JP5555662B2 - Wireless communication apparatus, wireless communication system, and communication control method - Google Patents

Description

  The present invention relates to a wireless communication apparatus, a wireless communication system, and a communication control method, and more particularly to appropriate control according to a cause of a communication error.

  In wireless communication, generally, the greater the transmission power, the longer the reach of radio waves, and communication with distant radio stations becomes possible, but the range of radio interference increases. Conversely, the lower the transmission power, the shorter the reach of radio waves, and the narrower the range of radio wave interference, but the more communicable range is also narrowed.

  For this reason, transmission power control for selecting and transmitting suitable transmission power from a plurality of transmission power settings according to the communication quality and communication state of the transmission path such as signal attenuation, fading and noise, and a plurality of modulation methods Transmission speed control for selecting and communicating with a suitable system is known.

  Among them, as a conventional transmission power control method, for example, in the method described in Patent Document 1, the reception rate of a transmission signal for each frame is measured by a reception device, and the gain of the voltage control amplifier of the transmission unit is based on the result. Is variable.

  Regarding transmission rate control, the higher the transmission rate, the higher the probability of detecting errors on the receiving side, and the lower the transmission rate, the lower the probability of detecting errors on the receiving side. Here, the transmission rate is the ratio of the amount of information transmitted with respect to time. A large amount of information transmitted in a certain time is called a high transmission rate, and a small amount of information is transmitted in a certain time. The transmission rate is low. When the same amount of data is transmitted, the time required for transmission is shorter as the modulation method has a higher transmission rate, and the time required for transmission becomes longer as the modulation method has a lower transmission rate.

  As a conventional transmission rate control method, for example, in the method described in Patent Document 2, an error rate detection unit that detects an error rate based on the number of frames in which a determination result of an error correction code included in a received frame is NG and the number of received frames The transmission rate is selected from the transmission rate selection table based on the error rate detected by the error rate detection means.

  These methods described in Patent Document 1 and Patent Document 2 attempt to increase the reception rate by increasing the transmission power when the communication error occurs or decreasing the transmission rate.

JP 2001-36947 A JP 2000-101680 A

  However, the methods of Patent Literature 1 and Patent Literature 2 do not consider the cause of communication errors. That is, in these methods, transmission is controlled according to the reception state obtained as a result, but depending on the cause of the communication error, it may be desirable to perform transmission control from another viewpoint.

  For example, when an error due to radio wave interference occurs, it is considered effective to reduce the transmission power in order to prevent or suppress radio wave interference, but the conventional method is not controlled to reduce the transmission power in this case. .

  Also, when an error due to radio wave interference occurs, the carrier busy time during which radio waves are detected is longer than during normal times, so the transmission rate may be increased to shorten the carrier busy time. Although considered effective, the conventional method is not controlled to increase the transmission rate.

  Therefore, the present invention determines a cause of a communication error in a wireless communication system, a wireless communication apparatus, and a communication control method for selecting an appropriate setting from a plurality of transmission powers and a plurality of modulation schemes. It is an object of the present invention to provide a transmission power control unit and a transmission rate control unit that select an optimal setting according to the above factors.

  In order to solve the above-mentioned problem, in the present invention, a wireless communication device or a wireless communication device that performs wireless communication by specifying a communication partner and transmits a reception confirmation signal when receiving communication addressed to the own station. In the system, the wireless communication device sets the means for detecting the received power intensity of the signal received at its own station, the means for detecting the communication error, and the reception power intensity of the received signal when the communication error is detected. Communication error factor determination means that determines whether the cause of communication error is insufficient reception power or radio wave interference compared to a threshold that can be received without error. When the received signal strength is smaller than a possible threshold value, it is determined that there is a high possibility of a communication error due to insufficient received power, and communication recovery processing means for executing communication recovery processing is provided.

  Further, the communication recovery processing unit determines that the possibility of a communication error due to radio wave interference is high when the received signal strength is greater than a threshold that can be received without error, as determined by the communication error factor determination unit. Do not perform communication recovery action.

  The communication recovery measure means is a transmission power control unit when performing wireless communication, and the communication recovery measure is to increase the transmission power.

  The communication recovery processing means is a transmission speed control unit when performing wireless communication, and the communication recovery processing is to reduce the transmission rate.

  Further, it is determined that the signal is not jammed when receiving a signal not related to the communication of the local station, and a jamming notification function for notifying the transmitting station of the communication of the jamming and a possibility that the communication error factor is an error due to radio wave interference until the jamming notification is received. It is provided with a function for determining the possibility of interference so as not to determine that the value is high.

  In order to solve the above-described problem, in the present invention, in a wireless communication apparatus configured to identify a communication partner and execute wireless communication and send a reception confirmation signal when receiving communication addressed to the local station, Means for detecting the received power intensity of the received signal, means for detecting a communication error, and when a communication error is detected, the received power intensity of the received signal is compared with a preset threshold that can be received without error. As a result of the determination by the communication error factor determination means for determining whether the cause of the communication error is insufficient reception power or radio wave interference and the determination by the communication error factor determination means, the received signal strength is smaller than a threshold that can be received without error. In this case, it is determined that there is a high possibility of a communication error due to insufficient reception power, and the transmission power control unit that increases the transmission power when performing wireless communication and the determination by the communication error factor determination unit, If the received signal strength is smaller than the threshold that can be received without error set, the transmission speed control unit determines that the possibility of a communication error due to insufficient received power is high, and reduces the transmission rate when performing wireless communication; When receiving a signal not related to the data communication of the local station, it is determined that the signal is disturbed, and the transmission power that does not cause interference is estimated from the interference notification function that notifies the transmission station of the signal of the interference and the reception power intensity of the interference notification. Interference-free transmission power estimation function and transmission power that enables transmission power that does not cause estimated interference by performing control by the transmission power control unit when the transmission power that does not cause estimated interference is less than the transmission power that can be communicated A switching function for switching so as to implement the control by the transmission speed control.

  In order to solve the above-mentioned problem, in the present invention, a communication error is detected in a communication control method in which a communication partner is identified and wireless communication is performed and a reception confirmation signal is sent when communication is received to the local station. When the signal is detected, the received power intensity of the received signal is compared with a threshold that can be received without a preset error to determine whether the cause of the communication error is a lack of received power or radio wave interference. When the received signal strength is smaller than the receivable threshold, it is determined that there is a high possibility of a communication error due to insufficient received power, and the reception recovery processing is executed. The received signal strength is lower than the threshold that can be received without a preset error. If it is larger, it is determined that there is a high possibility of a communication error due to radio wave interference, and communication recovery processing is not executed.

  In order to solve the above-mentioned problems, in the present invention, in a communication control method for specifying a communication partner and performing wireless communication and receiving a reception confirmation signal when receiving communication addressed to the local station, If a communication error is detected by not receiving a reception confirmation signal from the other station within a certain time after transmission, and if communication fails continuously, the transmission power is increased as a communication recovery measure and succeeds continuously. In this case, the transmission power is reduced, and at the timing when the communication has changed from a communication failure to a communication success, the received power intensity of the received signal is compared with a threshold that can be received without a preset error. When it is determined whether there is a shortage or radio wave interference, and if the received signal strength is less than the threshold value that can be received without errors in advance, it is determined that there is a high possibility of a communication error due to insufficient reception power, and wireless communication is performed. Increasing the transmission power when the received signal strength is greater, it is determined that there is a high possibility of a communication error due to radio interference, to maintain the transmission power, or reduced.

  In order to solve the above-mentioned problems, in the present invention, in communication control in which a communication partner is specified and wireless communication is performed and a reception confirmation signal is sent when receiving communication addressed to the own station, When a communication error is detected because the reception confirmation signal from the other station is not obtained within a certain time after transmission, and when communication fails continuously, the signal transmission rate is lowered as a communication recovery measure, and the communication succeeds continuously. If the signal transmission rate is increased, the received signal strength of the received signal is compared with a threshold that can be received without a preset error at the timing when the communication is changed from a communication failure to a communication success. If the received signal strength is lower than the threshold value that can be received without errors set in advance, it is determined that there is a high possibility of a communication error due to insufficient received power, and wireless communication is performed. Maintaining the signal transmission rate, or raised, it is determined that there is a high possibility of a communication error due to radio interference when the received signal strength is large, reduce the signal transmission rate.

  In a wireless communication system, a wireless communication apparatus, and a communication control method for selecting a suitable setting from a plurality of transmission powers and a plurality of modulation schemes, the cause of a communication error is determined, and the optimum according to the cause of the communication error It is possible to provide a transmission power control means and a transmission speed control means for selecting a proper setting.

The block diagram which shows the radio | wireless communication apparatus which concerns on one Embodiment of this invention. The figure which shows the process in the frame reception process part 104 when a received frame is a data frame. The figure which shows the process in the frame reception process part 104 in case a received frame is an ACK frame. FIG. 6 is a diagram for explaining the operation content of the media access control unit 105. The flowchart which shows the transmission power determination procedure by communication error factor estimation. The block diagram which shows the radio | wireless communication apparatus provided with the interference determination part and the interference notification part. Configuration diagram showing a wireless communication apparatus provided with an interference suppression type transmission rate control unit The flowchart which shows the transmission rate determination procedure by communication error factor estimation. The figure which shows the radio | wireless communication apparatus provided with the interference suppression means switching part.

  The basic idea of the present invention is to measure the received signal strength, and when a communication error occurs, compare this with a threshold that can be received without error to distinguish between reception power shortage and radio wave interference as a cause of communication error, and receive A communication recovery procedure is executed when power shortage is the cause.

  As a form of realization of the idea of the present invention, a single wireless communication device, a wireless communication system in which a plurality of wireless communication devices are combined, or a communication control method can be realized.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a configuration diagram showing a wireless communication apparatus according to the first embodiment of the present invention. In actual application, a plurality of wireless communication devices are installed to constitute a wireless communication system.

  In the first embodiment, transmission power is adjusted as a communication recovery procedure to be executed when a shortage of received power is the cause.

  The wireless communication apparatus 101 includes an antenna 102, a wireless reception processing unit 103, a frame reception processing unit 104, a media access control unit 105, an interference suppression type transmission power control unit 106, a communication error factor estimation unit 107, a wireless A transmission processing unit 108. Note that each processing unit described above is realized by an analog or digital electronic circuit, firmware executed by a CPU incorporated in an LSI, or the like according to mounting.

  When transmitting data to be transmitted, the wireless communication device 101 is classified as either a transmission device that is a transmission source or a reception device that is a transmission destination. That is, the wireless communication device 101 has both the components of the transmission device and the reception device. For example, data to be transmitted is transferred in the order of wireless communication device A → wireless communication device B → wireless communication device C. When viewed from the wireless communication device A, the wireless communication device B operates as a reception device, and when viewed from the wireless communication device C, the wireless communication device B operates as a transmission device. In the following description, processing on the reception device side and processing on the transmission device side when focusing on transmission of data to be transmitted will be described.

  In the following description, processing on the receiving device side will be described first, and then processing on the transmitting device side will be described.

  In the processing on the receiving device side, the radio reception processing unit 103 receives radio signals received via the antenna 102 and performs reception processing including frequency conversion, filtering, direct detection, AD conversion, symbol timing synchronization detection, and demodulation processing. carry out.

  The demodulation process is performed only when symbol timing synchronization is detected, and the frame 1031 after the demodulation process and the received signal strength 1032 representing the received strength of the radio signal are output to the frame reception processing unit 104. In addition, a radio signal is always input to the radio reception processing unit 103 except during transmission, and either when the synchronization is detected or when the received signal strength is a certain value or more, for example, −62 dBm or more. If it is satisfied, it is determined that the carrier is busy, and if it is less than a certain value, it is determined that the carrier is idle, and the carrier sense result 1033 is output to the media access control unit 105.

  The frame reception processing unit 104 appropriately processes the received frame based on the frame control information stored in the received frame 1031 if no error is detected after the error check, and receives an error if an error is detected. Discard the frame. Here, the details of the processing of the frames other than the data frame and the ACK frame notifying the communication success are omitted.

  Hereinafter, processing in the frame reception processing unit 104 when the reception frame 1031 is a data frame will be described with reference to FIG.

  First, it is confirmed whether the receiving station address of the received data frame matches the address of the wireless communication apparatus 101. If they do not match, the received frame is discarded. If they match, the received data 1041 is extracted by removing the header of the received frame or the like, and the received data is output to the upper layer of the wireless communication apparatus 101 or the connected wired network 90. In addition, in order to return an ACK frame, which is a data frame reception response, to the data frame transmission source, the transmission station address of the data frame is transferred to the media access control unit 105 as the ACK frame transmission destination address 1042.

  Next, processing in the frame reception processing unit 104 when the received frame is an ACK frame will be described with reference to FIG.

  It is confirmed whether the receiving station address of the received ACK frame matches the address of the wireless communication apparatus 101. If they do not match, the received frame is discarded. If they match, the fact that the ACK frame has been received is output to the media access control unit 105 as a signal 1043. At this time, the received signal strength 1032 obtained from the wireless reception processing unit 103 is transferred to the media access control unit 105 together with the reception of the ACK frame (signal 1043).

  Next, processing on the transmission device side will be described.

  When the transmission data 901 is input from the upper layer of the wireless communication apparatus 101 or the connected wired network 90 as illustrated in FIG. 4, the media access control unit 105 creates a transmission signal 1051.

  The transmission signal 1051 is formed by a transmission source address ADS, a transmission destination address ADR, a header HDR composed of control information such as a frame type, and a data frame DF to which an error detection code is added, and performs transmission control.

  The transmission control determines whether to start the transmission process based on the carrier sense result 1033 input from the wireless reception processing unit 103. That is, when the data frame DF is generated and the carrier sense result 1033 is continuously set for the set time, the transmission processing is determined to be started. In other cases, the transmission process is not started.

  The set time differs depending on the access control method. For example, the set time of CSMA / CA (Carrier Sense Multiple Access / Collision Avoidance), which is a random access control method, is composed of a fixed transmission interval time and a back-off time that is a random time.

  When it is determined that the transmission process is started, the generated transmission signal 1051 is output to the wireless transmission processing unit 108, and the wireless transmission processing unit 108 transmits the transmission signal 1051 via the antenna 102.

  Here, when the operation of the wireless communication apparatus 101 on the side that has received the transmission signal 1051 is followed, the function on the side of the reception processing unit works as shown in FIG. That is, in this case, since the data frame is received, the wireless communication apparatus 101 having the address match returns an ACK frame.

  In response to this result, the reception processing unit side of the wireless communication apparatus 101 on the side of the first transmission functions as shown in FIG. That is, in this case, since an ACK frame is received, the address match is confirmed, the ACK frame 1043 is received, and a response signal is given to the media access control unit 105.

  In this case, the media access control unit 105 of the transmitting wireless communication apparatus 101 monitors the ACK frame 1043. Specifically, it is determined whether or not an ACK frame 1043 is obtained within a certain time after transmission signal 1051 transmission (data frame transmission).

  If the ACK frame 1043 cannot be received from the frame reception processing unit 104 even after a predetermined time has elapsed after transmission signal 1051 transmission (data frame transmission), a communication error is recognized and retransmission processing is performed. At this time, the destination address ADR and communication error notification (signal 1052) are output to the interference suppression type transmission power control unit 106.

  On the other hand, when it is input that the ACK frame 1043 is received from the frame reception processing unit 104 within a certain time after the transmission signal 1051 is transmitted (data frame transmission), the communication success is recognized and the transmission signal 1051 is transmitted. Complete. At this time, the destination address ADR, the communication success notification, and the received signal strength 1032 are output to the interference suppression transmission power control unit 106 as a signal 1053.

  Although the description has been made before and after, in the previous description, when the data frame is received, the wireless communication device 101 having the address match returns an ACK frame. This function is realized by generating an ACK frame addressed to the ACK frame transmission destination address 1042 and outputting it to the wireless transmission processing unit 108 according to transmission control when an ACK frame transmission destination address is input in FIG. .

  The interference suppression type transmission power control unit 106 receives a failure signal (a signal related to a destination address ADR and a communication error) 1052 or a success signal (transmission) from the media access control unit 105 as a series of operation results related to transmission and reception described above. The previous address ADR, communication success notification and received signal strength 1032) 1053 are obtained.

  Further, when the communication failure state changes and the communication success is notified, the interference suppression type transmission power control unit 106 transfers the received signal strength 1032 input from the media access control unit 105 to the communication error factor estimation unit 107. Then, the cause of the previous communication error is estimated in the communication error factor estimating unit 107.

  As a result of the factor estimation, if the communication error factor estimation unit 107 determines that there is a high possibility of an error due to insufficient reception power, the transmission error for the destination address ADR is increased, and the communication error factor estimation unit 107 If it is determined that there is a high possibility of an error due to radio wave interference, the transmission power for the destination address is maintained or the transmission power is reduced.

  When the received power intensity is input from the interference suppression type transmission power control unit 106, the communication error factor estimation unit 107 performs estimation of the communication error factor. For example, this is performed as follows. First, here, a “threshold capable of receiving without error” is set in advance, and when the received signal strength is smaller than this, it is determined that there is a high possibility of a communication error due to insufficient received power, and the received signal is determined from the threshold. When the strength is high, it is determined that there is a high possibility of an error due to radio wave interference, and the determination result is input to the interference suppression transmission power control unit 106.

  As is clear from the above, in the first embodiment, the interference suppression type transmission power control unit 106 is used as a communication recovery processing method executed when reception power shortage is the cause in the present invention.

  When a frame is input from the media access control unit 105, the wireless transmission processing unit 108 performs transmission processing including modulation processing, DA conversion, frequency conversion, filtering, and power amplification, and receives a radio signal from the antenna 102. Send. In the power amplification, the amount of power amplification is controlled according to the transmission power value input from the interference suppression type transmission power control unit 106.

  According to the embodiment of the present invention, the transmission power control according to the communication error factor is executed by the cooperative operation of the interference suppression type transmission power control unit 106 and the communication error factor estimation unit 107. Hereinafter, this concept will be described in detail with reference to the flowchart of FIG. 5 showing a transmission power determination procedure based on communication error factor estimation according to an embodiment of the present invention.

  In the flowchart shown below, the determination is advanced using two indexes. One of them is the “threshold capable of receiving without error” described above, and the other is a communication error flag. Here, the communication error flag is a flag that is set to High when a communication error occurs. When the communication error flag is High, it indicates that a communication error occurred during the previous communication.

In the description of the flowchart, the following may be considered as communication states that occur in communication between a plurality of wireless communication apparatuses.
A: State in which communication succeeds continuously B: State in which communication fails continuously C: State in which the state has shifted from the failed state to the successful state D: State in which the state has shifted from the successful state to the failed state E: State in which success and failure are repeated Therefore, in the following description, the flow of the flowchart of FIG. 5 in each communication state will be described.

A: Successful communication in this case In this case, processing proceeds along the line indicated by A in FIG. First, in step S101, the communication success / failure notifications 1052 and 1053 input from the media access control unit 105 are confirmed. Since the communication is successful, the process proceeds to step S102 to check the communication error flag. Here, since communication has succeeded continuously, the communication error flag is Low, and the process proceeds to step S103. In step S103, 1 is added to the number of continuous communication successes. Next, in the determination in step S106, if the number of successful continuous communications is equal to or greater than a preset transmission power down threshold, the number of successful continuous communications is reset to 0 in step S107, and the transmission power is reduced in step S108. Note that when the number of successful continuous communications is less than a preset transmission power down threshold, the transmission power is maintained.

  Through a series of these processes, the transmission power is maintained at the minimum value at which communication is possible in a state where communication has succeeded continuously.

B: State where communication fails continuously In this case, processing proceeds along the line indicated by B in FIG. First, in step S101, the communication success / failure notifications 1052 and 1053 input from the media access control unit 105 are confirmed. Since communication is unsuccessful, the process proceeds to step S105 to check the communication error flag. Here, since continuous communication has failed, the communication error flag is High, and the process proceeds to Step S110. In step S110, the transmission power is increased.

  Through a series of these processes, the transmission power is continuously increased in a state in which communication has failed continuously, and approaches a region where stable communication is possible. If communication fails continuously, the transmission power may not be increased for each failure, but may be increased by a plurality of consecutive failures.

C: State shifted from the failed state to the successful state In this case, the process proceeds along the line indicated by C in FIG. First, in step S101, the communication success / failure notifications 1052 and 1053 input from the media access control unit 105 are confirmed. Since communication is successful this time, the process proceeds to step S102, and a communication error flag is confirmed. Here, since the previous communication has failed, the communication error flag is High, and the process proceeds to step S104. In step S104, the communication error flag is set to Low due to the current communication success.

  By the way, as described above, the interference suppression type transmission power control unit 106 communicates the received signal strength 1032 input from the media access control unit 105 when the communication failure state is changed and the communication success is notified. This is transferred to the error factor estimation unit 107. In step S114, the received signal strength 1032 is compared with a receivable threshold.

  In this comparison determination, when the received signal strength is smaller than the “threshold capable of receiving without error”, it can be determined that there is a high possibility of a communication error due to insufficient received power. In other words, the previous communication failure is considered to be caused by low received signal strength.

  On the other hand, when the received signal strength is greater than the threshold, it can be determined that there is a high possibility of an error due to radio wave interference. That is, since the previous communication failure occurred in an environment where the received signal strength is large, there is a possibility of an error due to radio wave interference. As an error due to radio wave interference, in a wireless communication system including a plurality of wireless communication apparatuses, signal collision, movement of an obstacle, and the like can be considered in addition to the case where communication frequencies used by each other interfere.

  If it is determined that there is a high possibility of a communication error due to insufficient reception power, the process proceeds to step S110 to increase transmission power. If it is determined that there is a high possibility of a communication error, the process proceeds to step S103 of line A described above, and processing is performed in a state where communication succeeds continuously.

  In addition, when succeeding next time following this state, the process proceeds according to the line A thereafter. Further, when it fails next time, the next process D is performed.

D: State shifted from the successful state to the failed state In this case, the process proceeds along the line indicated by D in FIG. First, in step S101, the communication success / failure notifications 1052 and 1053 input from the media access control unit 105 are confirmed. Since this time communication is unsuccessful, the process proceeds to step S105 to check the communication error flag. Here, since the previous communication was successful, the communication error flag is Low, and the process proceeds to step S111. In step S111, the communication error flag is set to High due to the current communication failure, and then the number of continuous communication successes is set to 0 in step S112. In addition, transmission power is maintained.

  Note that if this state continues to fail next time, the process proceeds according to line B thereafter. When succeeding next time, the process of the previous C is performed.

E: State of repeating success and failure In this case, the processes of C and D are performed alternately, but step S114 is performed in the process of line C. Among these, it is determined whether the cause of the communication failure is a communication error due to insufficient received power or an error due to radio wave interference.

  According to the present embodiment described above, the cause of the communication error is determined, and the optimum transmission power is selected according to the cause of the communication error. If there is a high probability of a communication error due to insufficient reception power when a communication error occurs, increase the transmission power to improve the probability of successful communication, and if there is a high probability of error due to radio wave interference, maintain the transmission power. Alternatively, it is possible to suppress radio wave interference by reducing transmission power.

  If the communication control method in FIG. 5 is arranged, the transmission power is increased as a communication recovery measure when continuously failing, and the transmission power is reduced when succeeding continuously. Prevent interference in communication systems. In addition, at the timing when the failure changes to success, the cause of the previous failure is determined and necessary measures appropriate for each are executed.

  The necessary measures are to restore the stable communication by increasing the transmission power when the received signal strength is low, and to maintain the transmission power when the received signal strength is high, or to reduce it when sufficiently secured. That is.

  In the case of the present invention, radio wave interference is considered to be the cause when a communication error occurs while the received signal strength is sufficient. In these transient phenomena that are likely to be recovered in a short time, the transmission power is basically maintained or reduced. For this reason, it is possible to prevent interference or radio wave interference as a result of increasing the transmission power as in the prior art.

  A second embodiment of the present invention will be described with reference to the drawings.

  In the second embodiment, the determination of the cause of the communication error is not always performed, but is started in a state where radio interference is occurring. In other words, the communication error factor is not determined to be highly likely to be an error due to radio wave interference until interference is detected.

  FIG. 6 is a configuration diagram illustrating a wireless communication apparatus including an interference determination unit 302 and an interference notification unit 303 according to an embodiment of the present invention.

  The wireless communication device 301 in FIG. 6 has a configuration in which the interference determination unit 302 and the interference notification unit 303 are added to the wireless communication device 101 in FIG. 1. By adding the configuration, the media access control unit 105 and the frame reception processing unit are added. 104 and the processing contents of the communication error factor estimation unit 107 are different. The processing contents of the other units are the same as in FIG.

  The interference determination unit 302 determines whether or not the frame received and processed by the frame reception processing unit 104 is a frame related to the data communication of the own station, that is, whether or not it is an interference.

  If it is addressed to its own station or addressed to the other station that it has made data communication with, it is determined as a frame (communication target frame) related to its own data communication. If it is not addressed to the own station or to the other station to which the own station has performed data communication, it is determined that the frame is a non-target frame (communication non-target frame) not related to the data communication of the own station.

  In short, the communication target frame is a frame related to the own station, and the communication non-target frame is a frame not related to the own station. The non-communication target frame, which is a frame not associated with the own station, is a frame that interferes with the own station. When it is determined as an obstructed frame, the transmission station address is input to the obstruction notification unit 303 as an obstruction notification destination address 3021.

  When receiving the interference notification destination address 3021 from the interference determination unit 302, the interference notification unit 303 generates an interference notification frame 3031 having the interference notification destination address 3021 as a receiving station in a data frame format, and sends it to the media access control unit 105. input.

  When receiving the interference notification frame 3031 from the interference notification unit 303, the media access control unit 105 outputs the interference notification frame 3031 to the wireless transmission processing unit 108 according to transmission control in the same manner as the data frame.

  On the other hand, in the frame reception processing unit 104 of the wireless communication apparatus that has received the transmission signal including the interference notification frame 3031, when the interference notification frame 3031 is received, the communication error factor estimation unit 107 receives the interference notification frame. This is notified by a signal 1044.

  The communication error factor estimation unit 107 determines that all the factors of the communication error are insufficient in received power intensity until the signal 1044 notifies that the interference notification frame has been received. However, the estimation of the cause of the communication error is widely determined at the stage after receiving notification that the interference notification frame has been received. That is, by comparing and confirming the received power intensity with the receivable threshold value, it is determined whether the possibility of insufficient received power intensity is high or the possibility of radio wave interference is high.

  According to the present embodiment described above, the possibility of radio wave interference is considered as a cause of communication error only when radio wave interference is possible. By grasping whether or not radio wave interference can occur, it is possible to reduce the probability of erroneous determination of an error due to radio wave interference and improve the communication success probability.

  A third embodiment of the present invention will be described with reference to the drawings.

  In the third embodiment, the transmission speed (transmission rate) is adjusted as a communication recovery procedure to be executed when reception power shortage is the cause. The adjustment of the transmission speed (transmission rate) is performed by the interference suppression type transmission speed control unit 402 provided in the wireless communication apparatus shown in FIG.

  The wireless communication device 401 in FIG. 7 has a configuration in which the interference suppression transmission power control unit 106 of the wireless communication device 101 in FIG. 1 is replaced with an interference suppression transmission rate control unit 402. The processing content of 108 is different. The processing contents of the other units are the same as in FIG.

  The interference suppression type transmission rate control unit 402 receives a failure signal (a signal related to a destination address ADR and a communication error) 1052 or a success signal (transmission) from the media access control unit 105 as a series of operation results related to transmission and reception described above. The previous address ADR, communication success notification and received signal strength 1032) 1053 are obtained.

  The interference suppression type transmission rate control unit 402 transfers the received signal strength 1032 input from the media access control unit 105 to the communication error factor estimation unit 107 when the communication failure state is changed and the communication success is notified. Then, the cause of the previous communication error is estimated in the communication error factor estimating unit 107.

  As a result of the factor estimation, if the communication error factor estimation unit 107 determines that there is a high possibility of an error due to insufficient reception power, the communication error factor estimation unit 107 reduces the transmission rate for the destination address ADR. If it is determined that there is a high possibility of an error due to radio wave interference, the transmission rate for the destination address is maintained or the transmission rate is increased.

  The communication error factor estimation unit 107 estimates the communication error factor when the received power intensity is input from the interference suppression type transmission rate control unit 402. For example, this is performed as follows. First, here, a “threshold capable of receiving without error” is set in advance, and when the received signal strength is smaller than this, it is determined that there is a high possibility of a communication error due to insufficient received power, and the received signal is determined from the threshold. When the strength is high, it is determined that there is a high possibility of an error due to radio wave interference, and the determination result is input to the interference suppression transmission rate control unit 402.

  When a frame is input from the media access control unit 105, the wireless transmission processing unit 108 performs transmission processing including modulation processing, DA conversion, frequency conversion, filtering, and power amplification, and receives a radio signal from the antenna 102. Send. In the power amplification, the amount of power amplification is controlled according to the transmission rate value input from the interference suppression type transmission rate control unit 402.

  According to the present invention, the transmission rate control according to the cause of the communication error is executed by the cooperative operation of the interference suppression type transmission rate control unit 402 and the communication error factor estimation unit 107. Hereinafter, this concept will be described in detail with reference to a flowchart showing a transmission rate determination procedure based on communication error factor estimation according to an embodiment of the present invention shown in FIG.

  In the flowchart shown below, the determination is advanced using two indexes. One of them is the “threshold capable of receiving without error” described above, and the other is a communication error flag. Here, the communication error flag is a flag that is set to High when a communication error occurs. When the communication error flag is High, it indicates that a communication error occurred during the previous communication.

In the description of the flowchart, the following may be considered as communication states that occur in communication between a plurality of wireless communication apparatuses.
A: State in which communication succeeds continuously B: State in which communication fails continuously C: State in which the state has shifted from the failed state to the successful state D: State in which the state has shifted from the successful state to the failed state E: State in which success and failure are repeated Therefore, in the following description, the flow of the flowchart of FIG. 8 in each communication state will be described.

A: Successful communication in this case In this case, processing proceeds along the line indicated by A in FIG. First, in step S 501, communication success / failure notifications 1052 and 1053 input from the media access control unit 105 are confirmed. Since the communication is successful, the process proceeds to step S502 to check the communication error flag. Here, since communication has succeeded continuously, the communication error flag is Low, and the process proceeds to step S503. In step S503, 1 is added to the number of continuous communication successes. Next, in the determination in step S506, if the number of successful continuous communications is equal to or greater than a preset transmission rate up threshold, the number of successful continuous communications is reset to 0 in step S507, and the transmission rate is increased in step S508. If the number of successful continuous communications is less than a preset transmission rate up threshold, the transmission rate is maintained.

  Through a series of these processes, the transmission rate is maintained at the maximum value in a state where the communication is succeeded continuously.

B: State where communication fails continuously In this case, processing proceeds along the line indicated by B in FIG. First, in step S 501, communication success / failure notifications 1052 and 1053 input from the media access control unit 105 are confirmed. Since the communication is unsuccessful, the process proceeds to step S505 to check the communication error flag. Here, since continuous communication has failed, the communication error flag is High, and the process proceeds to step S510. In step S510, the transmission rate is lowered.

  By a series of these processes, the transmission rate is continuously reduced in a state where communication fails continuously, and it is brought closer to an area where stable communication is possible. In the case where communication fails continuously, the transmission rate may not be lowered for each failure, but may be lowered by a plurality of consecutive failures.

C: State shifted from failure state to success state In this case, processing proceeds along the line indicated by C in FIG. First, in step S 501, communication success / failure notifications 1052 and 1053 input from the media access control unit 105 are confirmed. Since communication is successful this time, the process proceeds to step S502, and a communication error flag is confirmed. Here, since the previous communication has failed, the communication error flag is High, and the process proceeds to step S504. In step S504, the communication error flag is set to Low due to the current communication success.

  By the way, as described above, the interference suppression type transmission rate control unit 402 communicates the received signal strength 1032 input from the media access control unit 105 when the communication failure state is changed and the communication success is notified. This is transferred to the error factor estimation unit 107. In step S514, the received signal strength 1032 is compared with a receivable threshold.

  In this comparison determination, when the received signal strength is smaller than the “threshold capable of receiving without error”, it can be determined that there is a high possibility of a communication error due to insufficient received power. In other words, the previous communication failure is considered to be caused by low received signal strength.

  On the other hand, when the received signal strength is greater than the threshold, it can be determined that there is a high possibility of an error due to radio wave interference. That is, since the previous communication failure occurred in an environment where the received signal strength is large, there is a possibility of an error due to radio wave interference. As an error due to radio wave interference, in a wireless communication system including a plurality of wireless communication apparatuses, signal collision, movement of an obstacle, and the like can be considered in addition to the case where communication frequencies used by each other interfere.

  If it is determined that there is a high possibility of a communication error due to insufficient received power, the process proceeds to step S510 to lower the transmission rate. If it is determined that there is a high possibility of a communication error, the process proceeds to step S503 of the line A described above, and processing is performed in a state where communication is continuously successful.

  In addition, when succeeding next time following this state, the process proceeds according to the line A thereafter. Further, when it fails next time, the next process D is performed.

D: State shifted from the successful state to the failed state In this case, the process proceeds along the line indicated by D in FIG. First, in step S 501, communication success / failure notifications 1052 and 1053 input from the media access control unit 105 are confirmed. Since this time communication is unsuccessful, the process proceeds to step S505 to check the communication error flag. Here, since the previous communication was successful, the communication error flag is Low, and the process proceeds to step S511. In step S511, the communication error flag is set to High due to the current communication failure, and then the number of successful continuous communications is set to 0 in step S512. In addition, the transmission rate is maintained.

  Note that if this state continues to fail next time, the process proceeds according to line B thereafter. When succeeding next time, the process of the previous C is performed.

E: State of repeating success and failure In this case, the processes of C and D are performed alternately, but step S514 is performed in the process of line C. Among these, it is determined whether the cause of the communication failure is a communication error due to insufficient received power or an error due to radio wave interference.

  When the concept of the communication control method of FIG. 8 is arranged, the transmission rate is lowered as a communication recovery measure when continuously failing, and the transmission rate is raised when succeeding continuously. In addition, at the timing when the failure changes to success, the cause of the previous failure is determined and necessary measures appropriate for each are executed.

  The necessary measures are to restore the stable communication by reducing the transmission rate when the received signal strength is low, and to maintain the transmission rate when the received signal strength is high or to increase it when it is sufficiently secured. It is.

  According to the present embodiment described above, the cause of the communication error is determined, and the optimum transmission speed is selected according to the cause of the communication error. If there is a high possibility of a communication error due to insufficient reception power for the modulation method when a communication error occurs, improve the communication success probability by lowering the transmission rate, and if there is a high possibility of error due to radio wave interference, By maintaining the transmission rate or increasing the transmission rate, it is possible to suppress radio wave interference.

  A fourth embodiment of the present invention will be described with reference to the drawings.

  In the fourth embodiment, either the transmission speed (transmission rate) or the transmission power is adjusted as a communication recovery procedure to be executed when the shortage of reception power is the cause.

  In the embodiment of FIG. 9, a wireless communication apparatus provided with an interference suppression means switching unit is shown. The wireless communication apparatus 601 in FIG. 9 is configured by adding an interference suppression transmission speed control unit 402, an interference-free transmission power estimation unit 602, and an interference suppression unit switching unit 603 to the wireless communication apparatus 301 in FIG. The processing contents of the frame reception processing unit 104 differ depending on the situation. The processing contents of other units are the same as those in FIG. 6, and the processing contents of the interference suppression type transmission rate control unit 402 are the same as those in FIG.

  When receiving the interference notification frame, the frame reception processing unit 104 transfers the received signal strength 1032 to the interference-less transmission power estimation unit 602.

  The interference-less transmission power estimation unit 602 estimates transmission power 6021 that does not cause interference from the reception power intensity 1032 of the interference notification frame input from the frame reception processing unit 104, and outputs the estimated transmission power 6021 to the interference suppression switching unit 603.

  When an estimated transmission power value 6021 that does not cause interference is input, the interference suppression switching unit 603 obtains transmission power that can be communicated with each destination address from the interference suppression type transmission power control unit 106 and gives interference. Compare with no estimate 6021 of transmit power.

  When the estimated transmission power value 6021 that does not impede is less than or equal to the transmission power value at which communication is possible, it is determined that radio wave interference can be prevented or suppressed by the transmission power, and interference suppression type transmission power control is performed.

  When the estimated transmission power value 6021 that does not impede exceeds the transmittable transmission power value, it is determined that it is difficult to prevent or suppress radio wave interference by the transmission power, and interference suppression type transmission rate control is performed.

  According to the present embodiment described above, the optimum transmission power and transmission speed are selected from the relationship between the transmission power that can be communicated and the transmission power that does not cause radio wave interference. When the transmission power prevents or suppresses radio wave interference, the transmission power is controlled so as to suppress the radio wave interference, and when the transmission power prevents or is difficult to suppress, transmission is performed to suppress the radio wave interference. By controlling the speed, radio wave interference can be further suppressed.

  In the present embodiment, in a wireless communication system, a wireless communication apparatus, and a communication control method for selecting an appropriate setting from a plurality of transmission powers and a plurality of modulation schemes, a cause of a communication error is determined, and a communication error It is possible to provide a transmission power control unit and a transmission rate control unit that select an optimum setting according to a factor, which has an effect of improving a communication success probability and suppressing radio wave interference. In particular, it is effective when applied to a wireless communication system for industrial use that requires high reliability and real-time performance, and its industrial value is great.

  In addition, this invention is not limited to the said embodiment as it is, In an implementation stage, it can embody by modifying a component in the range which does not deviate from the summary. Moreover, various inventions can be formed by appropriately combining a plurality of constituent elements 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.

101: Radio communication device 102: Antenna 103: Radio reception processing unit 104: Frame reception processing unit 105: Media access control unit 106: Interference suppression type transmission power control unit 107: Communication error factor estimation unit 108: Radio transmission processing unit

Claims (12)

In a wireless communication device that identifies a communication partner and executes wireless communication, and sends a reception confirmation signal when receiving communication addressed to its own station.
Means for detecting the received power intensity of the signal received by the own station;
Means for detecting a communication error;
Communication error factor that determines whether the cause of the communication error is insufficient reception power or radio wave interference by comparing the received power intensity of the received signal with a preset threshold that can be received without error when a communication error is detected A determination means;
If the received signal strength is smaller than a threshold that can be received without errors set in advance as determined by the communication error factor determining means, it is determined that there is a high possibility of a communication error due to insufficient received power, and communication recovery processing is executed. Communication recovery action means to
An interference notification function for determining interference when receiving a signal not related to the communication of the local station, and notifying the transmission station of the communication;
A wireless communication apparatus , comprising: a disturbance possibility determination function that prevents the communication error factor from determining that there is a high possibility of an error due to radio wave interference until an interference notification is received . The wireless communication device according to claim 1, wherein
The communication recovery processing unit determines that the possibility of a communication error due to radio wave interference is high when the received signal strength is greater than a threshold that can be received without error, as determined by the communication error factor determination unit. A wireless communication apparatus that does not execute communication recovery processing. The wireless communication device according to claim 1 or 2,
The communication recovery processing means is a transmission power control unit for performing wireless communication, and the communication recovery processing is to increase transmission power. The wireless communication device according to claim 1 or 2,
The communication recovery processing means is a transmission speed control unit for performing wireless communication, and the communication recovery processing is to reduce a transmission rate. In a wireless communication device that identifies a communication partner and executes wireless communication, and sends a reception confirmation signal when receiving communication addressed to its own station.
Means for detecting the received power intensity of the signal received by the own station;
Means for detecting a communication error;
Communication error factor that determines whether the cause of the communication error is insufficient reception power or radio wave interference by comparing the received power intensity of the received signal with a preset threshold that can be received without error when a communication error is detected A determination means;
When it is determined by the communication error factor determination means that the received signal strength is smaller than a preset threshold that can be received without error, it is determined that there is a high possibility of a communication error due to insufficient reception power, and wireless communication is performed. A transmission power control unit that increases the transmission power of
When it is determined by the communication error factor determination means that the received signal strength is smaller than a preset threshold that can be received without error, it is determined that there is a high possibility of a communication error due to insufficient reception power, and wireless communication is performed. A transmission speed control unit that lowers the transmission rate of
When receiving a signal not related to the data communication of the own station, it is determined that the signal is disturbed, and a disturbance notification function for notifying the transmission station of the signal of the interference,
The interference-less transmission power estimation function that estimates the transmission power that does not cause interference from the received power intensity of the interference notification,
When the transmission power that does not cause the estimated interference is equal to or lower than the transmission power that can be communicated, control by the transmission power control unit is performed, and when the transmission power that does not cause the estimated interference exceeds the transmission power that can be communicated, the transmission speed control A wireless communication device comprising a switching function for switching so as to perform control according to. In a wireless communication system configured by arranging a plurality of wireless communication devices configured to perform wireless communication by specifying a communication partner and receive a reception confirmation signal when receiving communication addressed to the own station,
Each of the wireless communication devices is
Means for detecting the received power intensity of the signal received by the own station;
Means for detecting a communication error;
Communication error factor that determines whether the cause of the communication error is insufficient reception power or radio wave interference by comparing the received power intensity of the received signal with a preset threshold that can be received without error when a communication error is detected A determination means;
If the received signal strength is smaller than a threshold that can be received without errors set in advance as determined by the communication error factor determining means, it is determined that there is a high possibility of a communication error due to insufficient received power, and communication recovery processing is executed. Communication recovery action means to
A wireless communication system , comprising: a possibility of interference determination that prevents the communication error factor from determining that the possibility of an error due to radio wave interference is high until an interference notification is received . The wireless communication system according to claim 6 , wherein
The communication recovery processing unit determines that the possibility of a communication error due to radio wave interference is high when the received signal strength is greater than a threshold that can be received without error, as determined by the communication error factor determination unit. A wireless communication system characterized by not performing a communication recovery procedure. The radio communication system according to claim 6 or 7 ,
The communication recovery processing means is a transmission power control unit when performing wireless communication, and the communication recovery processing is to increase transmission power. According to claim 7 or claim 8 Symbol mounting of the wireless communication system,
The communication recovery processing means is a transmission speed control unit for performing wireless communication, and the communication recovery processing is to reduce a transmission rate. In a wireless communication system in which a wireless communication is performed by specifying a communication partner, and a reception confirmation signal is sent when receiving communication addressed to the own station.
Means for detecting the received power intensity of the signal received by the own station;
Means for detecting a communication error;
Communication error factor that determines whether the cause of the communication error is insufficient reception power or radio wave interference by comparing the received power intensity of the received signal with a preset threshold that can be received without error when a communication error is detected A determination means;
When it is determined by the communication error factor determination means that the received signal strength is smaller than a preset threshold that can be received without error, it is determined that there is a high possibility of a communication error due to insufficient reception power, and wireless communication is performed. A transmission power control unit that increases the transmission power of
When it is determined by the communication error factor determination means that the received signal strength is smaller than a preset threshold that can be received without error, it is determined that there is a high possibility of a communication error due to insufficient reception power, and wireless communication is performed. A transmission speed control unit that lowers the transmission rate of
When receiving a signal not related to the data communication of the own station, it is determined that the signal is disturbed, and a disturbance notification function for notifying the transmission station of the signal of the interference,
The interference-less transmission power estimation function that estimates the transmission power that does not cause interference from the received power intensity of the interference notification,
When the transmission power that does not cause the estimated interference is equal to or lower than the transmission power that can be communicated, control by the transmission power control unit is performed, and when the transmission power that does not cause the estimated interference exceeds the transmission power that can be communicated, the transmission speed control A wireless communication system comprising a switching function for switching so as to perform control according to. In a communication control method for specifying a communication partner and performing wireless communication, and sending a reception confirmation signal when receiving communication addressed to the own station.
A communication error is detected by not receiving a reception confirmation signal from the other station within a certain time after transmission to the other station.
If communication fails continuously, increase the transmission power as a communication recovery measure,
If it succeeds continuously, reduce the transmission power,
At the timing when communication failure turns into communication success, the received power intensity of the received signal is compared with a threshold that can be received without a preset error to determine whether the cause of the communication error is insufficient received power or radio wave interference. ,
If the received signal strength is smaller than the threshold that can be received without errors set in advance, it is determined that there is a high possibility of a communication error due to insufficient reception power, and the transmission power when performing wireless communication is increased.
A communication control method characterized by determining that a possibility of a communication error due to radio wave interference is high when the received signal strength is high, and maintaining or reducing transmission power. In a communication control method for specifying a communication partner and performing wireless communication, and sending a reception confirmation signal when receiving communication addressed to the own station.
A communication error is detected by not receiving a reception confirmation signal from the other station within a certain time after transmission to the other station.
If communication fails continuously, reduce the signal transmission rate as a communication recovery measure,
If it succeeds continuously, raise the signal transmission rate,
At the timing when communication failure turns into communication success, the received power intensity of the received signal is compared with a threshold that can be received without a preset error to determine whether the cause of the communication error is insufficient received power or radio wave interference. ,
If the received signal strength is smaller than a threshold that can be received without errors set in advance, it is determined that there is a high possibility of a communication error due to insufficient received power, and the signal transmission rate when performing wireless communication is maintained or increased,
A communication control method characterized by determining that a possibility of a communication error due to radio wave interference is high when the received signal strength is high, and lowering the signal transmission rate.

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