JP2011151444A - Radio data communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radio data communication system composed of two or more pieces of radio equipment for transmitting a data frame in a fixed cycle and a radio repeater, capable of operating the radio repeater to relay the data frame, when communication situation gets worse and one of the pieces of radio equipment starts resending of the data frame. <P>SOLUTION: The radio repeater monitors data frames transmitted in a fixed cycle by the pieces of radio equipment, and specifies a relay object. When communication situation gets worse and one of the pieces of radio equipment starts resending of the data frame, the radio repeater carries out relay transmitting of the data frame and the ACK frame of the relay object. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a wireless communication system including a plurality of wireless devices and a wireless relay device that perform data communication, and more particularly to a wireless data communication system that performs control and monitoring data communication of industrial machines at regular intervals.

  A system for controlling industrial equipment, for example, an industrial robot system has a controller for controlling the operation of the industrial robot, and also has a portable teaching device carried by an operator during teaching work, etc. The information communication between the teaching device and the controller is performed at regular intervals. The teaching device and the controller are connected by wire, and wireless communication is attempted in order to reduce the work burden on the teacher.

  In wireless communication, the communication status may deteriorate due to radio wave interference caused by external radio waves, blocking of a communication path due to obstacles, and the like. In addition, in a portable device such as the teaching device, the communication path may be interrupted depending on the work position and posture of the worker, and the communication status may deteriorate. As measures against this, in wireless communication, a method of retransmitting by a wireless device that has generally transmitted, and a method of relaying wireless communication by another wireless device are known (for example, see Patent Document 1).

In the communication system that performs data communication between a plurality of mobile terminals equipped with wireless communication means, the technique described in Patent Document 1 is a countermeasure when two wireless terminals cannot communicate directly.
Each wireless terminal includes a relay table, and performs relay communication based on the relay table. Specifically, as shown in FIG. 10, when relay transmission from the mobile terminal 110 to the mobile terminal 120 is difficult, specifically, relay is performed. When the number of packet retransmissions based on the table reaches a predetermined number, the mobile terminal 110 transmits a packet without designating a relay destination (for example, No. 0), and the mobile terminal 130 that has received the packet transmits the packet. A proxy relay method is open to the public. Further, in the communication system, an agent terminal that manages the relay table and a plurality of non-agent terminals that receive information on the relay table from the agent terminal form a group, and a new mobile terminal is the group The packet transmitted to and received from the agent terminal when entering the network (entry terminal) includes an agent search packet that the new mobile terminal transmits to confirm the presence of the agent terminal, and the agent terminal An agent search reply packet that is transmitted to inform the new mobile terminal of its presence, an entry request packet that the new mobile terminal transmits to request the agent terminal to join the group, and the agent terminal Allowed the new mobile terminal to join the group. Relay processing using the admission packet or the like more packets to be transmitted to have been made.

Japanese Patent Laying-Open No. 2006-25118 (paragraphs 0018 to 0022, FIG. 1)

  However, in the mobile radio communication system of Patent Document 1, when relay transmission is difficult, relay transmission is not performed until the number of packet retransmissions reaches a predetermined number. Therefore, a delay occurs between the start of packet retransmission and the predetermined number of times. There was a problem of doing. In addition, a packet that does not specify a destination is sent, and peripheral terminals that have received this packet respond to this and send relay packets one after another. This can increase the lifetime of relay packets and cause radio interference. There is. As a result, there is a problem of affecting communications performed at regular intervals. Also, in order to relay packets, a relay table is created between the entry terminal and the agent terminal using an agent search packet, an agent search response packet, an entry request packet, or an entry permission packet, and the processing is complicated. There was a problem that.

  The present invention has been made in view of such problems, and simplifies preparations until relay processing is performed. When the communication status deteriorates and the wireless device starts retransmission, the wireless device responds to a request from the wireless device. An object of the present invention is to provide a wireless communication system in which a wireless relay device relays and transmits a communication frame such as a data frame or an ACK frame.

In order to solve the above problem, the present invention is configured as follows.
The invention described in claim 1
In a wireless data communication system comprising a plurality of wireless devices and wireless repeaters that transmit data frames at regular intervals,
Based on the relay target table, the data frame to which the relay request is added is relay-transmitted, and only the ACK frame for the relay-transmitted data frame is relay-transmitted.
The invention described in claim 2
2. The wireless data communication system according to claim 1, wherein the wireless device adds the relay request to the data frame when retransmitting the data frame, and transmits an ACK frame for the data frame relayed when transmitting the ACK frame. It is characterized by adding identifiable information.
The invention according to claim 3
The wireless data communication system according to claim 1, wherein when the wireless relay device relays and transmits a data frame, the wireless relay device adds information that is a data frame to which a relay request is added by the wireless device based on a relay target table, In addition, when transmitting an ACK frame, information identifying whether it is an ACK frame for the data frame relayed or transmitted is added.
The invention according to claim 4
2. The wireless data communication system according to claim 1, wherein a data frame that is retransmitted by the wireless device or relay-transmitted by the wireless relay device adds a relay request and relay transmission information, and the wireless device that has received the data frame receives the data frame. Relay transmission information is added to an ACK frame transmitted or transmitted by the wireless relay device.
The invention described in claim 5
The wireless relay device according to claim 1 is characterized in that a relay target is selected from wireless devices that transmit data frames of a certain condition, and the relay target table is generated.
The invention described in claim 6
The predetermined condition of the data frame according to claim 5 is characterized in that the radio wave intensity is not less than a specified value and the transmission cycle of the data frame is not more than a specified value.

According to the invention described in claims 1 to 4,
When the wireless device starts to retransmit the data frame due to the deterioration of the communication status, the wireless relay device relays and transmits the data frame and the ACK frame, so that the data can be efficiently transmitted to the wireless device of the communication partner. The device can continue to communicate.

According to invention of Claim 5 thru | or 6,
Since the wireless relay device selects the wireless device to be relayed while actually monitoring the communication status of the data frame, preparation for relay processing can be easily performed without affecting communication.

1 is a configuration diagram of a wireless data communication system in an embodiment of the present invention. Example of communication frame format in an embodiment of the present invention 1 is a block diagram of a wireless relay device constituting a wireless data communication system in an embodiment of the present invention. Configuration diagram of relay target table of wireless data communication system in an embodiment of the present invention Communication frame relay processing sequence diagram in an embodiment of the present invention The flowchart figure of the frame reception process of the radio relay apparatus in the Example of this invention The flowchart figure of the timer processing of the radio relay device in the execution example of this invention The sequence diagram of the communication frame at the time of the monitor mode operation | movement of the radio relay apparatus in the Example of this invention The flowchart figure of the reception process at the time of monitor mode operation | movement of the radio relay apparatus in the Example of this invention Configuration diagram of a conventional mobile radio communication system

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that data frames and ACK frames are generally called communication frames.

  FIG. 1 is a configuration diagram of a wireless communication system using a wireless relay device according to an embodiment of the present invention. The wireless relay device 3 which is a feature of the present invention is installed at a position where a communication frame exchanged between the wireless device 1 and the wireless device 2 can be received. First, the operation outline of the present embodiment will be described below.

  FIG. 8 is a sequence diagram of a communication frame when the wireless relay apparatus according to the embodiment of the present invention operates in the monitor mode. A case where the communication state is good will be described with reference to FIG. In FIG. 8, the data frame is represented as “data”, and the ACK frame is represented as “ACK”. The monitor mode will be described later.

  The wireless device 1 transmits a data frame 421, and the wireless device 2 that has received the data frame 421 transmits an ACK frame 421. The wireless device 1 that has received the ACK frame 421 recognizes that the wireless device 2 has successfully transmitted the data frame 421. The wireless devices 1 communicate with each other at regular intervals (transmission cycles), and transmit a data frame 422 after a predetermined time has elapsed. The wireless device 2 that has received the data frame 422 transmits an ACK frame 422. The wireless device 1 that has received the ACK frame 422 recognizes that the wireless device 2 has successfully transmitted the data frame 422. Further, the wireless device 1 transmits a data frame 423 after a predetermined time has elapsed, and the wireless device 2 that has received the data frame 423 transmits an ACK frame 423. The wireless device 1 that has received the ACK frame 423 recognizes that the wireless device 2 has successfully transmitted the data frame 422. As described above, communication is normally performed with one ACK frame as one set for one data frame.

  Communication frames such as data frames and ACK frames transmitted / received between wireless devices are also received by the wireless relay device 3. When the communication status is good, the wireless devices 1 and 2 transmit the data frame to which the relay request at the wireless relay device 3 is not added, so the wireless relay device 3 only receives and does not perform relay transmission.

  Next, the case where the communication status deteriorates will be described with reference to FIG. It is assumed that the communication state deteriorates due to an obstacle or the like, and the wireless device 1 cannot receive the ACK frame from the wireless device 2 for the transmitted data frame. In this case, the wireless device 1 determines that the communication status has deteriorated because the ACK frame has not been returned within a predetermined time, and retransmits the data frame transmitted earlier by adding a relay request. The wireless relay device 3 that has received the data frame generates a relay data frame from the data frame based on the relay target table and relays it. The wireless device 2 that has received the relay data frame transmits an ACK frame to which a relay request indicating that the relay data frame is an ACK frame for the relay data frame that has been relayed is added. The ACK frame is relayed and transmitted by the wireless relay device 3, and the wireless device 1 recognizes that the data frame retransmitted by the wireless device 2 has been successfully received.

  FIG. 2 shows a communication frame format in the embodiment of the present invention. In FIG. 2, the communication frame format is the data link layer level of the OSI basic reference model. 2A shows a data frame, and FIG. 2B shows an ACK frame.

  In FIG. 2A, the control code indicates the type of frame such as whether the frame is a data frame or an ACK frame. The relay request flag is information that the wireless device requests relay transmission to the wireless relay device. When the flag is ON, that is, when a relay request is added, the wireless relay device relays and transmits a data frame. The relay transmission flag is a flag that is turned on when the wireless relay device relays and transmits the data frame. By referring to the relay transmission flag, it is possible to identify whether the data frame has been relay-transmitted. In the relay data frame shown in FIG. 1, the relay transmission flag is ON. The transmission source address and the transmission destination address store a unique address that each wireless device has in order to identify each wireless device, and it is possible to determine which wireless device sends a data frame to which wireless device. Data is passed to an upper layer (not shown), and FCS is a flag check sequence. In the present invention, the transmission source address and the transmission destination address of the data frame need only be able to identify which wireless device on the communication system, and do not specify the frame configuration order.

  The ACK frame shown in FIG. 2B includes an ACK frame control code, a relay transmission flag, a transmission source address, and an FCS. The source address and FCS are the same as in FIG. As for the relay transmission flag, the wireless device copies the relay transmission flag of the data frame. This makes it possible to identify whether the ACK frame is for a normal data frame or a relayed data frame. In the relay ACK frame shown in FIG. 1, the relay transmission flag is ON.

FIG. 3 is a block diagram of the wireless relay device in the embodiment of the present invention. In FIG. 3, the wireless relay device 3 includes an antenna 31, a wireless communication unit 32, a control unit 33, a volatile memory 34, a nonvolatile memory 35, an external interface unit 36, an input / output unit 37, a monitor mode operation switch 38, and the like. . 31 is an antenna for wireless communication, 32 is a wireless communication unit that receives a communication frame such as a data frame or an ACK frame and transmits a communication frame to be relayed. Measure radio field strength when receiving a frame. Reference numeral 33 denotes a control unit that executes relay processing according to the embodiment of the present invention, and includes a timer therein. Reference numeral 34 denotes a volatile memory for storing various timer counters such as a timer counter and a monitor mode operation timer (FIG. 9) and a relay target work table (FIG. 4). The various timer counters are updated using the timer of the control unit 33. Reference numeral 35 denotes a non-volatile memory that stores the relay target table (FIG. 4). The nonvolatile memory 35 stores a prescribed value of the radio field intensity and a prescribed value of the data frame transmission cycle.
Reference numeral 36 denotes an external interface unit that is connected to a peripheral device such as a personal computer by wire, and the external interface unit exchanges the specified value of the radio wave intensity, the specified value of the transmission period of the data frame, etc. during the monitor mode operation. The relay target table can be referred to and edited via an external interface unit.

  37 is an input / output unit, and 38 is a monitor mode operation switch. By operating the monitor mode operation switch, a specified value is set in the monitor mode operation timer in order to measure the monitor mode operation time, and the timer is started.

  By operating the monitor mode operation switch, the wireless relay device 3 executes the monitor mode operation for a predetermined time. Monitor mode operation refers to monitoring data frames that have a radio field intensity that exceeds the specified value and that is transmitted at a fixed period that is less than the specified value, and extracts the destination address of the data frame as the relay target address. The processing operation for generating the relay target table.

  FIG. 4 is a configuration diagram of the relay target table 50 according to the embodiment of this invention. In FIG. 4, the relay target table 50 is a collection of transmission source addresses of data frames. The transmission source address of the communication frame is assigned to each wireless device so as to be unique within the communication system.

  The relay target work table 55 is a work table for generating the relay target table 50, and the transmission source address of the data frame received during the monitor mode operation of the wireless relay device and the timer counter value when received are the timer counter. Stored in the previous value. The previous value of the timer counter is temporarily stored in order to determine whether the data frame is transmitted with a specified value for the cycle time.

  FIG. 5 is a sequence diagram when the wireless relay device in the embodiment of the present invention relays a data frame to be relayed. Assume that the address of the wireless device 1 is stored in the transmission source address 501 of the relay target table 50. In FIG. 5, the data frame is represented as “data” and the ACK frame is represented as “ACK”.

  In FIG. 5, a case where communication is normally performed will be described first. It is assumed that the address of the wireless device 1 is stored in the relay target table included in the wireless relay device 3. The wireless device 1 normally transmits data 401 in which both the relay request flag and the relay transmission flag are OFF to the wireless device 2. At this time, the data 401 is also received by the wireless relay device 3. The data 401 is a data frame having the address stored in the relay target table as a transmission destination address. However, since the relay request flag is OFF, the wireless relay device 3 only receives the data 401. The wireless apparatus 2 that has received the data 401 transmits the ACK 401 in which the relay transmission flag of the data 401 is copied, that is, the relay transmission flag is OFF. The ACK 401 is also received by the wireless relay device 3, but the ACK 401 is not relayed by the wireless relay device 3 because the relay transmission flag is OFF.

  Similarly, the wireless device 1 that transmits data frames at regular intervals transmits data 402 with the relay request flag set to OFF to the wireless device 2. In the data 402, since the relay request flag is OFF, the wireless relay device 3 only receives the data 402. The wireless device 2 that has received the data 402 transmits an ACK 402 whose relay transmission flag is OFF. The ACK 402 is also received by the wireless relay device 3, but the ACK 402 is not relayed by the wireless relay device 3 because the relay transmission flag is OFF.

  Next, a case where the communication status deteriorates due to an obstacle or the like between the wireless device 1 and the wireless device 2 will be described. The wireless device 1 transmits data 411 to the wireless device 2. At this time, it is assumed that the data 411 is received by the wireless relay device 3 but not received by the wireless device 2. The wireless device 1 waits for the ACK frame for a certain period of time, but has not received the ACK frame, and therefore retransmits the data 412 with the relay request flag set to ON. It is assumed that the data 412 is received by the wireless relay device 3 but not received by the wireless device 2. When the wireless relay device 3 receives the data 412 whose relay request flag is ON, the wireless relay device 3 waits for a predetermined time during which the wireless device 2 may transmit the ACK frame, and determines that the wireless device 2 does not transmit the ACK frame. Data 412a with the relay transmission flag set to ON is relay-transmitted. The data 412a is a data frame having the same contents as the data 412 except for the relay transmission flag and the FCS, but the codes are distinguished for convenience.

  The data 412a transmitted by the wireless relay device 3 is also received by the wireless device 1, but the wireless device 1 discards the data 412a because the transmission destination address of the data 412a is not its own address. The wireless device 2 that has received the data 412a transmits an ACK 412a obtained by copying the relay transmission flag of the data 412a. The wireless relay device 3 that has received the ACK 412a relays and transmits the ACK 412a because the relay transmission flag is ON, that is, since it is an ACK frame for the relay-transmitted data frame. At this time, the ACK 412a transmitted by the wireless relay device 3 is also received by the wireless device 2, but the wireless device 2 ignores the ACK 412a because it does not transmit a data frame.

  Further, it is assumed that the wireless device 1 transmits data 421 to the wireless device 2, and at this time, the data 411 is received by the wireless relay device 3 but not received by the wireless device 2. Since the wireless device 1 could not receive the ACK frame, the wireless device 1 retransmits the data 422 in which the relay request flag is turned on (the relay transmission flag is turned off). It is assumed that the data 422 is received by the wireless relay device 3 and also received by the wireless device 2. The wireless relay device 3 receives the data 412 whose relay request flag is ON, but waits for a predetermined time during which the wireless device 2 may transmit an ACK frame. The wireless device 2 that has received the data 422 whose relay transmission flag is OFF copies (remains OFF) the relay transmission flag and transmits ACK 422. The ACK 422 is also received by the wireless relay device 3, but the relay transmission flag is OFF and the ACK 422 transmitted within a predetermined time is not relayed by the wireless relay device 3.

As described above, the communication status between the wireless device 1 and the wireless device 2 deteriorates, the wireless device 1 retransmits the data frame with the relay request flag ON, and the wireless relay device 3 transmits the data frame. Since relay transmission is performed, the data frame retransmission time can be shortened.
In addition, when the ACK frame is normally transmitted for the data frame retransmitted by the wireless device, the wireless relay device does not perform the relay transmission of the data frame or the ACK frame. There is no.

  FIG. 6 is a flowchart of the frame reception process of the wireless relay device according to the embodiment of the present invention.

  This flowchart is executed by the control unit 31 of the wireless relay device 3 after every time until a ACK frame is returned after transmitting a data frame, every time a communication frame is received. First, it is determined whether the received frame is an ACK frame (S200). Since it is necessary to return the ACK frame within a predetermined time after receiving the data frame, the ACK frame is determined first. If it is not an ACK frame, it is determined whether it is a data frame (S201). If it is a data frame, it is checked whether the relay request flag of the data frame is ON (S202). If the relay request flag of the data frame is ON, the transmission source address of the data frame is read out, and the transmission source address is compared with the transmission source address of the relay target in the relay target table (S203). If so, data frame relay processing is performed (S204). In the data frame relay processing, processing such as turning on the relay transmission flag and recalculating the FCS is performed.

  When the received frame is an ACK frame, it is checked whether the relay transmission flag of the ACK frame is ON (S220). When the relay transmission flag of the ACK frame is ON, it is determined as an ACK frame for the data frame relayed and transmitted, and ACK frame relay processing is performed (S221). In the ACK frame transmission process, the received ACK frame is relayed and transmitted.

  FIG. 7 is a flowchart of timer processing of the wireless relay device in the embodiment of the present invention. This flowchart is executed by the control unit 31 of the wireless relay device 3 using a fixed-cycle timer in the control unit 31.

  The timer counter is updated (S400), and it is determined whether the monitor mode operation timer is running (S401). If the monitor mode operation timer is running, 1 is subtracted (S402). If the monitor mode operation timer obtained by subtracting 1 is 0 (S403), it is determined that the monitor mode operation has ended, and a relay target table is created. Specifically, the timer counter previous value saved together with the transmission source address of the relay target work table in the frame reception process during the monitor mode operation shown in FIG. 9, the timer counter updated in S401 (timer counter current value), If the difference is within the specified cycle time, it is determined that there is periodicity, and the source address of the relay target work table is copied to the source address of the relay target table (S404). This eliminates data frame reception that has occurred only once at the start of the monitor mode operation, and only the source address of the data frame that retains periodicity until the end of the monitor mode operation is relayed. Is for.

  FIG. 8 is a sequence diagram of communication frames when the wireless relay device according to the embodiment of the present invention operates in the monitor mode. Here, as in FIG. 5, the data frame is represented as “data” and the ACK frame is represented as “ACK”.

  The wireless device 1 normally transmits data 421 whose relay request flag is OFF to the wireless device 2. The wireless device 2 that has received the data 421 transmits an ACK 421 in which the relay request flag is OFF. The wireless device 1 transmits data frames with a fixed period and transmits data 422 and data 423, and the wireless device 2 transmits ACK 422 and ACK 423 for these data frames. During this time, the wireless relay device 3 monitors the periodicity of the data frame of the wireless device 1, calculates the cycle for a data frame having a radio field intensity equal to or higher than a specified value, and has a periodicity equal to or lower than the specified value. To determine. The wireless relay device 3 generates the relay target table with the transmission source address of the data frame having periodicity as a relay target until the end of the monitor mode.

  FIG. 9 is a flowchart of the frame reception process when the wireless relay device according to the embodiment of the present invention operates in the monitor mode.

  After the monitor mode operation switch of the wireless relay device 3 is operated, the control unit 31 of the wireless relay device 3 executes this flowchart every time a communication frame is received. Note that what is handled as a communication frame here is a frame having a radio field intensity equal to or higher than a specified value. This is because the wireless relay device 3 efficiently performs frame reception processing without processing a reception frame having only a noise level of radio wave intensity.

  First, it is determined whether the received frame is a data frame (S250). If it is a data frame, it is checked whether the transmission source address of the data frame is stored in the relay target work table of the volatile memory (S251). If the transmission source address is not stored, the transmission source address is relayed. The current value of the timer counter is saved as the previous value of the timer counter in the relay target work table at the source address of the target work table (S260). If the transmission source address has been saved, the previous value of the timer counter in the relay target work table is read, and the difference from the current value of the timer counter is calculated to calculate the cycle time (S252). If the calculated period time value is less than or equal to the specified period time value stored in the volatile memory (S253), it is determined that there is periodicity, and the current value of the timer counter is set to the previous value of the timer counter in the relay target work table. Save (S254). On the other hand, when the calculated value of the cycle time exceeds the specified value of the cycle time stored in the volatile memory (S253), it is determined that there is no periodicity (event type data), and the transmission source address of the relay target work table The previous value of the timer counter is cleared to 0 and deleted (S255). As a result, the relay processing target can be narrowed down to transmission data having a fixed period.

  In the present invention, an example of periodic data transmission by only the wireless device 1 has been shown. However, periodic data transmission by the wireless device 2 may be performed simultaneously, and the direction of data transmission is not limited.

1, 2 Wireless device 3 Wireless relay device 31 Antenna 32 Wireless communication unit 33 Control unit 34 Volatile memory 35 Non-volatile memory 36 External interface unit 37 Input / output unit 38 Monitor mode operation switch 50 Relay target table 501 Source address 55 Relay target Work table 551 (source address, previous value of timer counter)
110, 120, 130 Mobile terminal

Claims (6)

In a wireless data communication system composed of a plurality of wireless devices and wireless relay devices that transmit data frames at regular intervals,
A wireless data communication system, wherein a data frame to which a relay request is added is relay-transmitted based on a relay target table, and only an ACK frame for the relay-transmitted data frame is relay-transmitted.   2. The wireless data communication system according to claim 1, wherein the wireless device adds the relay request to the data frame when retransmitting the data frame, and transmits an ACK frame for the data frame relayed when transmitting the ACK frame. A wireless data communication system characterized by adding identifiable information.   The wireless data communication system according to claim 1, wherein when the wireless relay device relays and transmits a data frame, the wireless relay device adds information that is a data frame to which a relay request is added by the wireless device based on a relay target table, In addition, when transmitting an ACK frame, a wireless data communication system characterized by adding identifiable information to the relayed data frame as an ACK frame.   2. The wireless data communication system according to claim 1, wherein a data frame that is retransmitted by the wireless device or relay-transmitted by the wireless relay device adds a relay request and relay transmission information, and the wireless device that has received the data frame receives the data frame. A wireless data communication system, wherein relay transmission information is added to an ACK frame transmitted or transmitted by the wireless relay device.   2. The wireless data communication system according to claim 1, wherein the wireless relay device selects a relay target from wireless devices that transmit data frames of a certain condition, and generates the relay target table. 6. The wireless data communication system according to claim 5, wherein the predetermined condition is that the radio wave intensity is not less than a specified value and the transmission cycle of the data frame is not more than a specified value.

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