 in FIG. 1) in the protocol processing unit 119. Issue a frequency setting command. In response to this, in step S104, the protocol processing unit 119 sets the oscillation frequency of the oscillator 112 connected to the specific RF transceiver 106 to a frequency corresponding to the communication frequency channel via the frequency channel selection unit 122. . Thus, the communication frequency channel is set in the RF transceiver 106.

  Next, in step S105, the control unit 120 determines whether it is necessary to set the same communication frequency channel for other RF transceivers based on the user setting. If necessary, the process returns to step S104, and the control unit 120 issues a frequency setting command to the protocol processing unit 119 so as to set the communication frequency channel for the other RF transceivers. The unit 119 sets the oscillation frequency of the oscillator 113 or 114 connected to the other RF transceiver 107 or 108 to a frequency corresponding to the communication frequency channel via the frequency channel selection unit 122.

  When the communication frequency channel is not set in the other RF transceiver, in step S106, the control unit 120 needs to set the frequency channel adjacent to the communication frequency channel in the other RF transceiver based on the user setting. Determine whether or not. If necessary, in step S107, the control unit 120 issues a frequency setting command to the protocol processing unit 119 so as to set an adjacent frequency channel for another RF transceiver, and the protocol processing unit 119 responds accordingly. The oscillation frequency of the oscillator 113 or 114 connected to the other RF transceiver 107 or 108 is set to a frequency corresponding to the adjacent frequency channel via the frequency channel selection unit 122.

  When the adjacent frequency channel is not set in the other RF transceiver, in step S108, based on the user setting, the control unit 120 sets the other RF transceiver to other RF transceiver other than the neighbor that avoids the packet collision acquired by the previous frequency scan. Determine whether it is necessary to set the frequency channel. If necessary, in step S109, the control unit 120 issues a frequency setting command to the protocol processing unit 119 to set another frequency channel for avoiding packet collision with respect to another RF transceiver, and in response to this, Then, the protocol processing unit 119 sets the oscillation frequency of the oscillator 113 or 114 connected to the other RF transceiver 107 or 108 to a frequency corresponding to the other frequency channel via the frequency channel selection unit 122.

  After setting frequency channels for avoiding packet collision in other RF transceivers, in step S110, the control unit 120 sets frequency channels for avoiding packet collision for the remaining RF transceivers based on user settings. Determine if you need to. If necessary, the wireless communication device 1 repeats the operations in steps S106 to S110.

  When the frequency channel for avoiding packet collision is not set in the other RF transceiver, the wireless communication device 1 ends the initial setting. After completion of the initial setting, the wireless communication device 1 starts a data transmission / reception operation.

  In the present embodiment, the frequency scan is performed to determine the communication frequency channel. However, as a modification, the communication frequency channel may be set by the user via the user input interface 123.

  Further, the control unit 120 follows the user setting in each determination step. For example, the user can set the frequency channel for communication to be set, the frequency channel adjacent to the frequency channel for avoiding packet collision, or the like. If it is possible to set in advance via the user input interface 123 the number of RF transceivers to be set and the number of RF transceivers to set adjacent frequency channels or other frequency channels, The determination step is performed automatically. Alternatively, the user may input user settings for each determination step.

[Signal transmission timing control for packet collision avoidance]
FIG. 4 is a diagram illustrating an operation flow for avoiding packet collision in the wireless communication device 1 according to the present embodiment.

  First, in step S201, each of the RF transceivers 106 to 108 receives a signal transmitted from another terminal on the frequency channel set for itself. Each RF transceiver 106-108 generates an IQ signal from the received signal.

  In step S202, the radio wave detection unit 115 detects the voltage value of the IQ signal output from each of the RF transceivers 106 to 108 by the A / D converters 200 to 202, converts the voltage value into a digital value, and outputs the digital value.

  In step S203, the radio wave state determination unit 116 compares the digital voltage value output from the radio wave detection unit 115 with the comparison units 203 to 205 to determine whether the voltage value is higher than the predetermined threshold value. Is higher, the radio wave detection signal (for example, “1”) is output assuming that the radio wave is detected in the RF system. Is detected as a radio wave non-detection signal (eg, “0”). Then, the radio wave state determination unit 116 calculates the logical sum of the output radio wave detection signal and the radio wave non-detection signal by the logic circuit 206, and if there is at least one RF system in which the radio wave is detected, the radio wave state Is determined to be busy. When the radio wave state is busy, the wireless communication device 1 repeats the operations in steps S201 to S203.

  On the other hand, if the radio wave state is not busy, in step S204, the notification unit 117 refers to the RxEnable signal to determine whether all the RF transceivers 106 to 108 of the wireless communication device 1 are not transmitting data. Check. If none of the RF transceivers 106 to 108 transmit data, the communication unit 117 notifies the communication collision avoidance unit 121 that the radio wave state is not busy in step S205. If any one of the RF transceivers is transmitting data, the notification unit 117 waits for a certain time until the transmission is completed. If the transmission is not completed even after waiting for a certain time, the wireless communication device 1 may repeat the operations of steps S201 to S205 again.

  In response to the notification from the communication unit 117, the communication collision avoidance unit 121 executes back-off control in step S206. That is, the communication collision avoidance unit 121 waits for a fixed time called IFS (Interframe Space) determined by the standard, then generates a random number, and multiplies the random number value by a fixed time called “slot time”. Wait until the time obtained (generally called “backoff time”) elapses.

  After the elapse of the back-off time, in step S207, the communication collision avoidance unit 121 starts data transmission by the RF transceiver set to the communication frequency channel.

  In this way, the communication collision avoidance unit 121 can receive the notification from the notification unit 117 and perform a signal transmission timing control operation for packet collision avoidance. In other words, not only the frequency channel for communication, but also the frequency channel adjacent to it and / or other frequency channels are not used for communication by other terminals, and the wireless communication device 1 itself does not transmit any data. If it is in the state, data transmission is started. Therefore, the wireless communication device 1 according to the present embodiment is suitable for a MIMO wireless communication device having a plurality of RF systems while eliminating the disadvantage of the CSMA / CA method that does not function effectively when the channel is different from the set channel. Packet collision avoidance operation can be provided.

  FIG. 5 is a diagram illustrating signal transmission timing of the wireless communication device 1 according to the present embodiment.

  For example, when the communication frequency channel is set to 6ch, consider a case where at least one of the RF transceivers not used for data transmission / reception is set to 5ch, which is an adjacent frequency channel.

  When no signal is received on channel 6 as shown in (a) at time t1, radio wave state determination unit 116 assumes that no radio wave is detected on channel 6 and corresponds to that channel as shown in (b). '0' is output as a radio wave non-detection signal from the comparison unit. In a conventional CSMA / CA wireless communication apparatus that only confirms the radio wave condition in the communication frequency channel, as indicated by the broken line in (e), a fixed time (IFS + backoff time) after no radio wave is detected in 6ch After that, at time t2, data transmission is started. At this time, as shown in (c), if another terminal is communicating using 5ch of the adjacent frequency channel, the data packet transmitted from the wireless communication device in 6ch is communicated in 5ch. There is a high possibility of colliding with packets from other terminals.

  However, since the radio communication apparatus 1 according to the present embodiment can detect the radio wave state of the adjacent frequency channel in addition to the communication frequency channel, such a situation is avoided. When no signal is received on channel 5 as shown in (c) at time t3, radio wave state determination unit 116 assumes that no radio wave is detected on channel 5 and corresponds to that channel as shown in channel (d). '0' is output as a radio wave non-detection signal from the comparison unit. At this time, since the radio wave is not detected even in the communication frequency channel 6ch, the radio wave state determination unit 116 takes the logical sum of the 6ch and 5ch radio wave undetected signals, and as shown in (f), A notification signal '0' indicating that is not busy is output. Upon receiving this notification signal, the communication collision avoidance unit 121 starts data transmission at time t4 after a certain time (IFS + backoff time), as indicated by a solid line in (e).

[Automatic setting of frequency channel for detection]
In the initial setting operation described with reference to FIG. 3, after a communication frequency channel is set by user input or frequency scan, a detection frequency channel adjacent to or other packet collision avoidance is set by user setting and Assigned to the RF transceiver based on the results of the frequency scan. However, if the number of RF systems is known in advance, the adjacent frequency channel can be automatically set as the detection frequency channel in the RF transceiver without using the user setting and / or the frequency scan result.

  FIG. 6 is a diagram illustrating a flow of the automatic setting operation of the detection frequency channel of the wireless communication device 1 according to the present embodiment.

  After the communication frequency channel is set in at least one RF transceiver in steps S101 to S105 shown in FIG. 3, the protocol processing unit 119 sets the specific RF transceiver in the frequency channel selection unit 122 in step S301. It is determined what the frequency channel for communication is and returns to the control unit 120. Here, it is assumed that the determined communication frequency channel is Nch (N is a positive integer). In step S302, the control unit 120 checks whether there are two or more RF transceivers for which no communication frequency channel is set. If there are two or more unconfigured RF transceivers, in step S303, the control unit 120 causes the protocol processing unit 119 to set the adjacent frequency channels (N + 1) ch and (N-1) ch above and below the communication frequency channel to the protocol processing unit 119. Each of the two RF transceivers to be set is set.

  On the other hand, if there is only one unconfigured RF transceiver, in step S304, the control unit 120 instructs the protocol processing unit 119 to select either the upper or lower adjacent frequency channel (N + 1) according to the user setting or randomly. ) Ch or (N-1) ch is set in the RF transceiver, and then the automatic setting operation is terminated.

  After step S303, in step S305, the control unit 120 checks whether there is still an unconfigured RF transceiver. If there are still unconfigured RF transceivers, in step S306, the control unit 120 causes the protocol processing unit 119 to set the remaining unconfigured RF transceivers to “unused”, and then ends the automatic setting operation. To do.

  As a modification, as long as there are unconfigured RF transceivers, it is possible to continue to set the RF transceivers as detection transceivers for avoiding packet collision. Thus, for example, the frequency channels (N + 2) ch and (N-2) ch adjacent to the upper and lower adjacent frequency channels (N + 1) ch and (N-1) ch above and below the communication frequency channel are left as remaining. Can be set to an unconfigured RF transceiver.

[Select operation mode]
In a situation where it is known in advance that other terminals are not communicating using a frequency channel in which packet collision may occur, the above-described operation for avoiding packet collision need not be performed. The user can select whether or not to perform a packet collision avoidance operation via the user input interface 123 provided in the wireless communication device 1.

  FIG. 7 is a diagram illustrating an operation flow of operation mode selection of the wireless communication device 1 according to the present embodiment.

  Before performing communication, in step S401, the control unit 120 confirms whether or not execution of a packet collision avoidance operation is selected. If execution of the packet collision avoidance operation is selected by the user input interface 123, the process proceeds to step S402, and the wireless communication device 1 performs the packet collision avoidance operation described with reference to FIGS. Thereafter, when there is no possibility of packet collision, the wireless communication device 1 starts data transmission in step S403.

  On the other hand, if execution of the packet collision avoidance operation is not selected, the wireless communication apparatus 1 starts data transmission in the normal communication operation mode without performing the packet collision avoidance operation. At this time, the wireless communication apparatus 1 multiplexes transmission data and transmits the multiplexed data simultaneously through the RF transceivers 106 to 108 in a state where all the RF transceivers 106 to 108 are set to the same communication frequency channel. Can do.

[Radio wave detection judgment threshold setting]
As described above, the radio wave state determination unit 116 includes the comparison units 203 to 205 that compare the digital voltage value indicating the strength of the radio wave detected by the radio wave detection unit 115 with a predetermined threshold value. If the voltage value is higher than the threshold value, the radio wave state determination unit 116 considers that the radio wave is detected in the RF system, and if the voltage value is lower than the threshold value, the radio wave state determination unit 116 regards that the radio wave is not detected in the RF system. This threshold value may have the same value for all the RF systems, but a different value can be set for each RF system via the user input interface 123. This is effective when the reception S / N characteristic of the apparatus is good and radio waves in other frequency channels cannot be detected at all with a threshold value matched to the communication frequency channel.

  FIG. 8 is a diagram showing an operation flow for setting a threshold for radio wave detection determination in the wireless communication device 1 according to the present embodiment.

  First, in step S501, the power of the wireless communication apparatus 1 is turned on. When the power is turned on, in step S <b> 502, the control unit 120 sets a common threshold value set in advance by user setting or default setting at the time of manufacture in the comparison units 203 to 205 of the radio wave state determination unit 116. .

  Thereafter, if necessary, in step S503, the user instructs the change of the threshold value via the user input interface 123. If there is an instruction to change the threshold value by the user, in step S504, the user selects an RF system whose threshold value for radio wave detection is changed via the user input interface 123, and the selected RF system is selected. On the other hand, a new threshold value after the change is set. In accordance with the user input, in step S505, the control unit 120 changes the threshold value of the comparison units 203 to 205 corresponding to the selected RF system.

[Modification]
As described above, in the embodiment of the present invention, the wireless LAN is described in particular. However, the present invention can be applied to other systems in which communication collision is a problem.

  The functions of the present invention are performed by a program stored in a memory such as a hard disk (HDD), a read-only memory (ROM) of an information processing apparatus, or a computer-readable recording medium such as a compact disk (CD). Alternatively, it may be realized as hardware in the information processing apparatus. FIG. 9 shows an example of a computer that executes a communication collision avoidance program according to the present invention.

  As shown in FIG. 9, the computer 10 includes a drive device 11, an auxiliary storage device 12, a memory device 13, an arithmetic processing device 14, and an interface device 15 that are connected to each other via a bus 16.

  The drive device 11 is a device for reading the recording medium 17. When the recording medium 17 in which a program for realizing processing in the computer 10 (that is, a communication collision avoidance program) is recorded is set in the drive device 11, the program is transferred from the recording medium 17 through the drive device 11 to the auxiliary storage device 12. To be installed.

  The interface device 15 is a device for connecting the computer 10 to an external network. The computer 10 can also obtain a program from a server or the Internet via an external network.

  The auxiliary storage device 12 is a device that stores a program that is installed or acquired via a network, and stores necessary files, data, and the like. The memory device 23 is a device that reads a program from the auxiliary storage device 22 and stores it when there is an instruction to start the program. The arithmetic processing device 24 is a device that executes functions related to the computer 10 in accordance with a program stored in the memory device 23.

  Thus, the computer can execute the communication collision avoidance program of the present invention.

  Although the best mode for carrying out the invention has been described above, the present invention is not limited to the embodiment described in the best mode. Modifications can be made without departing from the spirit of the present invention.

1 illustrates a configuration of a MIMO wireless communication apparatus according to an embodiment of the present invention. Part of the wireless communication device 1 shown in FIG. 1 is shown in detail. It is a flowchart of the initial setting operation | movement of the radio | wireless communication apparatus according to embodiment of this invention. It is a flowchart of the packet collision avoidance operation | movement of the radio | wireless communication apparatus according to embodiment of this invention. It is a figure showing the signal transmission timing of the radio | wireless communication apparatus of embodiment of this invention. It is a flowchart of the automatic setting operation | movement of the frequency channel for a detection of the radio | wireless communication apparatus according to embodiment of this invention. It is a flowchart of the operation mode selection operation | movement of the radio | wireless communication apparatus according to embodiment of this invention. It is a flowchart of the threshold value setting operation | movement for the radio wave detection judgment of the radio | wireless communication apparatus according to embodiment of this invention. 1 represents an example of a computer that executes a communication collision avoidance program according to the present invention. This represents a state of collision of OFDM signals occurring between a communication channel and an adjacent channel.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Wireless communication apparatus 10 Computer 17 Recording medium 100-102 Antenna 106-108 RF transceiver 112-114 Oscillator 115 Radio wave detection part 116 Radio wave state judgment part 117 Notification part 120 Control part 121 Packet collision avoidance part 122 Frequency selection part 123 User input interface

Claims (20)

A wireless communication device having two or more antennas and a corresponding wireless transceiver,
At least one of the radio transceivers is set to a predetermined communication frequency channel, and at least one other radio transceiver of the radio transceiver is a detection frequency channel different from the communication frequency channel. Two or more frequency channel determination means for determining the communication frequency channel and the detection frequency channel so as to be set to
Check the number of other wireless transceivers not set with the communication frequency channel, and if the number is 2 or more, the frequency channel determination means, the upper and lower channels of the communication frequency channel to each of the above If at least one other radio transceiver is set as a frequency channel for detection, and the number is 1, the frequency channel determination means causes either one of the upper and lower channels of the communication frequency channel to be Control means for setting other radio transceiver as a detection frequency channel;
Radio wave detection means for detecting radio waves in the communication frequency channel and the detection frequency channel;
Radio wave state determination means for determining the state of the radio wave detected by the radio wave detection means;
Notification means for notifying the communication collision avoidance means of the determination result by the radio wave state determination means,
The communication collision avoidance unit is a wireless communication apparatus that performs a signal transmission timing control operation for communication collision avoidance based on a notification from the notification unit.   The wireless communication apparatus according to claim 1, wherein the notifying unit notifies a determination result by the radio wave state determining unit to a communication collision avoiding unit when all the wireless transceivers are not transmitting data. The radio wave condition judging means is
When the strength of the radio wave detected by the radio wave detection means is higher than a predetermined threshold, the radio wave is considered to be detected, and the radio wave is detected when the strength of the radio wave is lower than the predetermined threshold. A means of comparison deemed to have not been done,
Logic means for determining that the radio frequency state in the communication frequency channel and the detection frequency channel is busy if it is considered that at least one of the radio waves detected by the radio wave detection means is detected by the comparison means. Have
The communication collision avoidance means is for avoiding a communication collision when receiving a notification from the radio wave state determination means via the notification means that the radio wave state in the communication frequency channel and the detection frequency channel is not busy. The wireless communication apparatus according to claim 1, wherein the signal transmission timing control operation is performed. Further have a frequency channel selection means for selecting the communication frequency channels, the wireless communication device as claimed in any one of claims 1 to 3. The radio communication apparatus according to claim 4, wherein the frequency channel selection unit selects the communication frequency channel by user input or frequency scan. When it is recognized in advance that there is no frequency channel other than the communication frequency channel,
Before distichum wavenumber channel decision means, wherein the same said communication frequency channel via a respective radio transceiver as multiplexed divided data is sent simultaneously, all of the wireless transceiver of the same said communication frequency The wireless communication device according to claim 1, wherein the wireless communication device is set to a channel.   The wireless communication apparatus according to claim 3, wherein the predetermined threshold has different values for each of the communication frequency channel and the detection frequency channel.   The radio communication apparatus according to claim 1, wherein a signal transmission timing control operation for avoiding a communication collision by the communication collision avoiding unit is a back-off control. A communication collision avoidance method in a wireless communication apparatus having two or more antennas and a corresponding wireless transceiver,
At least one of the radio transceivers is set to a predetermined communication frequency channel, and at least one other radio transceiver of the radio transceiver is a detection frequency channel different from the communication frequency channel. A frequency channel determining step for determining the communication frequency channel and the detection frequency channel to be set to:
A radio wave detection step of detecting radio waves in the communication frequency channel and the detection frequency channel;
A radio wave state determination step for determining the state of the radio wave detected in the radio wave detection step;
A notification step of notifying the determination result obtained in the radio wave state determination step;
Based on notification by the notification step, possess a transmission timing control step of performing signal transmission timing control for communication collision avoidance,
The communication collision avoidance method further includes a step of confirming the number of other radio transceivers in which the communication frequency channel is not set, and if the number is 2 or more, in the frequency channel determination step, If each of the upper and lower channels of the communication frequency channel is set as at least one other radio transceiver as the detection frequency channel, and the number is 1, then in the frequency channel determination step, the communication A communication collision avoidance method in which one of the upper and lower channels of the frequency channel for use is set in the other radio transceiver as the detection frequency channel .   The communication collision avoidance method according to claim 9, wherein the determination result obtained in the radio wave state determination step is notified when all the wireless transceivers are not transmitting data in the notification step. The radio wave condition determining step includes:
A comparison step of comparing a predetermined threshold value with the strength of the radio wave detected in the radio wave detection step;
Radio wave detection that considers that the radio wave is detected when the strength of the radio wave is higher than the predetermined threshold, and that the radio wave is not detected when the strength of the radio wave is lower than the predetermined threshold A decision step;
A radio wave condition determining step for determining that the radio wave condition in the communication frequency channel and the detection frequency channel is busy if it is considered that at least one of the radio waves is detected in the radio wave detection determining step. ,
In the transmission timing control step, the signal transmission timing control is executed when the determination result notified in the notification step indicates that the radio wave state in the communication frequency channel and the detection frequency channel is not busy. The communication collision avoidance method according to claim 9 or 10. The further have a frequency channel selection step of selecting a frequency channel for communication, a communication collision avoidance method as claimed in any one of claims 9 to 11. The communication collision avoidance method according to claim 12, wherein, in the frequency channel selection step, the communication frequency channel is selected by a user input or a frequency scan. When it is recognized in advance that there is no frequency channel other than the communication frequency channel,
Before distichum wavenumber channel determining step, the so-multiplexed divided data is sent simultaneously in the same said communication frequency channel via a respective radio transceiver, all of the wireless transceiver of the same said communication frequency The communication collision avoidance method according to claim 9, wherein the communication collision avoidance method is set to a channel.   The communication collision avoidance method according to claim 11, wherein the predetermined threshold has different values for each of the communication frequency channel and the detection frequency channel.   The communication collision avoidance method according to any one of claims 9 to 15, wherein the signal transmission timing control operation is back-off control. A communication collision avoidance program in a wireless communication device having two or more antennas and a corresponding wireless transceiver,
On the computer,
At least one of the radio transceivers is set to a predetermined communication frequency channel, and at least one other radio transceiver of the radio transceiver is a detection frequency channel different from the communication frequency channel. A frequency channel determining step for determining the communication frequency channel and the detection frequency channel to be set to:
A radio wave detection step of detecting radio waves in the communication frequency channel and the detection frequency channel;
A radio wave state determination step for determining the state of the radio wave detected in the radio wave detection step;
A notification step of notifying the determination result obtained in the radio wave state determination step;
A transmission timing control step for performing signal transmission timing control for communication collision avoidance based on the notification by the notification step ;
The communication collision avoidance program causes the computer to further execute a step of confirming the number of other radio transceivers for which the communication frequency channel is not set, and if the number is 2 or more, the frequency channel In the determining step, if each of the upper and lower channels of the communication frequency channel is set to at least one other radio transceiver as the detection frequency channel and the number is 1, the frequency channel determining step And a communication collision avoidance program in which one of the upper and lower channels of the communication frequency channel is set as the detection frequency channel in another radio transceiver .   The communication collision avoidance program according to claim 17, wherein the determination result obtained in the radio wave state determination step is notified in the notification step when all the wireless transceivers are not transmitting data. In the radio wave state determination step, the computer further compares the radio wave intensity detected in the radio wave detection step with a predetermined threshold value; and
Radio wave detection that considers that the radio wave is detected when the strength of the radio wave is higher than the predetermined threshold, and that the radio wave is not detected when the strength of the radio wave is lower than the predetermined threshold A decision step;
If it is considered that at least one of the radio waves is detected in the radio wave detection determination step, a radio wave state determination step for determining that a radio wave state in the communication frequency channel and the detection frequency channel is busy is executed. ,
In the transmission timing control step, the signal transmission timing control is executed when the determination result notified in the notification step indicates that the radio wave state in the communication frequency channel and the detection frequency channel is not busy. The communication collision avoidance program according to claim 17 or 18.   A computer-readable recording medium on which the communication collision avoidance program according to any one of claims 17 to 19 is recorded.

Images