JPH0775425B2 - Wireless communication method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a communication technique between a fixed terminal and a mobile terminal using radio, and more particularly, to moving beyond a radio zone of a single fixed radio station. The present invention relates to a wireless communication technique for ensuring communication with a mobile wireless station that operates.

[Prior art]

For example, in the case of automatically controlling an overhead crane moving in a large warehouse such as a steel mill or a factory, it is necessary to secure communication between a ground terminal provided in an operation room or the like and an on-board terminal provided in the overhead crane.

Although wireless communication is an effective method for ensuring communication between a fixed terminal and a moving terminal in this way, the moving range of the mobile terminal does not necessarily fall within the wireless zone of the wireless device connected to the fixed terminal. Not necessarily. In this case, it is conceivable to increase the output of the wireless device to expand the wireless zone, but there are various problems such as effects on other devices, and this is rarely allowed.

Therefore, conventionally, an inductive wireless system is often adopted as a means for ensuring this type of communication. In the case of the above-mentioned overhead crane, this is a method of laying a leaky waveguide along the rail of the overhead crane and installing a wireless device on the overhead crane to ensure communication. According to this, since the leaky waveguide is installed at a position extremely close to the wireless device on the overhead crane, the power required for wireless communication can be very small, and there is almost no effect on other devices.

However, this conventional inductive wireless system requires a leaky waveguide and a work for laying the leaky waveguide, so that there is a problem that the cost related to equipment and the cost required for maintenance thereof are very large. For the same reason, updating and extending the leaky waveguide also requires a large cost, so it is easy to change or extend the route of a moving object such as a crane, or change the operating frequency due to an increase in communication content. I can't.

In the communication method disclosed in Japanese Patent Application Laid-Open No. 60-143037, when communication is performed between a plurality of wireless base stations connected to a center device and a large number of mobile wireless devices, when transmitting from the center to the mobile wireless devices, A mobile wireless device that originates a call from a base station sends a response, the wireless base station that receives this response informs the center of the response information and its reception level, and the center receives the response and the reception level is high. Is set for communication with the mobile wireless device. It is speculated that this communication method can improve the above-mentioned problems of the guided wireless system to some extent.

[Problems to be Solved by the Invention]

However, since the center sets a radio base station with a high response level (high reception level) from the mobile radio to communicate with the mobile radio, the reception level is apt to fluctuate depending on the situation, so the response is received. The processing rationale of collecting reception levels from all the selected radio base stations and selecting the radio base station with the highest reception level is complicated, and until the communication channel between the mobile radio and one radio base station is established. Takes time.

[Means for Solving the Problems]

The present invention allows communication between a fixed first terminal and a moving second terminal to be performed by a first wireless device and a second wireless device connected to the first terminal.
When securing via the second wireless device connected to the terminal, a plurality of first wireless devices are used to provide a service area including the moving range of the second terminal beyond the wireless zone of the single first wireless device. In the wireless communication method to be set: When transmitting from the first terminal to the second terminal, a free communication channel is selected from a plurality of channels by the carrier sense method, and the selected communication channel is designated via the control channel. Each first wireless device sequentially makes a call origination to make an outgoing call, and the second wireless device first responds via the communication channel designated by the call first received via the control channel, whereby the first wireless device first responds. The first wireless device that originated the call received by the two wireless devices is set as the first wireless device for communication.

[Action]

Since the plurality of first wireless devices sequentially perform the above-mentioned call transmission through the control channel and the second wireless device waits for reception on the control channel, the first of the call transmissions that is close to the second wireless device. The one that one wireless device emitted is the second
When the second wireless device receives the first call origination, it switches to the communication channel designated by the second wireless device and responds, so that the second call origination is performed by the second wireless device. A communication channel is set up between the second wireless device that was not received and the first wireless device that originated the call originally received by the second wireless device.

Therefore, it is automatically determined which one of the plurality of first wireless devices is set for communication, and the communication channel is immediately established as soon as the second wireless device receives the call origination. No post-call processing for selecting one is required, and there is substantially no delay time from the reception of the call origination by the second wireless device to the setting of the communication channel.

In addition, since the communication channel is selected from a plurality of channels by the carrier sense method, the adaptability or flexibility to the number and arrangement of the first wireless devices, the change or extension of the movement route of the second wireless device, the change of the used frequency, or the like. The cost of equipment changes required for changes or expansion is low.

Other objects and features of the present invention will become apparent from the following description of the embodiments with reference to the drawings.

〔Example〕

FIG. 1 shows the configuration of an overhead crane control system for carrying out the present invention as an example.

In FIG. 1, reference numeral 1 denotes a factory building, which is provided with an overhead crane 2 which reciprocates in the longitudinal direction. The operation room of the factory building 1 is equipped with a ground control terminal 10 connected to a host computer (not shown), to which wireless modems R1, R2 and R3 fixed at predetermined positions in the factory building 1 are connected. ing. These radio modems R1, R2 and R
3 wireless zones are indicated by r1, r2 or r3 in the figure,
A service area covering the entire area of the factory building 1 is allowed, allowing duplication. Further, the crane 2 is equipped with an on-board control terminal 20, to which a wireless modem C1 fixed on the crane 2 is connected. These wireless modems
R1, R2 or R3 and the wireless modem C1 ensure wireless communication between the ground control terminal 10 and the ground control terminal 20 for transmitting and receiving data necessary for controlling the crane 2.

The hardware configuration of the embodiment apparatus will be described with reference to FIG.

As shown here, the ground control terminal 10 is mainly composed of a microprocessor (hereinafter referred to as CPU) 11, and its bus line has a main memory 12, a timer & counter module 13,
I / O interface circuit (hereinafter simply abbreviated as I / O) 14 to 1
7, keyboard terminal KB1, printer PTR, floppy disk FD1 and hard disk HD1 etc. are connected. The I / O14 is connected to the wireless modem R1 via the wired modems M1a and M1b, the I / O15 is connected to the wireless modem R2, and the I / O16 is connected to the wireless modem R3 via the wired modems M3a and M3b. A host computer (not shown) is connected to the I / O 17 via the wired modem M0.

Further, the on-board control terminal 20 is mainly composed of the CPU 21, and the bus line thereof includes the main memory 22, the timer & counter module 23, the I / O 24 to which the wireless modem C1 is connected, the keyboard terminal KB2, the floppy disk FD2 and the drawing. Although omitted, controlled elements including various actuators and drivers are connected.

As shown in FIG. 3, the software configuration of the device of this embodiment is such that upper-layer transmission control for controlling transmission between the host computer and the logic device on the ground side and transmission control between the logic device and each wireless modem are performed. The lower-level transmission control is performed, the wireless communication control is performed to control the wireless section between the ground side and the upper side, and the local transmission control is performed to control the controlled element on the upper side. Further, the transmission control includes upper path control for selecting and analyzing an identification code with the host computer, and upper data link control for managing the transmission procedure, order, etc., and the lower transmission control is for each wireless modem. Selection and analysis of identification codes between R1 to R3, or lower path control that performs selection of receiving modem, zone crossing, zone tracking, etc., which will be described later, and
The local transmission control is composed of three lower-order data link controls for managing the transmission procedure, order, etc., and the local transmission control is for lower-order data link control for managing the transmission procedure, order, etc. of the wireless modem C1, and
The input control is performed to select and analyze an identification code with a controlled element mounted on the crane 2, exchange data, convert an input / output format, and the like. Further, the logic device emulates a command from the host computer or performs conversion of the data format transmitted / received to / from the host computer. In wireless communication control, selection of communication channel, line connection and connection for each wireless modem are performed. Performs disconnection and error control. The wireless modem used in this embodiment has 9 channels including one control channel. In wireless communication control, the communication channel is selected by the carrier sense method, and the line connection and disconnection are identified by the identification code of each wireless modem. The error control is performed by the ARQ method.

A specific example will be described with reference to the flowcharts shown in FIGS. 4a, 4b, and 4c.

First, see FIG. 4a. This flow shows each control operation when the power is turned on and when there is no communication.
Is in the position of P ₀ in FIG. 1, that is, in the wireless zone of the on-board wireless modem C 1 and the terrestrial wireless modem R 1.

When the power of each of the wireless modems R1 to R3 and C1 is turned on, an initial process for initializing the input / output, the buffer memory and the like is performed in each wireless communication control.

When the ground control terminal 10 is turned on, a transmission initial process for setting an initial state of transmission is performed in the lower path control. Here, the lower-layer transmission program and constants are initialized, and the registered wireless modems R1 to R3
Start the line connection process of lower data link control corresponding to. Thereby, in the lower data link control, after instructing the line connection to the corresponding radio modems R1 to R3, the response is received and the process is terminated. Thus, in this embodiment, signals are exchanged between different systems in an interactive manner.

In each of the wireless modems R1 to R3, when the line connection is instructed, the own station identification code is registered in the wireless communication control, the power of the wireless unit is turned on, the communication channel is set to the control channel C-CH, and the standby state is set. To do.

Further, when the power of the onboard control terminal 20 is turned on, in the lower data link control, a transmission initial process for initializing the transmission state and a registration process for registering tracking data are performed to set a reception waiting state. In this line connection process, the wireless modem C1 is instructed to connect to the line, and in the registration process tracking data including the identification code assigned to the onboard control terminal 20 and the partner station identification code are transferred to the wireless modem C1 and registered. Instruct.

In the wireless communication control, the wireless modem C1 registers its own station identification code and turns on the power of the wireless unit in response to the line connection instruction, sets the communication channel to the control channel C-CH, and transfers in response to the registration instruction. The tracking data and the partner station identification code thus set are set in the buffer memory, and then the standby state is set.

On the other hand, in the lower path control of the ground control terminal 10, after performing the transmission initial process, the zone tracking process is set to start and the reception waiting state is set. However, after this n seconds, that is, the radio modem R1 and Wait a sufficient time for the standby state to be set in the wireless communication control of C1,
Start the zone tracking process. In the zone tracking process, first, the wireless modem R1 is instructed to execute the polling process. This allows the wireless modem R1
Now, perform the polling process in wireless communication control,
The wireless modem C1 is inquired about the presence or absence of communication data via the control channel C-CH. Correspondingly, the wireless modem C1 transmits the tracking data set in the buffer memory to the wireless modem R1 via the control channel C-CH, so that the wireless modem R1 receives this and controls the data on the ground. Transfer to the lower path control system of the terminal 10.

This zone tracking processing is performed in m-second cycles when there is no communication by timer management. Crane 2 in the meantime
Moves and the wireless zone where the wireless modem C1 exists changes,
When the polling by the wireless modem R1 becomes impossible, the other wireless modems R2 and R3 are instructed to execute the polling process in order, and the wireless modem receiving the tracking data from the wireless modem C1 at that time is switched to. In this way, in the lower route control of the ground control terminal 10, the wireless zone where the wireless modem C1 exists, that is, the position of the crane 2 is tracked.

FIG. 4b shows that when the crane 2 moves from the position P _{0 to} the position P _{2 in} FIG. 1 during transmission from the ground control terminal 10 to the onboard control terminal 20, that is, the onboard radio modem C1 is on the ground. Each control operation when moving from the wireless zone of the wireless modem R1 to the wireless zone of R2 is shown.

When the host computer gives an instruction to transmit to the crane 2, the logic unit of the ground control terminal 10 reads it and starts the transmission process, and stores the transmission data from the host computer in the main memory 12 (see FIG. 2). Then, the transmission request process of the lower route control is activated.

In the transmission request process, the line establishing process is activated at predetermined time intervals in order from the lower data link control corresponding to the wireless modem R1.

When the corresponding wireless modem is instructed to make a call in the line establishing process of each lower data link control, each wireless modem selects a free communication channel by the carrier sense method in the wireless communication control and sets the control channel C-CH. Call through, specify the selected communication channel, and set the reception waiting on that channel.

On the upper side of the device, the wireless modem C1 is on standby on the control channel C-CH, and switches to the communication channel specified by the first received call. In this case, since the crane 2 is in the position P ₀ , the communication channel Di specified by the call of the wireless modem R1
-Switch to CH. Therefore, after this, the wireless modem R2
Or the call from R3 will not be received.

When the call is received by the wireless modem C1, the wireless communication control activates the line establishing process of the lower data link control. Here, since the call response is instructed to the wireless modem C1, the wireless modem C1 issues a response signal via the channel Di-CH.

The radio modem R1 receives the response signal from the radio modem C1 and notifies the lower communication channel control on the ground side of the communication channel Di-CH to be used. The lower-level data link control on the ground side confirms the line establishment, stores the communication status such as the in-communication flag, the wireless modem used, the used communication channel, etc., and activates the transmission waiting request process of the lower-level route control and executes the transmission process. .

In the low-order path control, in the transmission waiting request processing, the transmission waiting processing of the low-order data link control corresponding to the unused wireless modems, that is, the wireless modems R2 and R3 is activated.
As a result, in the lower data link control corresponding to the radio modems R2 and R3, the transmission data from the host computer is read from the main memory 12 (see FIG. 2), transferred to each corresponding radio modem R2 or R3, and the channel Di -Instruct to wait for CH transmission. As a result, in the wireless modems R2 and R3, the transmission data is BCH coded (random error correction code), format-converted into a block format and stored in the buffer memory, and the communication channel is set to Di-CH and a transmission wait is set. .

After that, the radio modems R2 and R3 stand by in a transmission waiting state, and when receiving the transmission request signal from the radio modem C1, activate the partner station response acceptance process of the lower path control.

In the lower data link control corresponding to the wireless modem R1, in the transmission process, the transmission data from the host computer is read from the main memory 12 and transferred to the wireless modem R1 to instruct the transmission. As a result, in the wireless modem R1, the transmission data is converted into a BCH code (random error correction code), converted into a block format, stored in the buffer memory, and transmitted by the hybrid ARQ method via the channel Di-CH for each block. Start.

Here, communication by the hybrid ARQ method will be described with reference to FIG. In FIG. 5, the left side shows the transmission data block on the transmitting side, and the right side shows the transmission request signal on the receiving side. The transmission data block consists of 8 blocks, and the transmission request signal is NAK (Negative Acknowledge) block N.
It consists of o. and the block number that you want to send next.

First, in No. 1, 2, 3, 4, 5, 6, 7 and 8 from the transmitting side
The transmission data block consisting of the block of is transmitted. The receiving side receives this and performs error correction / error detection. At this time, if there is an error in the blocks of Nos. 3, 5, and 6, the NAK blocks No. 3, 5, and 6, from the receiving side in
In addition, block No.9,10,11,12 that you want to send next
Issue a request to send signal containing 13 and 13. In response to this, the sending side sends a send data block consisting of No. 3, 5, 6, 9, 10, 11, 12, and 13 blocks, but the receiving side makes an error in receiving the No. 10 block. Occurs, the NAK block No. 10 and a transmission request signal including the block Nos. 14, 15, 16, 17, 18, 19 and 20 to be transmitted next are issued.

When the transmission side cannot receive the transmission request signal issued from the reception side, the next transmission data block is transmitted as if the previously transmitted reception data block was correctly transmitted, as in. In this case, since No. 16 is the final block, the transmission data block consisting of No. 14, 15 and 16 blocks is transmitted. Even if the receiving side correctly receives the transmitted data block at this time, since the block of No. 10 has not been received yet, at NAK block No.
10 and the block No. 17, 18, 19, which you want to send next
Issue a transmission request signal including 20, 21, 22 and 23. In response to this, when the No. 10 block is transmitted from the transmitting side, the receiving side has correctly received up to the final block, so an ACK (acknowledge) signal is issued and data transmission is terminated.

During communication, the crane 2 moves to the position P ₁ in Fig. ₁ , and the on-board wireless modem C1 moves to the wireless zone r1 of the ground wireless modem R1.
If it goes out of the range, the wireless modem R1 cannot receive the transmission request signal from the wireless modem C1. That is, the wireless modem R1
There is no response to the transmitted data block sent from the to the wireless modem C1.

In the wireless communication control of the wireless modem R1, the communication state is monitored from the dialogue between the transmission and reception by the hybrid ARQ method, and when the response to the transmission of the transmission data block N times is not obtained, the transmission start request processing of the lower path control is activated. . In the transmission start request processing of the lower-layer route control, the wireless modem C1 at that time
Request to start transmission to the wireless modem R2 that has received the transmission request signal from the wireless modem R2, and start the transmission waiting process of the lower data link control corresponding to the wireless modem R1.

As a result, the transmission data block corresponding to the transmission request signal from the wireless modem R2 is immediately transmitted from the wireless modem R2, so that smooth zone crossing is completed without interrupting the communication.

After that, the wireless modem C1 issues an ACK signal to the wireless modem R2 when the transmission data from the host computer is normally received up to the final block, and also converts the format of the received data and transfers it to the onboard control terminal 20. In the wireless modem R2, the communication is terminated when the ACK signal is received from the wireless modem C1, the standby state by the control channel C-CH is set, and the post-transmission processing of the lower data link control is activated. In this post-transmission processing, the buffer memory of the wireless modem R2 is cleared, and the lower path control transmission completion processing is moved. In the lower path control, the transmission waiting release processing of the lower data link control corresponding to the radio modems R1 and R3 is activated in the transmission completion processing. This allows wireless modem R1
In the lower data link control corresponding to R3 and R3, the corresponding wireless modem R1 or R3 is instructed to cancel the transmission wait. As a result, in the radio modems R1 and R3, the buffer memory is cleared, the transmission waiting state is released, and the standby state by the control channel C-CH is set.

On the other hand, the onboard control terminal 20 confirms that the transmission data from the host computer is normally received in the reception process of the lower data link control, instructs the wireless modem C1 to terminate the communication, and controls the lower data link control. The data stored in the buffer memory is stored in the main memory 22 (see FIG. 2), and the input / output control reception process is started. In the input / output control reception process, data format conversion and control of the corresponding controlled terminal are performed. Further, the wireless modem C1 thereafter changes the communication channel to the control channel C.
-Set to CH to set the standby status.

After the communication is terminated, the above-mentioned zone tracking processing is started in the m-second cycle by the timer management in the lower route control.

FIG. 4c shows that when the crane 2 moves from the position P _{0 to} the position P _{2 in} FIG. 1 during transmission from the onboard control terminal 20 to the ground control terminal 10, that is, the onboard radio modem C1 is on the ground. Each control operation when moving from the wireless zone of the wireless modem R1 to the wireless zone of R2 is shown.

When transmission from the controlled terminal to the host computer is instructed, transmission data from the controlled terminal is stored in the main memory 22 (see FIG. 2) in input / output control of the onboard control terminal 20,
Start the line establishment process of lower data link control.

In this line establishing process, since the on-board wireless modem C1 is instructed to make a call, the wireless modem C1 selects a free communication channel by the carrier sense method in the wireless communication control and sets the control channel C-CH. Make a call via
Specify the selected communication channel and set the reception waiting on that channel. On the terrestrial side, the wireless modems R1 to R3 are on standby on the control channel C-CH, and the wireless modem that receives the call issued from the wireless modem C1 switches to the communication channel specified by the call in the wireless communication control, The first-come-first-served reception process of the route control is activated and the communication channel used is notified. Here, since the crane 2 is at the position P ₀ , the call from the wireless modem C1 is received by the wireless modem R1, and the communication channel Dj-CH designated by the call is switched to the first-come-first-served receiving process of the lower-layer route control. to start. In the first-come-first-served accepting process, the line establishment process of the corresponding lower data link control is started only for the first-initiated accepting wireless modem, and the communication status such as the in-communication flag, the wireless modem used, and the used communication channel is set. Store. In this case, the line establishing process of the lower data link control corresponding to the wireless modem R1 is activated. Thereafter, in the lower path control, reception waiting request processing is performed, and the reception waiting processing of the lower data link control corresponding to the wireless modems that do not specify the communication channel Dj-CH, that is, the wireless modems R2 and R3 is activated. . As a result, the wireless modems R2 and R3 set the communication channel to Dj-CH and set the waiting for reception.

After that, the radio modems R2 and R3 stand by in a reception waiting state, and when receiving the transmission data block from the radio modem C1, activate the partner station response acceptance processing of the lower path control.

In the line establishing process performed by the lower-order data link control on the terrestrial side, the wireless modem R1 issues a call response, so that the wireless modem R1 issues a response signal via the channel Dj-CH.

The wireless modem C1 receives the response signal from the wireless modem VR1 and the line is established.

In the line establishing process performed by the lower data link control on the upper side of the machine, when the establishment of the line is confirmed, the transmitting process is executed to read the transmission data from the main memory 22, and the data is transferred to the wireless modem C1 to instruct the transmission. As a result, in the wireless modem C1, the transmission data is stored in the buffer memory, and the transmission by the hybrid ARQ method is started via the channel Dj-CH as in the above.

During communication, the crane 2 moves to the position P ₁ in Fig. ₁ , and the on-board wireless modem C1 moves to the wireless zone r1 of the ground wireless modem R1.
If it goes out of the range, the wireless modem R1 cannot receive the transmission data block from the wireless modem C1. That is, there is no response to the transmission request signal sent from the wireless modem R1 to the wireless modem C1.

In the wireless communication control of the wireless modem R1, the communication state is monitored from the dialogue between the transmission and reception by the hybrid ARQ method, and when the response to the transmission of the transmission request signal N times is not obtained, the reception start request processing of the lower route control is activated. , The reception completion block number is notified, the format of the normal reception block data is converted (the abnormal reception block data is replaced with the initial value), and the data is transferred to the ground control terminal 10. In the reception process of the lower data link control corresponding to the wireless modem R1 of the ground control terminal 10, the data other than the initial value among the data stored in the buffer memory of the lower data link control is stored in the main memory 12 (see FIG. 2). Store.

In the reception start request processing of the lower path control, the reception completion block No. is notified to the radio modem R2 which is receiving the transmission data block from the radio modem C1 at that time, and the reception start is requested and the radio modem R1 is requested. The reception waiting process of the corresponding lower data link control is started. This allows
Since the wireless modem R2 immediately starts reception, smooth zone crossing is completed without interrupting communication.

After that, the wireless modem R2 issues an ACK signal to the wireless modem C1 when the transmission data from the onboard control terminal 20 is normally received up to the final block, and converts the format of the normally received block data (reception The block data that does not exist is replaced with the initial value) and is transferred to the ground control terminal 10. In the wireless modem C1, from the wireless modem R2
When the ACK signal is received, the communication is terminated, the standby state by the control channel C-CH is set, and the post-transmission processing of the lower data link control is activated. In this post-transmission processing, the buffer memory of the wireless modem C1 is cleared.

On the other hand, the ground control terminal 10 confirms that the transmission data from the onboard control terminal 20 is normally received in the reception processing of the lower data link control compatible with the wireless modem R2, and confirms that the wireless modem
The R2 is instructed to terminate the communication, and the data other than the initial value among the data stored in the buffer memory for the lower data link control is stored in the main memory 12 (see FIG. 2).
At this time, the reception completion processing of the lower path control is started and the reception processing of the logical unit is started.

In the reception completion processing of the lower-level route control, the wireless modem R1 and
The reception waiting release processing of the lower data link control corresponding to R2 is activated, the reception waiting of the radio modems R1 and R3 is released, and the standby state by the control channel C-CH is set. On the other hand, the logic device performs format conversion of the data received in this reception process, transmission to the host computer, and the like. The wireless modem R2 thereafter sets the communication channel to the control channel C-CH and sets the standby state.

After the communication is terminated, the zone tracking processing described above is activated at a cycle of m seconds by timer management in the lower route control.

In this embodiment, the number of terminals on the moving side is one, but when there are a plurality of terminals, the same control as above may be performed for each.

〔The invention's effect〕

According to the present invention, the transmission side selects a communication channel that is vacant by the carrier sense method from a plurality of channels, and performs a call origination by designating the selected communication channel via the control channel. Since the caller receives the call origination via the control channel and responds through the communication channel designated by the call, the carrier sense type channel designation communication is adopted, so that the receiver side receives the call origination from the sender side. Then, the communication channel is immediately set.

Therefore, at the time of transmission from the first terminal to the second terminal, the plurality of first wireless devices sequentially perform the above-mentioned call origination through the control channel, and the second wireless device is waiting for reception on the control channel. As soon as the second wireless device receives a call origination for the first time, communication is set up between the second wireless device and the first wireless device that originated the call origination received by it. In this way, which of the plurality of first wireless devices is set for communication is automatically determined. Therefore, in the first terminal, the process after the call for selecting one of the plurality of first wireless devices is performed. Is not required at all, and there is substantially no delay time from the reception of the call origination by the second wireless device to the connection of the communication line.

In addition, since the communication channel is selected from a plurality of channels by the carrier sense method, the adaptability or flexibility to the number and arrangement of the first wireless devices, the change or extension of the movement route of the second wireless device, the change of the used frequency, or the like. The cost of equipment changes required for changes or expansion is low.

[Brief description of drawings]

FIG. 1 is a plan view showing the configuration of an overhead crane control system for carrying out the present invention as an example, FIG. 2 is a block diagram showing its hardware configuration, and FIG. 3 is a block diagram showing its software configuration. 4a, 4b and 4c are flowcharts showing control in data transmission. FIG. 5 is an explanatory diagram for explaining communication by the hybrid ARQ method performed in the wireless section. 1: Factory building, 2: Overhead crane 10: Ground control terminal (first terminal) 11, 21: Microprocessor 11: (Control means), 12, 22: Main memory 13,23: Timer & counter module 14-17, 24: I / O interface circuit 20: Onboard control terminal (second terminal) R1, R2, R3, C1: wireless modem R1, R2, R3: (first wireless device) C1: (second wireless device) M0, M1a, M1b, M3a, M3b: Wired modem KB1, KB2: Keyboard terminal PTR: Printer, HD1: Hard disk FD1, FD2: Floppy disk

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical indication location 7605-5K H04B 7/26 107 7605-5K H04Q 7/04 K 7605-5K C

Claims (7)

[Claims] 1. Communication between a fixed first terminal and a moving second terminal is carried out via a first wireless device connected to the first terminal and a second wireless device connected to the second terminal. In a wireless communication method for setting a service area including a movement range of a second terminal that exceeds a wireless zone of a single first wireless device when securing the plurality of first wireless devices: a first terminal to a first terminal When transmitting to two terminals, a free communication channel is selected from a plurality of channels by a carrier sense method, and a call originating by designating the selected communication channel is performed via the control channel. The second wireless device first makes a call received by the second wireless device by responding over the communication channel specified by the call first received over the control channel. 1 radio A wireless communication method, wherein the device is set as a first wireless device for communication. 2. The transmission from the first terminal to the second terminal is performed by dividing the transmission content into a plurality of pieces by an interaction between the first wireless device and the second wireless device. ) The wireless communication method described in the section. 3. A first wireless device for making a call that is initially received by a second wireless device as a first wireless device for communication, and at least one of the remaining first wireless devices as a standby first wireless device. When the communication between the first wireless device and the second wireless device for communication is interrupted, the first wireless device for standby receiving the signal from the second wireless device at that time. Update setting for communication, claim (2)
The wireless communication method according to the item. 4. A call is made by selecting an available communication channel by a carrier sense method from a plurality of channels when transmitting from the second terminal to the first terminal and designating the selected communication channel via the control channel. To make a call
The second wireless device makes the first wireless device that receives this call the first wireless device for communication and responds via the designated communication channel. The wireless communication method according to claim (1), wherein one first wireless device sets the designated communication channel and sets the first communication device to wait for reception. 5. When the first wireless device for communication stops receiving a signal from the second wireless device, the first wireless device waiting to receive the signal at that time is updated and set for communication.
The wireless communication method according to claim (4). 6. The transmission from the second terminal to the first terminal is performed by dividing the transmission content into a plurality of pieces by an interaction between the second wireless device and the first wireless device. ) The wireless communication method described in the section. 7. When there is no communication between the first terminal and the second terminal, polling is performed between each first wireless device and the second wireless device to identify the wireless zone in which the second wireless device exists. The wireless communication method according to any one of claims (1), (2), (3), (4), (5) or (6) for tracking.