Wireless data communication system, master station used for the wireless data communication system, wireless data communication method, and wireless data communication control program

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Technical field to which the invention belongs]

The present invention relates to a wireless data communication system, a master station used for a wireless data communication system, a wireless data communication method, and a wireless data communication control program, and relates to a channel allocation method used for wireless data communication.

【0002】

[Conventional technology]

As a wireless data communication technology in the mobile field, so-called non-telephone communication using a circuit switching method is known. In this non-telephone communication, channels are assigned to slave stations on a communication-by-communication basis. Then, the slave station to which the channel is assigned occupies and uses the channel until the end of the communication. When this channel allocation is performed, there is usually no change in the allocation state regardless of the presence or absence of transmitted / received data.

【0003】

On the other hand, in the packet method suitable for data communication, on the contrary, in order to have the best effort orientation, allocation is performed every time data is generated. That is, each communication station autonomously determines the actual transmission timing and starts transmission. For example, in the PDC packet method specified in ARIB (association of radio industries and businesses) STD-27F version or later, data is transmitted by performing random access based on the availability of transmission frames on the wireless channel selected by the slave station. At the same time, it implements a random access control (ICMA-PE) method with partial echo that reserves transmission frames for subsequent transmission data.

【0004】

In the ICMA-PE method, the beginning of the data is transmitted in a short burst, and the remaining data portion is assigned a slot to be transmitted on the same channel. In the case of a communication environment in which the amount of processing and the amount of delay are large, the above-mentioned allocation operation has a non-negligible effect on throughput. As a wireless data communication technology according to such a communication environment, the network allocates channels exclusively to slave stations like circuit switching, but even in the communication state, there is no data to communicate for a certain period of time. After that, the allocation status is released and used for communication of other slave stations, and when data to be communicated again occurs in the slave station, a pseudo-circuit-switched wireless communication method that receives channel allocation from the network again is used. It has been proposed and put into practical use in Japanese Patent Application Laid-Open No. 2000-13852. In simulated circuit switching, an allocation request signal is transmitted, and data is transmitted by allocating a data transmission channel by the network. If the next data occurs before the channel hold timer times out, the same allocated channel can continue to send data.

【0005】

[Problems to be Solved by the Invention]

In circuit switching, lines are continuously allocated until the end of communication, and in circuit switching, channels are continuously allocated if the next transmission data occurs within a certain period of time, and there is no decrease in throughput in the allocated state, but allocation. Since the communication line inside is used exclusively, it cannot be shared with other communications. Therefore, even in simulated circuit switching, in a high load state where all communication lines are allocated, it becomes difficult to accept new communication requests, and the frequency of allocation requests varies depending on the traffic characteristics of the communication information source. There is a drawback that communication lines cannot be used fairly between slave stations.

【0006】

The present invention has been made to solve the above-mentioned drawbacks of the prior art, and an object thereof is a wireless data communication system in which communication lines can be used fairly between each slave station, and a parent used in a wireless data communication system. To provide stations, wireless data communication methods, and wireless data communication control programs.

【0007】

[Means for solving problems]

The wireless data communication system according to claim 1 of the present invention has a plurality of communication radio channels provided between a plurality of slave stations and a master station, wherein the master station allocates the plurality of communication channels according to a predetermined communication channel allocation method. A wireless data communication system that allocates at least one of the communication wireless channels of the above to each of the plurality of slave stations for communication, and measures the utilization rate of the assigned communication radio channels, and the above-mentioned utilization rate measuring means. It is characterized by including a communication channel allocation control means that changes the communication channel allocation method according to the utilization rate measured by the utilization rate measuring means.

【0008】

In the wireless data communication system according to the second aspect of the present invention, in the first aspect, the communication channel allocation control means divides one communication wireless channel into a plurality of communication subchannels according to the measured utilization rate. It is characterized in that the communication channel allocation method is changed so as to allocate to a slave station in units of the divided communication subchannels.

【0009】

In the wireless data communication system according to the third aspect of the present invention, in the second aspect, the communication channel allocation control means uses at least a part of the communication wireless channel during communication using the allocated communication wireless channel. It is characterized in that it is divided into a plurality of communication sub-channels, and the channel allocation for the slave station during the communication is changed for each communication sub-channel.

【0010】

In claim 1, the wireless data communication system according to claim 4 of the present invention also measures the duration of the state in which there is no data to be transmitted in the utilization rate measuring means, and the communication channel in the communication channel allocation control means. The allocation method is characterized in that the duration is included as a condition for releasing the allocation of the communication radio channel.

【0011】

The wireless data communication system according to claim 5 of the present invention is characterized in that, in claim 4, the communication channel allocation control means has different values of the duration before and after the change of the communication channel allocation method. To do. The wireless data communication system according to claim 6 of the present invention is characterized in that, in claim 1, the communication channel allocation control means cancels the use of at least a part of the communication wireless channel during communication.

【0012】

In the wireless data communication system according to claim 7 of the present invention, in claim 6, when the communication channel allocation control means cancels the use of the communication wireless channel during communication, the communication wireless channel is allocated. It is characterized in that the minimum pause time from cancellation to restart is specified. The master station in the wireless data communication system according to claim 8 of the present invention is the plurality of communication radios for a plurality of communication radio channels provided between the plurality of slave stations according to a predetermined communication channel allocation method. A master station in a wireless data communication system in which at least one of the channels is assigned to each of the plurality of slave stations for communication, and a utilization rate measuring means for measuring the utilization rate of the assigned communication wireless channel, and the above-mentioned utilization It is characterized by including a communication channel allocation control means that changes the communication channel allocation method according to the utilization rate measured by the rate measuring means.

【0013】

The master station in the wireless data communication system according to claim 9 of the present invention is the communication channel allocation control means according to claim 8, wherein one communication radio channel is used as a plurality of communication subchannels according to the measured utilization rate. It is characterized in that the communication channel allocation method is changed so as to divide the data into slave stations and allocate the divided communication sub-channels to slave stations.

【0014】

The master station in the wireless data communication system according to claim 10 of the present invention is the communication channel allocation control means according to claim 9, at least of the communication radio channel during communication using the allocated communication radio channel. A part thereof is divided into a plurality of communication sub-channels, and the channel allocation for the slave station during the communication is changed for each communication sub-channel.

【0015】

In claim 8, the master station in the wireless data communication system according to claim 11 of the present invention also measures the duration of the state in which there is no data to be transmitted in the utilization rate measuring means, and the communication channel allocation control means. The communication channel allocation method in the above is characterized in that the duration is included as a condition for releasing the allocation of the communication radio channel.

【0016】

In claim 11, the master station in the wireless data communication system according to claim 12 of the present invention has the communication channel allocation control means having different values of the duration before and after the change of the communication channel allocation method. It is characterized by. The master station in the wireless data communication system according to claim 13 of the present invention is characterized in that, in claim 8, the communication channel allocation control means cancels the use of at least a part of the communication wireless channel during communication. ..

【0017】

The master station in the wireless data communication system according to claim 14 of the present invention is the communication channel allocation control means according to claim 13, when the communication channel allocation control means cancels the use of the communication wireless channel during communication. It is characterized by specifying the minimum pause time from when the allocation of is released to when it is restarted. In the wireless data communication method according to claim 15 of the present invention, with respect to a plurality of communication radio channels provided between a plurality of slave stations and a master station, the master station may allocate the plurality of communication channels according to a predetermined communication channel allocation method. A wireless data communication method in which at least one of the communication wireless channels of the above is assigned to each of the plurality of slave stations for communication, the utilization rate measurement step of measuring the utilization rate of the assigned communication radio channels, and the above-mentioned. It is characterized by including a communication channel allocation control step for changing the communication channel allocation method according to the utilization rate measured by the utilization rate measuring means.

【0018】

In claim 15, the wireless data communication method according to claim 16 of the present invention divides one communication wireless channel into a plurality of communication subchannels according to the measured utilization rate in the communication channel allocation control step. However, the communication channel allocation method is changed so as to allocate to the slave station in units of the divided communication subchannels.

【0019】

The wireless data communication method according to claim 17 of the present invention is the method of claim 16, wherein in the communication channel allocation control step, at least a part of the communication radio channel is used during communication using the allocated communication radio channel. Is divided into a plurality of communication sub-channels, and the channel allocation for the slave station during the communication is changed for each communication sub-channel.

【0020】

In claim 15, the wireless data communication method according to claim 18 of the present invention also measures the duration of the state in which there is no data to be transmitted in the utilization rate measurement step, and the communication channel in the communication channel allocation control step. The allocation method is characterized in that the duration is included as a condition for releasing the allocation of the communication radio channel.

【0021】

The wireless data communication method according to claim 19 of the present invention is characterized in that, in claim 18, in the communication channel allocation control step, the value of the duration is set to a different value before and after the change of the communication channel allocation method. And. The wireless data communication method according to claim 20 of the present invention is characterized in that, in claim 15, at least a part of the communication wireless channel during communication is canceled in the communication channel allocation control step.

【0022】

In claim 20, the wireless data communication method according to claim 21 of the present invention allocates the communication wireless channel in the communication channel allocation control step when the use of the communication wireless channel during communication is canceled. It is characterized by specifying the minimum pause time from the release of to the restart. In the wireless data communication control program according to claim 22 of the present invention, with respect to a plurality of communication radio channels provided between a plurality of slave stations and a master station, the master station may use a predetermined communication channel allocation method. A wireless data communication control program for allocating at least one of a plurality of communication wireless channels to each of the plurality of slave stations for communication, and measuring the utilization rate of the assigned communication wireless channels. It is characterized by including a step and a communication channel allocation control step for changing the communication channel allocation method according to the utilization rate measured by the utilization rate measuring means.

【0023】

In claim 22, the radio data communication control program according to claim 23 of the present invention converts one communication radio channel into a plurality of communication subchannels according to the measured utilization rate in the communication channel allocation control step. It is characterized in that the communication channel allocation method is changed so as to divide the data and allocate the divided communication sub-channels to slave stations.

【0024】

The wireless data communication control program according to claim 24 of the present invention has, in claim 23, in the communication channel allocation control step, at least one of the communication radio channels during communication using the allocated communication radio channel. The unit is divided into a plurality of communication sub-channels, and the channel allocation for the slave station during communication is changed for each communication sub-channel.

【0025】

In claim 22, the wireless data communication control program according to claim 25 of the present invention also measures the duration of the state in which there is no data to be transmitted in the utilization rate measurement step, and communicates in the communication channel allocation control step. The channel allocation method is characterized in that the duration is included as a condition for releasing the allocation of the communication radio channel.

【0026】

In the wireless data communication control program according to claim 26 of the present invention, in claim 25, in the communication channel allocation control step, the value of the duration is set to a different value before and after the change of the communication channel allocation method. It is a feature. The radio data communication control program according to claim 27 of the present invention is characterized in that, in claim 22, at least a part of the communication radio channel during communication is canceled in the communication channel allocation control step.

【0027】

In claim 27, the wireless data communication control program according to claim 28 of the present invention uses the communication wireless channel when the use of the communication wireless channel during communication is canceled in the communication channel allocation control step. It is characterized by specifying the minimum pause time from the release of the allocation to the restart. In short, this system handles multiple channels collectively, allocates communication lines appropriately to these combined multiple channels, and changes the channel allocation method even during communication, so a high load close to the resource upper limit. Communication opportunities can be made fair in such a situation.

【0028】

BEST MODE FOR CARRYING OUT THE INVENTION

Next, an embodiment of the present invention will be described with reference to the drawings. In each figure referred to in the following description, the same parts as those in the other figures are indicated by the same reference numerals. FIG. 1 is a block diagram showing a configuration of an embodiment of a wireless data communication system according to the present invention. As shown in the figure, in the wireless data communication system according to the present embodiment, the master station 4 that transmits data and the slave stations 1-1 to 1-2 that receive the data transmitted from the master station 4 It is composed including and. The master station 4 is also connected to the data communication network 5, and the data received from the data communication network 5 can be transmitted to the slave stations 1-1 to 1-2.

【0029】

The slave stations 1-1 to 1-2 perform data communication with the master station 4 connected to the data communication network 5 via the communication lines 3-1 to 3-N. The communication lines 3-1 to 3-N are selected based on the control information exchanged between the slave station 1 and the master station 4 via the control line 2. An example of the internal configuration of the master station 4 in FIG. 1 is shown in FIG. As shown in the figure, the master station 4 allocates a communication channel to a utilization rate measuring unit 41 that measures the channel utilization rate and a communication channel according to the utilization rate measured by the utilization rate measuring unit 41. It includes a channel allocation control unit 42 and a data transmission / reception unit 43 that transmits / receives data to / from a slave station using the channel allocated by the communication channel allocation control unit 42.

【0030】

The utilization rate measuring unit 41 refers to the communication lines 3-1 to 3-N and counts the number of line allocations, the allocation time for each session, the cumulative allocation time for each call, the number of frames actually transmitted / received per allocation, and the like. By doing so, the utilization rate of the channel is measured. The communication channel allocation control unit 42 allocates channels and changes the allocation method. Changing the allocation method means changing the allocation rule according to the amount of free resources. For example, actions such as changing the number of communication calls for channel sharing, dynamically changing the clock value of the channel hold timer, forcibly releasing the allocated channel by the master station, and issuing a restart instruction correspond to the change in the allocation method. To do.

【0031】

Further, the communication channel allocation control unit 42 refers to the utilization rate measured by the utilization rate measurement unit 41, and when the number of allocated lines approaches the upper limit, the communication channel allocation control unit 42 sets the control target based on the allocation time and the number of transmission / reception frames. Select a channel. Further, the communication channel allocation control unit 42 may define subchannels for the entire provision channel regardless of the allocation state. A subchannel refers to a dynamically divided channel, which is a code in CDMA (code division multiple access), the number of allocated slots in TDMA (time division multiple access), polarization division in OFDM (orthogonal frequency division multiplexing), and FDMA (frequency). Subcarriers due to band division in division multiple access) correspond to subchannels.

【0032】

The channel allocation referred to here is a resource allocation for one transmission data unit. In other words, it has a different meaning from continuous allocation for logical communication (whether or not data is actually sent or received) such as circuit switching. In this system, resource allocation is not controlled within one channel, but the entire provision channel is regarded as a resource and controlled.

【0033】

When the utilization rate of one channel is controlled, there is a possibility that a call that receives an unfavorable channel allocation may occur even though there is a capacity margin in the other channel. On the other hand, by controlling the utilization rate of the entire plurality of channels as in this system, it is possible to fairly provide communication opportunities in a high load state close to the resource upper limit.

【0034】

The data transmission / reception unit 43 has a function of selecting communication lines 3-1 to 3-N based on the control information exchanged between the slave station 1 and the master station 4 via the control line 2. .. An example of the internal configuration of the slave station in Fig. 1 is shown in Fig. 3. As shown in the figure, the slave station measures the duration of the non-transmission state with the data transmission / reception unit 11 that transmits / receives data to / from the master station using the channel assigned by the master station. It is configured to include a channel hold timer 12 to be used. Instead of the channel hold timer 12, a line hold timer that measures the line usage time and a transmission break timer that measures the break time of the transmission state may be adopted.

【0035】

Note that this system can be adopted even in the configuration in which the downlink direction is a common access channel and the communication line is selected only in the uplink direction in FIG. 1. In addition, this system can be adopted even in a configuration via a communication satellite between the master station 4 and the slave station 1. Further, the slave station and the master station may be a mobile station and a base station, or may be a fixed terminal and a home antenna, and this system can be adopted in any case.

【0036】

In the wireless data communication system having the configurations shown in FIGS. 1 to 3, the utilization rate measuring unit 41 in the master station 4 measures the channel utilization rate. Then, the communication channel allocation control unit 42 allocates the communication channel according to the measured utilization rate. Data is transmitted and received between the master station and the slave station by using the channel assigned by the communication channel allocation control unit 42.

【0037】

When allocating communication channels, this system handles multiple channels collectively. Furthermore, in this system, the channel allocation method is changed even during communication. After changing the allocation method, one communication radio channel is divided into a plurality of communication subchannels and allocated in units of communication subchannels, or all or part (that is, at least one subchannel) is in communication. The communication radio channel is divided into a plurality of communication sub-channels, and the method of allocating slave stations during communication using the communication radio channel is also changed for each communication sub-channel.

【0038】

As a condition to cancel the use of the communication wireless channel in this system, the duration of the state where there is no data to be transmitted is used as a part of the channel allocation method, and there is no data to be transmitted before and after the channel allocation method is changed. Change the duration of the state or deactivate the communication radio channel of all or some of the slave stations during communication. Alternatively, after changing the allocation method that specifies the minimum pause time until the request for allocating the communication wireless channel is resumed, one communication wireless channel is divided into multiple communication subchannels and allocated in units of communication subchannels. Or, the communication radio channel during communication in whole or part is divided into a plurality of communication sub-channels, and the method of allocating the slave stations in communication using the communication radio channel is also changed for each communication sub-channel. To do.

【0039】

Further, as a condition for canceling the use of the communication wireless channel, the duration of the state where there is no data to be transmitted is used as a part of the channel allocation method, and there is no data to be transmitted before and after the change of the allocation method. Specify a minimum pause time until the duration of is set to a different value, the use of all or some of the slave stations during communication is canceled, or the request for allocation of the communication radio channel is resumed. To do.

【0040】

Since the control is performed as described above, in this system, communication opportunities can be made fair in a high load state close to the upper limit of resources.

【0041】

[Example]

Next, the radio channel selection control procedure in this system will be described. FIG. 4 shows an example in a wireless data communication system in which a master station allocates a communication line based on a request of a slave station, in which a subchannel is defined for a communication line that can be assigned by the master station and assigned to the slave station. ing.

【0042】

In this embodiment, the master station 4 monitors the number of communication lines 3 that can be assigned as the usage status of the communication line 3, and the allocation request signal 6-1 from the slave station 1-1 is in a situation where the number falls below a certain number. Is received, a plurality of subchannels are defined for the assignable channel, and the allocation response signal 7-1 in which the subchannel is specified is transmitted to the slave station 1-1. Data is transmitted and received between the master station 4 and the slave station 1-1 using the subchannel specified by the assigned response signal 7-1.

【0043】

Here, the definition of a subchannel means an operation of sharing a resource that has been or is scheduled to be allocated to a certain communication partner with another communication partner. For example, in FDMA, when one channel is assigned to one communication partner, it refers to an operation of changing so that transmission / reception rights are assigned between odd-numbered frames and even-numbered frames.

【0044】

If data is transmitted / received via the subchannel as described above and the allocation request signal 6-2 is further transmitted from the slave station 1-2, the master station 4 allocates the unallocated subchannel and the child The allocation response signal 7-2 with the subchannel specified is transmitted to station 1-1. Then, data is transmitted / received between the master station 4 and the slave station 1-2 using the subchannel specified by the allocation response signal 7-2.

【0045】

In this embodiment, by defining a subchannel, a communication line is shared by a plurality of slave stations, and a large number of communications can be performed using limited radio resources. FIG. 5 shows an example in which a subchannel is also defined for the communication line being assigned, and the allocation method is changed to the slave station being communicated to specify the subchannel. In the figure, the slave station 1-1 transmits the allocation request signal 8-1 on the control line 2, and the communication line 3-1 is assigned to the slave station 1-1 by the allocation response signal 9-1 from the master station 4. .. Data is transmitted and received between the master station 4 and the slave station 1-1 using this assigned communication line 3-1.

【0046】

When the slave station 1-2 further transmits the allocation request signal 8-2 on the control line 2 in this transmission / reception state, a certain number of channels can be allocated as the utilization rate monitored by the master station 4. When interrupting, for example, a subchannel is defined for the assigned channel with the lowest channel usage rate, and this subchannel is assigned to the slave station 1-1 that is already communicating and the new slave station 1-2. The definition of the sub-channel for wireless channel sharing can be realized in, for example, TDMA or CDMA.

【0047】

When the master station 4 transmits the allocation status change signal 10-1 to the preliminary station 1-1 and receives the reply of the allocation status change confirmation signal 11-1, the allocation response signal is sent to the slave station 1-2. Send 9-2 to notify the subchannel allocation. After the transmission of the assigned response signal 9-2, data is transmitted / received between the master station 4 and the slave stations 1-1 and 1-2. The selection of the communication line under allocation that defines the sub-channel is based on the channel usage rate as described above, the method of selecting the wireless channel with the longest allocation time, the setting of a flag inside the allocation request signal, etc. It is also possible to use the method based on the prior application by the slave station of.

【0048】

Even though the sub-channel is assigned, there may be a time when data is not actually transmitted or received. For example, the time waiting for the generation of data to be transmitted. Such time reduces channel utilization. Therefore, in this system, the slave station measures the duration of the non-transmission state by using the channel hold timer 12. Then, when the channel hold timer 12 times out, the release signal 13 for releasing the communication line 3 is transmitted from the slave station 1-1.

【0049】

Here, the channel hold timer is a timer that measures the time limit for securing (holding) the allocated channel. A sender who has been assigned a channel can continue to transmit using that channel as long as the transmission data exists, and even if there is no data to transmit, the channel will continue to be transmitted until the timed by the channel hold timer expires. The usage right (transmission / reception right) can be maintained. When the channel hold timer times out, the channel allocation is autonomously released. If new data to be transmitted occurs before the timeout, the timekeeping operation by the channel hold timer will be started again.

【0050】

When the release signal 13 is transmitted from the slave station 1-1, the master station 4 cancels the subchannel definition of the communication line 3 based on the measured utilization rate and allows the slave station 1-2 to exclusively use it. Decide whether to maintain. When canceling the sub-channel, the allocation status change signal 10-2 is transmitted to the slave station 1-2 to instruct. Even when the number of slave stations to be multiplexed is larger than the two stations shown in the figure, such a channel allocation change can be easily realized.

【0051】

In this embodiment, by appropriately designating the sub-channel, the communication line can be shared by a plurality of slave stations to increase the usage rate of the communication line and enable a large number of communications with limited wireless resources. For example, when a communication call to be shared with a channel having a large amount of transmission is a small amount transmission, the subchannel is appropriately notified by notifying the master station side of the amount of transmission data in advance when requesting allocation. You can specify and increase the usage rate of the communication line. In addition, in order to collect discrete communication calls and share one channel, if the traffic characteristics of each communication unit are monitored and fed back, the sub-channel can be specified appropriately and the usage rate of the communication line can be increased. it can.

【0052】

FIG. 6 shows an embodiment in which the duration in which there is no data to be transmitted is used as part of the allocation condition of the communication line, and the master station changes the duration as a means of changing the allocation method and notifies the slave station. It is shown. As shown in the figure, when slave station 1-1 receives the allocation of communication line 3 from master station 4 and sends / receives data, the line hold that starts based on the preset duration. If no new communication data is generated in the slave station 1-1 until the timer 14-1 times out, the communication line 3 is released. The master station 4 monitors the remaining number of communication lines 3 that can be assigned as the utilization rate of the communication line 3, and changes the setting value of the line hold timer when the threshold value is exceeded. Specifically, the set time value of the line hold timer is changed to a shorter time value.

【0053】

The slave station 1-1 during communication is notified of the change by transmitting the allocation status change signal 15 from the master station 4, and the slave station 1-1 returns the allocation status change confirmation signal 16. By doing so, the subsequent line hold timer 14-2 operates at the new set value time value. The target for the master station 4 to change the line hold timer 14 is a control in which the master station 4 monitors traffic characteristics such as a data transmission interval for each communication session and changes the line hold timer accordingly. In addition, a method of shortening the time value of the line hold timer for communication that uses the same communication line continuously for a certain period of time or longer, or changing the time value of the line hold timer to "0" immediately It is also conceivable to control the release of the allocation for each communication line.

【0054】

In this embodiment, even after the communication line is once allocated, the frequency of releasing the allocated line can be affected by changing the clock value of the line hold timer. That is, if the clock value of the line hold timer is shortened, the possibility of releasing the allocated line increases, so that the free frequency of the communication line 3 increases. Further, if the master station selects the timing time length of the hold timer that matches the burst property of the communication data, the number of activations of the allocation procedure can be reduced, the overhead associated with the allocation procedure can be suppressed, and the traffic of the control line can be reduced.

【0055】

FIG. 7 shows an example in which the master station cancels the allocation state of the communication line to the slave station in communication. In this example, as in the case of FIG. 5, the master station 4 controls the communication line 3 based on the utilization rate. In the figure, the slave station 1-1 transmits the allocation request signal 20-1 on the control line 2, the master station 4 returns the allocation response signal 21-1, and the communication line 3-1 is the slave station 1-1. Assigned to. Data is transmitted and received between the master station 4 and the slave station 1-1 using this assigned communication line.

【0056】

When the slave station 1-2 transmits the allocation request signal 20-2 on the control line 2 while this data is being transmitted / received, the master station 4 is the slave station 1- while using the communication line 3-1. The allocation status change signal 22 for canceling the allocation status is transmitted to 1. The slave station 1-1 returns the allocation status change confirmation signal 23 and interrupts the transmission. After receiving the allocation status change confirmation signal 23, the master station 4 transmits an allocation response signal 21-2 that allocates the communication line 3-1 to the slave station 1-2. Communication line 3-1 is assigned to slave station 1-1 by this allocation response signal 21-2. Data is transmitted and received between the master station 4 and the slave station 1-2 using this assigned communication line 3-1.

【0057】

On the other hand, the slave station 1-1 autonomously expires the interruption state when the predetermined transmission interruption timer 24 times out. If there is data to be transmitted in the slave station 1-1, the allocation request signal 20-3 is transmitted to the master station 4 again to receive the allocation of an appropriate line among the communication lines 4. As another method for autonomously expiring the interruption of transmission, it is easy to realize a method in which the master station 4 notifies the free status of the communication line 3 on the control line 2 and restarts the transmission when there is a free space. it can.

【0058】

In this embodiment, it is possible to control the communication that occupies the line for a long time by canceling the selection from the master station side for the communication for which the wireless channel is once selected. In addition, by interrupting transmission of the released slave station, other communication can proceed during that time, and since the slave station autonomously decides to resume transmission, communication can be continued according to the communication status of the slave station. Will be.

【0059】

FIG. 8 shows an example in which the selected state is canceled from the master station side and the difficult station notifies the slave station of the restart. In this example, as in the case of FIG. 5, the slave station 1-1 transmits the allocation request signal 25-1 on the control line 2, the master station 4 returns the allocation response signal 26-1, and the communication line 3 -1 is assigned to slave station 1-1. Data is transmitted and received between the master station 4 and the slave station 1-1 using this assigned communication line.

【0060】

In the state where this data is being transmitted / received, if the master station 4 selects the communication line 3 due to the new allocation request 25-2 of the slave station 1-2, the master station 4 sends the slave station 1-1 to the slave station 1-1. The allocation status change signal 27 for stopping the transmission is transmitted. The slave station 1-1 returns the allocation status change confirmation signal 28 and interrupts the data transmission. As a result, data transmission is stopped between the master station 4 and the slave station 1-1.

【0061】

After receiving the allocation status change confirmation signal 28, the master station 4 transmits an allocation response signal 26-2 that allocates the communication line 3 to the slave station 1-2. As a result, data transmission / reception is continued between the master station 4 and the slave station 1-2 with the channel allocation changed. After that, the master station 4 recovers the allocation status of the slave station 1-1 based on the communication status of the slave station 1-2 or the condition that another communication line 3 has a vacancy. When recovering the allocation state, the master station 4 transmits a reassignment signal 29 to the slave station 1-1. As a result, an appropriate communication line is selected, and data is transmitted / received between the master station 4 and the slave station 1-1.

【0062】

In this embodiment, as in the case of the embodiment of FIG. 7, in addition to the control for the communication that occupies the same communication line 3 for a long period of time, the allocation control is performed under the initiative of the master station, so that all the communication lines 3 are used. It is also possible to operate under the high load condition. In each of the above embodiments, the following wireless data communication methods are realized. That is, with respect to the plurality of communication radio channels provided between the plurality of slave stations and the master station, the master station may use at least one of the plurality of communication radio channels according to a predetermined communication channel allocation method. It is a wireless data communication method that assigns and communicates to each of a plurality of slave stations, and according to the utilization rate measurement step for measuring the utilization rate of the assigned communication wireless channel and the utilization rate measured by the above utilization rate measuring means. A wireless data communication method including a communication channel allocation control step for changing the communication channel allocation method has been realized. Then, in the communication channel allocation control step, one communication radio channel is divided into a plurality of communication subchannels according to the measured utilization rate, and the divided communication subchannels are assigned to the slave stations. The above communication channel allocation method has been changed. Further, in the communication channel allocation control step, during communication using the allocated communication radio channel, at least a part of the communication radio channel is divided into a plurality of communication subchannels, and the child during the communication. The channel allocation for stations is changed for each of the above communication subchannels.

【0063】

In the utilization rate measurement step, the duration in the state where there is no data to be transmitted is also measured, and in the communication channel allocation method in the communication channel allocation control step, the duration is assigned to the communication radio channel. Is included as a condition to cancel. Further, in the communication channel allocation control step, the value of the duration is set to a different value before and after the change of the communication channel allocation method. Then, in the communication channel allocation control step, the use of at least a part of the communication radio channel during communication is canceled. In the communication channel allocation control step, when canceling the use of the communication radio channel during communication, the minimum pause time from canceling the allocation of the communication radio channel to restarting is specified.

【0064】

If a program for realizing the operations shown in FIGS. 4 to 8 is prepared and each part of FIGS. 1 to 3 is controlled by using the program, the same channel allocation control as described above can be performed. It is clear that you can. As shown in FIG. 9, in this program, with respect to a plurality of communication radio channels provided between a plurality of slave stations and a master station, the master station may use a predetermined communication channel allocation method. A wireless data communication control program that allocates at least one of a plurality of communication wireless channels to each of the plurality of slave stations for communication, and measures the utilization rate of the assigned communication wireless channels. Utilization rate measurement step S91. And the communication channel allocation control step S92 that changes the communication channel allocation method according to the utilization rate measured by the utilization rate measuring means. Then, in the communication channel allocation control step S92, one communication radio channel is divided into a plurality of communication subchannels according to the measured utilization rate, and the divided communication subchannels are assigned to the slave stations. The above communication channel allocation method is changed as described above. Further, in the communication channel allocation control step S92, during communication using the allocated communication radio channel, at least a part of the communication radio channel is divided into a plurality of communication subchannels, and the communication is in progress. The channel allocation for the slave station is changed for each of the above communication subchannels.

【0065】

In the utilization rate measurement step S91, the duration in the state where there is no data to be transmitted is also measured, and the communication channel allocation method in the communication channel allocation control step S92 uses the duration as the communication radio channel. Included as a condition to release the allocation of. Further, in the communication channel allocation control step S92, the value of the duration is set to a different value before and after the change of the communication channel allocation method. Then, in the communication channel allocation control step S92, the use of at least a part of the communication radio channels during communication is canceled. In the communication channel allocation control step S92, when canceling the use of the communication radio channel during communication, the minimum pause time from canceling the allocation of the communication radio channel to restarting is specified.

【0066】

As the recording medium for recording the above program, various recording media can be used in addition to semiconductor memories, magnetic disks, optical disks, etc., which are not shown in FIGS. 1 to 3. With respect to the description of the claims, the present invention may further adopt the following aspects. (1) A plurality of communication radio channels are provided between a plurality of slave stations and a master station, and the master station assigns one of the communication radio channels to the slave station in response to a request from the slave station. In a wireless data communication system that communicates, the master station is provided with a function of measuring the utilization rate of the communication wireless channel, and when the utilization rate of the communication wireless channel exceeds a predetermined threshold, the slave station is reached. A wireless data communication system characterized by changing the communication channel allocation method of.

【0067】

(2) The wireless data communication system according to (1), wherein after changing the allocation method, one communication wireless channel is divided into a plurality of communication subchannels and allocated in units of communication subchannels. (3) After changing the allocation method, the communication radio channel during communication is divided into a plurality of communication sub-channels, and the slave station during communication is allocated using the communication radio channel. The wireless data communication system according to (2), which is characterized in that it is also changed in units of communication subchannels.

【0068】

(4) As a condition for canceling the use of the communication wireless channel, the duration in which there is no data to be transmitted is used as a part of the allocation method, and the data to be transmitted before and after the change of the allocation method. The wireless data communication system according to (1), wherein the duration of the state is changed. (5) A plurality of communication radio channels are provided between a plurality of slave stations and a master station, and the master station assigns one of the communication radio channels to the slave station in response to a request from the slave station. In a wireless data communication system that performs communication, the master station is provided with a function of measuring the utilization rate of the communication wireless channel, and when the utilization rate of the communication wireless channel exceeds a predetermined threshold value, communication is in progress. A wireless data communication system characterized in that the use of communication radio channels of all or some of the slave stations is canceled.

【0069】

(6) When canceling the use of the communication radio channel of all or a part of the slave stations during the communication, the minimum pause time until the request for allocating the communication radio channel is restarted is specified. (5) The wireless data communication system described.

【0070】

[Effect of the invention]

As described above, according to the present invention, the master station allocates one of the communication radio channels between the plurality of slave stations and the master station via a plurality of communication radio channels according to the request of the slave station. By changing the wireless channel allocation method by the master station, it is possible to improve the channel usage rate and realize effective use. Then, as a channel allocation method, if a subchannel is defined and used as an allocation unit, there is an effect that the communication radio channel can be shared. In addition, there is an effect that control for a slave station in which the allocation state of the same channel continues for a long time and control for avoiding a state where the communication channel is scarce can be realized by an instruction to change the channel hold timer or an instruction to release the allocation.

[Simple explanation of drawings]

[Figure 1]

It is a block diagram which shows the system structure of one Embodiment of the wireless data communication system by this invention.

[Figure 2]

It is a block diagram which shows the configuration example of the master station in the wireless data communication system of FIG.

[Fig. 3]

It is a block diagram which shows the configuration example of the slave station in the wireless data communication system of FIG.

[Fig. 4]

It is a figure which shows the communication sequence in 1st Example of the wireless data communication system by this invention.

[Fig. 5]

It is a figure which shows the communication sequence in the 2nd Example of the wireless data communication system by this invention.

[Fig. 6]

It is a figure which shows the communication sequence in the 3rd Example of the wireless data communication system by this invention.

[Fig. 7]

It is a figure which shows the communication sequence in 4th Example of the wireless data communication system by this invention.

[Fig. 8]

It is a figure which shows the communication sequence in 5th Example of the wireless data communication system by this invention.

[Fig. 9]

It is a flowchart which shows the content of the wireless data communication control program by this invention.

[Explanation of symbols]

1-1,1-2 Slave station 2 control line 3-1 ~ 3-N communication line 4 master station 11,43 Data transmitter / receiver 12 channel hold timer 41 Utilization measurement unit 42 Communication channel allocation control unit