JP7013721B2 - Wireless communication devices, wireless communication programs, and wireless communication systems - Google Patents

Description

The present invention relates to a wireless communication device, a wireless communication program, and a wireless communication system, and can be applied to, for example, a wireless network that employs a time division multiple access method and a channel hopping method.

Conventionally, there is a wireless communication system that avoids frame collision by adopting a time division multiple access system and giving transmission rights only to wireless communication devices assigned to time slots.

Further, if frame transmission / reception is performed only on a certain channel, the transmission error rate of the wireless communication device may increase due to radio wave interference. Therefore, there is also a wireless channel hopping method in which the transmission channel is changed for each frame and a channel in which radio wave interference is unlikely to occur is also used to suppress the total transmission error rate.

As a method having both functions of such a time division multiple access method and a channel hopping method, there are Bluetooth (registered trademark), TSCH (Time Slotted channel hopping) (see, for example, Non-Patent Document 1) and the like.

In TSCH, there are an occupied time slot and a shared time slot (broadcast time slot). A wireless link (between the source / destination wireless communication device) is fixedly assigned to the occupied time slot, and wireless communication devices other than these do not need to wait for reception. The shared slot shares the time slot with all wireless communication devices. If there is no transmission frame, the frame is not transmitted from another wireless communication device or is in a reception waiting state. Then, the wireless communication device transmits in the shared time slot when the broadcast frame or the destination address is not assigned to the occupied time slot, and all the surrounding wireless communication devices receive the wireless signal.

There are centralized control and link unit control methods as time slot allocation methods. Centralized control is a method of collecting network topology information and allocating time slots to each wireless communication device. Further, the link unit control is a method in which a time slot used in both wireless communication devices of the link is determined in advance, and a frame is transmitted / received using this time slot.

IEEE Standard for Local and metropolitan area network Part 15.4: Low-Rate Willless Personal Area Networks (LR-WPANs)

However, when a transmission error occurs, the wireless communication device adopting the above-mentioned TSCH method waits until the next time slot having the transmission right. Further, the wireless communication device can reduce the transmission error rate by not using a channel having a high transmission error rate so as to avoid interference as much as possible, but the delay is also large in this case as well. In particular, in data transfer by multi-hop communication, there is a problem that the end-to-end delay increases as the number of hops increases.

Therefore, a wireless communication device, a wireless communication program, and a wireless communication system capable of efficiently performing wireless communication while avoiding radio wave interference while considering the amount of communication delay are desired.

The first aspect of the present invention is a wireless communication device that employs a time-division multiple access method and changes a channel for each time-division time slot. From the storage means for storing information on the number of transmission errors, (2) the transmission error rate derived from the information stored in the storage means when transmitting data to another wireless communication device, and the current time slot position. It has a transmission timing determining means for selecting the time slot for data transmission from the assigned transmittable time slots based on the communication delay time which is the number of time slots until the next transmission right time slot . It is characterized by that.

The second wireless communication program of the present invention employs a time-divided multiple connection method, and a computer mounted on a wireless communication device that changes a channel for each time-divided time slot is (1) at least a data transmission destination. , A storage means for storing information on the number of successful transmissions and the number of transmission errors for each channel used, and (2) a transmission error derived from the information stored in the storage means when transmitting data to another wireless communication device. Based on the communication delay time, which is the number of time slots from the rate and the current time slot position to the time slot to which the next transmission right is granted, the time slot for data transmission from the assigned transmittable time slots is selected. It is characterized in that it functions as a means for determining the transmission timing to be selected.

A third aspect of the present invention is a wireless communication device system in which the first wireless communication device of the present invention is applied as the wireless communication device in a wireless communication device system composed of a plurality of wireless communication devices.

According to the present invention, wireless communication can be efficiently performed while avoiding radio wave interference while considering the amount of communication delay.

It is a block diagram which shows the structure of the wireless communication apparatus which concerns on 1st Embodiment. It is a block diagram which shows the example of the whole structure of the wireless communication system which concerns on 1st Embodiment. It is a figure which shows the configuration example of the neighborhood communication apparatus management table which concerns on 1st Embodiment. It is a flowchart which shows the characteristic operation (the content update of the neighborhood communication apparatus management table) of the wireless communication apparatus which concerns on 1st Embodiment. It is a flowchart which shows the characteristic operation (frame transmission in the occupied slot) of the wireless communication apparatus which concerns on 1st Embodiment. It is a figure which shows the structural example of the transmission right allocation rate table which concerns on 1st Embodiment. It is a figure which shows the example of allocation of the time slot which concerns on 1st Embodiment. It is a figure which shows the example of allocation of the time slot which concerns on 2nd Embodiment. It is a flowchart which shows the characteristic operation (frame transmission in the occupied slot) of the wireless communication apparatus which concerns on 2nd Embodiment. It is a figure which shows the time slot allocation example (multi-hop network) which concerns on 2nd Embodiment.

(A) First Embodiment Hereinafter, the first embodiment of the wireless communication device, the wireless communication program, and the wireless communication system according to the present invention will be described in detail with reference to the drawings.

(A-1) Configuration of First Embodiment (A-1-1) Overall Configuration FIG. 2 is a block diagram showing an example of an overall configuration of a wireless communication system according to the first embodiment.

In the wireless communication system 1, a network management device 5 that manages a network (wireless communication device) and a plurality of wireless communication devices 10 (10-1 to 10-n) that perform wireless communication are arranged. The number of each device arranged in the wireless communication system 1 is not limited, but in the wireless communication system 1 of this embodiment, one network management device 5 and a plurality of wireless communication devices 10 (10-1) are used. It will be described assuming that ~ 10-n) is arranged. Further, the communication method of the network management device 5 and the wireless communication device 10 is not particularly limited, and for example, various wireless LAN interfaces can be applied. In this embodiment, it is premised that the network management device 5 and the wireless communication device 10 perform wireless communication by the wireless communication method of TSCH. Hereinafter, for convenience of explanation, the network management device 5 and the wireless communication device 10 constituting the wireless communication system 1 (wireless network) are collectively referred to as “nodes”.

The network management device 5 manages information about each wireless communication device 10 in the network and notifies the link information to the corresponding wireless communication device 10. The link information is information on which time slot the frame is transmitted or received to the destination (destination address). Further, the network management device 5 has a function of managing channel hopping information of the network and notifying all wireless communication devices 10. The network management device 5 may be configured as software for some configurations. Further, the function of the network management device 5 may be possessed by any one of the plurality of wireless communication devices 10.

(A-1-2) Detailed Configuration of Wireless Communication Device FIG. 1 is a block diagram showing a configuration of a wireless communication device according to the first embodiment. The wireless communication device according to the first embodiment may be configured as hardware such as a dedicated IC chip equipped with each component shown in FIG. 1, or may be mainly composed of a CPU and a program executed by the CPU. Although it may be configured as software, it can be functionally represented by FIG.

In FIG. 1, the wireless communication device 10 includes a transmission / reception control unit 11, a wireless reception unit 12, a reception frame analysis unit 13, a transmission timing determination unit 14, a wireless transmission unit 15, a transmission / reception counter 16, and a proximity communication device management table 17. ..

The transmission / reception control unit 11 notifies an upper layer (not shown) of the contents of the reception frame acquired from the reception frame analysis unit 13 described later. Further, the transmission / reception control unit 11 has a function of instructing the transmission timing determination unit 14 to transmit if there is a transmission request frame.

The wireless receiving unit 12 performs demodulation processing on a wireless signal from an antenna (not shown), converts it into digital data (frames), and gives it to the receiving frame analysis unit 13.

The reception frame analysis unit 13 analyzes the destination address of the input frame from the wireless transmission unit 15 and gives the frame to the transmission / reception control unit 11 if the frame is taken into the own device, and discards the input frame if the destination is other than itself. Further, the reception frame analysis unit 13 has a function of notifying the transmission / reception counter 16 of the reception result.

The transmission timing determination unit 14 is given destination and exclusion channel information together with the transmission frame from the transmission / reception control unit 11, and inputs the transmission frame to the wireless transmission unit 15 when the corresponding time slot and the transmittable channel are reached. Further, the transmission timing determination unit 14 has a memory for holding one or more frames so that the frames that have been put on hold for transmission can be held.

The wireless transmission unit 15 converts a transmission frame (transmission request) given by the transmission timing determination unit 14 into a wireless signal (performs modulation processing) and supplies it to an antenna (not shown).

The transmission / reception counter 16 has a function of recording the transmission / reception result in the neighborhood communication device management table 17. FIG. 3 is a diagram showing a configuration example of the neighborhood communication device management table according to the first embodiment.

In FIG. 3, the neighborhood communication device management table 17 shows the destination addresses of all the wireless communication devices 10 within the range that can communicate with the local wireless communication device 10, and the frame transmission success count, the frame reception success count, and the frame transmission error for each channel. It is a table which records the number of times and the number of times of frame reception error. In the neighborhood communication device management table 17, the number of frame reception errors may be omitted, or other information may be recorded. Further, in FIG. 3 (and FIG. 6 described later), the code of each node (wireless communication device) is shown in the destination address for the sake of simplicity.

The wireless communication device 10 generates a transmission right allocation rate (transmission right allocation rate table TB) for each destination (destination address) and transmission channel as shown in FIG. 6, which will be described later, based on the neighborhood communication device management table 17.

Since the management of the neighborhood communication device management table 17 is performed according to the communication result for each destination using the occupied time slot, the content update processing of the neighborhood communication device management table 17 is not performed for the communication result of the shared time slot. The specific usage of the neighborhood communication device management table 17 and the transmission right allocation rate table TB will be described in the section of operation.

(A-2) Operation of the First Embodiment Next, the operation of the wireless communication system 1 of the first embodiment having the above configuration will be described with reference to the drawings. In this embodiment, the operation of each wireless communication device 10 constituting the wireless communication system 1 has a feature. Therefore, the operation of the wireless communication device 10 will be described below. Although there are some overlapping parts in the process of updating the contents of the neighborhood communication device management table in FIG. 4 and the frame transmission process in the occupied slot in FIG. 5, the overlapping parts will be described again.

(A-2-1) Content update process of the neighborhood communication device management table 17 of the wireless communication device 10. FIG. 4 shows the characteristic operation of the wireless communication device according to the first embodiment (content update of the neighborhood communication device management table). It is a flowchart which shows. When the wireless communication device 10 reaches a time slot in which frames can be transmitted and received, the wireless communication device 10 also starts updating the neighborhood communication device management table 17.

The transmission timing determination unit 14 determines whether or not the current time slot is an occupied time slot (S101). If the current time slot is an occupied time slot, the transmission timing determination unit 14 executes the process of S102 described later, and if not (shared time slot), the transmission timing determination unit 14 ends the update process of the neighborhood communication device management table 17.

The transmission timing determination unit 14 determines whether the time slot (occupied time slot) is a transmission slot or a reception slot (S102). When the time slot is a transmission slot, the transmission timing determination unit 14 processes step S103, which will be described later, and when the time slot is a reception slot, step S107, which will be described later.

The transmission timing determination unit 14 gives a transmission frame from the transmission / reception control unit 11 to the wireless transmission unit 15 in the corresponding slot (transmission slot). Then, the wireless transmission unit 15 wirelessly transmits the input transmission frame (S103).

The reception frame analysis unit 13 determines whether or not the transmission process in step S103 described above was successful (S104). For example, in the case of frame transmission with an ACK (acknowledgement) request, if the reception frame analysis unit 13 determines (analyzes) that the ACK signal from the transmission destination wireless communication device 10 has been received, the transmission is successful. Further, in the case of frame transmission without ACK, the wireless communication device 10 may be regarded as successful transmission if the carrier sense is successful. If the wireless frame transmission is successful, the process of step S105 described later is executed, and if the transmission fails, the process of S106 is executed.

When the transmission / reception counter 16 determines that transmission is successful in the process of step S104 described above, the transmission / reception counter 16 adds 1 to the number of successful frame transmissions of the destination address corresponding to the corresponding transmission channel in the neighborhood communication device management table 17 (S105). ..

Further, when the transmission / reception counter 16 is not determined to have succeeded in transmission in the process of step S104 described above, the transmission / reception counter 16 adds 1 to the number of frame transmission errors of the destination address corresponding to the corresponding transmission channel in the neighborhood communication device management table 17. (S106).

On the other hand, the reception frame analysis unit 13 performs the process of step S108 described later if the frame is received in the reception time slot, and ends the process if the frame is not received in the reception time slot (S107).

After receiving the frame, the reception frame analysis unit 13 executes FCS (Frame Check Sequence) (S108). Then, the reception frame analysis unit 13 executes the process of S109 described later if there is no error, and executes the process of S110 if there is an error.

When the transmission / reception counter 16 determines that there is no error in the process of step S108 described above, the transmission / reception counter 16 adds 1 to the number of successful frame receptions corresponding to the transmission channel and destination address of the neighborhood communication device management table 17 (S109). ..

If the transmission / reception counter 16 does not determine that there is no error in the process of step S104 described above, the transmission / reception counter 16 adds 1 to the number of frame reception errors corresponding to the transmission channel and destination address of the neighborhood communication device management table 17. (S110).

As a modification, the processing of steps S107 to S108 may be omitted.

(A-2-2) Frame transmission processing in the occupied slot of the wireless communication device 10. FIG. 5 is a flowchart showing a characteristic operation (frame transmission in the occupied slot) of the wireless communication device according to the first embodiment. When the transmission frame request is input from the transmission / reception control unit 11 to the transmission timing determination unit 14, the following processing is started.

The transmission timing determination unit 14 confirms whether or not the current time slot is a time slot having a transmission right (S201). If the destination address of the transmission request frame is the same as the destination of the time slot in the time slot having the transmission right, the transmission timing determination unit 14 performs the process of the next step S202. Further, the transmission timing determination unit 14 holds the transmission timing determination unit 14 in the transmission buffer until the next time slot having the transmission right, if not applicable.

The transmission timing determination unit 14 uses the destination address and channel information to refer to the transmission right allocation rate in the transmission right allocation rate table TB shown in FIG. 6 to be described later (S202). Further, the transmission timing determination unit 14 also acquires the transmission right allocation rate of the time slot having the next transmission right.

The transmission timing determination unit 14 makes a transmission determination with the probability described in the transmission right allocation rate (S203). If the transmission timing determination unit 14 determines that transmission is performed, the process proceeds to the process of step S205, and if it is determined that transmission is not performed, the process of the next step S204 is performed.

The transmission timing determination unit 14 determines whether or not transmission is possible in consideration of the amount of communication delay (communication delay time) (S204). The transmission timing determination unit 14 determines that transmission is possible when the transmission right allocation rate is low and transmission is not possible and the communication delay amount becomes large. Specifically, the transmission timing determination unit 14 determines that the number of time slots from the current time slot position to the next time slot to which the transmission right is granted is larger than the preset number of time slots threshold value Tn. This is done by making transmission possible at this point. For example, the threshold Tn is set based on the delay allowance.

Further, even if the transmission timing determination unit 14 is smaller than the threshold value Tn, transmission is possible if the transmission right allocation rate of the next time slot is low. For example, if the transmission right allocation rate is lower than this time, or if the next transmission right allocation rate is lower than a predetermined value, transmission is possible. Further, the transmission timing determination unit 14 may use the shared slot as the time slot having the next transmission right.

The transmission timing determination unit 14 performs the processing of S105 if the transmission is possible, and ends the processing if the transmission is impossible, by determining whether or not the transmission is possible in consideration of the transmission delay amount.

Within the designated time slot, a frame is input to the wireless transmission unit 15 by the transmission timing determination unit 14, and the wireless transmission unit 15 performs wireless transmission (S205).

The transmission timing determination unit 14 updates the transmission right allocation rate using the transmission error rate for the corresponding destination address and transmission channel (S206). If the frame is transmitted in the shared slot, this process may be omitted.

(A-2-3) Operation Example of Wireless Communication Device 10 Next, an operation example of the wireless communication device 10 at the time of the transmission right allocation rate table of FIG. 6 and the time slot and allocation channel shown in FIG. 7 will be described.

FIG. 6 is a diagram showing a configuration example of a transmission right allocation rate table according to the first embodiment. In FIG. 6, the transmission right allocation rate table TB shows a “destination address” indicating the destination (destination) of a frame, a “transmission channel” indicating a channel used for frame transmission, and a “transmission error rate” indicating a packet transmission error rate to the destination. The items of "transmission error rate" and "transmission right allocation rate" indicating the transmission right allocation rate are shown. In FIG. 6, the transmission right allocation rate table TB shows that the transmission right allocation rate is 100% when the transmission error rate is 0%, and the transmission right allocation rate is 90%, 80%, 50 as the transmission error rate increases. It is configured to decrease by%, 20%, and so on.

FIG. 7 is a diagram showing an example of allocating a time slot according to the first embodiment. In FIG. 7, 16 time slots of “0” to “15” are shown as an example.

In the following, for the sake of brevity, it is assumed that there is a transmission request in all time slots. Further, the value of the threshold value Tn of the number of time slots until the next time slot having the transmission right shown in the process of step S203 described above is set to "5". Further, in the following, the wireless communication device 10-4 (node 10-4) will be described as an example.

Nodes 10-4 are shared slots when transmitting in time slot 0 and use channel 1. Further, referring to the transmission right allocation rate table TB, since the transmission right allocation rate is 100%, the node 10-4 transmits the frame. Since the transmission was performed in the shared slot, the node 10-4 does not update the neighborhood communication device management table 17.

When node 10-4 transmits in time slot 1, the destination is node 10-1 and the channel is 2. Further, referring to the transmission right allocation rate table TB, the transmission right allocation rate is 20%. If it is determined that the node 10-4 transmits, the node 10-4 transmits in the time slot 1. If it is determined that the node 10-4 cannot transmit, the node 10-4 refers to the next destination. The time slot 4 whose destination has the transmission right to the node 10-1 is channel 1 and has a transmission right allocation rate of 80%. Since the number of time slots from time slot 1 to time slot 4 is 3, which is shorter than Tn, the corresponding frame is put on standby for transmission up to time slot 4. Since the transmission is put on standby, the node 10-4 does not update the neighborhood communication device management table 17.

When node 10-4 transmits in time slot 2, the destination is node 10-2 and the channel is 3. Further, referring to the transmission right allocation rate table TB, the transmission right allocation rate is 90%. If it is determined that the node 10-4 cannot transmit, the node 10-4 refers to the next time slot to which the transmission right is granted. The next time slot with the transmission right is the time slot 7, channel 4, and the transmission right allocation rate is 50%. The number of time slots from the time slot 2 to the time slot 7 is 5, which is Tn or less, but the transmission right allocation rate (the transmission right allocation rate in the time slot 7 (channel 4) is 50%) is smaller than the time slot 2. The time slot that has the right to transmit to the next node 10-2 is 12, which is wider than Tn. Therefore, the node 10-4 transmits in the time slot 2. Depending on the transmission result, the node 10-4 counts up the number of successful frame transmissions or the number of frame transmission errors for the destination address (node 10-2) of the neighborhood communication device management table 17 and the channel 3.

When node 10-4 transmits in time slot 3, the destination is node 10-3 and the channel is 4. Further, referring to the transmission right allocation rate table TB, since the transmission right allocation rate is 100%, the node 10-4 performs transmission. Since the node 10-4 has transmitted, the neighborhood communication device management table 17 is updated in the same manner as the time slot 2.

When node 10-4 transmits in the time slot 4, the destination is node 10-1 and the channel is 1. If it is determined that the node 10-4 cannot transmit, the node 10-4 refers to the next time slot to which the transmission right is granted. The next time slot to which the transmission right is granted is 7 time slots ahead of the time slot 11, which is wider than Tn. Therefore, the node 10-4 determines that transmission is possible in the time slot 4, and transmits the frame. Since the transmission has been performed, the node 10-4 updates the neighborhood communication device management table 17 in the same manner as the time slot 2 according to the transmission result. In the subsequent time slots, the node 10-4 performs the same processing as described above.

In this embodiment, only the wireless communication device 10 (node 10) on the frame transmitting side has been described, but the transmission right allocation rate is notified to the wireless communication device 10 on the receiving side in advance, and time slots for holding transmission are transmitted and received. Matching may be made between wireless communication devices. For example, when the transmission right allocation rate is 50%, it can be realized by setting in advance that transmission is performed only when the time slot number is an odd number. As a result, the receiving node can be put to sleep in the hold time slot, and power saving can be further achieved.

(A-3) Effect of the first embodiment According to the first embodiment, the following effects are obtained.

The wireless communication device 10 (transmission timing determination unit 14) determines whether or not to perform frame transmission in consideration of the time from the present time to the time slot to which the next transmission right is granted and the next transmission error rate. .. This has the effect that the wireless communication system can easily realize interference avoidance in which the delay amount is reduced to a desired value or less.

Further, by matching the time slot for transmission between both communication devices of the link, the effect of saving power can be further obtained.

(B) Second Embodiment Hereinafter, a second embodiment of the wireless communication device, the wireless communication program, and the wireless communication system according to the present invention will be described in detail with reference to the drawings.

(B-1) Configuration of Second Embodiment The configurations of the wireless communication device 10 and the wireless communication system 1 of the second embodiment are also shown with reference to FIGS. 1 to 3 as in the first embodiment. Can be done. In the first embodiment, an effective example is shown when time slots are allocated to one link at intervals (FIG. 7), but in the second embodiment, FIG. 8 described later for one link is shown. An example that is effective when consecutive time slots are allocated as shown in. In FIG. 8, in addition to the configuration of FIG. 7, the number of remaining time slots indicating how many continuous slots remain at a certain destination (1 link) is added.

Hereinafter, the configuration of the wireless communication device 10 of the second embodiment will be described focusing on the difference from the first embodiment (transmission timing determination unit 14).

When the transmission timing determination unit 14 of the second embodiment fails in the transmission determination of the frame to a certain destination, the transmission timing determination unit 14 refers to the number of remaining time slots and confirms whether the time slots of the same destination have an afterimage. The transmission timing determination unit 14 is different from the first embodiment in that the frame transmission is controlled according to the afterimage time slot. The detailed operation of the transmission timing determination unit 14 of the second embodiment will be described in the section of operation.

(B-2) Operation of the Second Embodiment Next, the operation of the wireless communication system 1 of the second embodiment having the above configuration will be described with reference to the drawings. In this embodiment, the transmission operation of each wireless communication device 10 constituting the wireless communication system 1 has a feature. Therefore, the transmission operation of the wireless communication device 10 will be described below.

(B-2-1) Frame transmission processing in the occupied slot of the wireless communication device 10 FIG. 9 is a flowchart showing a characteristic operation (frame transmission in the occupied slot) of the wireless communication device according to the second embodiment. Similar to the first embodiment, when the transmission frame request is input from the transmission / reception control unit 11 to the transmission timing determination unit 14, the following processing is started.

The transmission timing determination unit 14 performs a process of confirming whether or not the current time slot is a time slot having a transmission right, as in step S201 described above (S301).

The transmission timing determination unit 14 makes a transmission determination in the same manner as in the processes of steps S202 and S203 described above (S302). If the transmission timing determination unit 14 determines that transmission is performed, the process proceeds to the process of step S304, and if it is determined that transmission is not performed, the process of the next step S303 is performed.

The transmission timing determination unit 14 refers to the number of remaining time slots and confirms whether or not the next time slot has a transmission right to the corresponding destination address (S303). If the transmission timing determination unit 14 determines that the transmission right exists, the process proceeds to the process of step S301, and if it determines that the transmission right does not exist, the process of the next step S304 is performed.

Within the time slot designated by the transmission timing determination unit 14, the frame is input to the wireless transmission unit 15, and the wireless transmission unit 15 performs wireless transmission to the destination (S304).

When the transmission process of step S304 is completed, the transmission timing determination unit 14 ends a series of processes, and when a transmission error occurs, performs the process of the next step S306 (S305).

The transmission timing determination unit 14 determines whether or not the number of frame retransmissions exceeds the preset upper limit of the number of retransmissions at the time of transmission error (S306). If the transmission timing determination unit 14 exceeds the upper limit of the number of retransmissions, the series of processes is terminated, and if not, the process proceeds to the process of step S301 described above (retransmission process).

(B-2-2) Operation Example of Wireless Communication Device 10 Next, when the time slot shown in FIG. 8 is assigned to the nodes 10-4 and the frame is transmitted using the transmission right allocation rate table TB of FIG. A specific example is shown.

When the node 10-4 transmits using the time slot 1, the destination is the node 10-1, the channel is 2, and the transmission right allocation rate is 20% in the time slot 1. Further, since the number of remaining slots is 2, the nodes 10-4 can hold the transmission. If it is determined that the node 10-4 cannot transmit, the node 10-4 suspends the transmission until the time slot 2.

When the node 10-4 transmits using the time slot 2, in the time slot 2, the destination is the node 10-1, the channel is 3, and the transmission right allocation rate is 100%. Therefore, the nodes 10-4 perform transmission.

If a transmission error occurs in the transmission of the node 10-4 through the time slot 2, the node 10-4 determines whether or not transmission is possible in the time slot 3 where the next destination is the time slot of the node 10-1. Since the number of remaining slots in the time slot 3 is 0, the nodes 10-4 perform transmission.

When the node 10-4 transmits using the time slot 5, in the time slot 5, the destination is the node 10-3, the channel is 2, and the transmission right allocation rate is 80%. Further, since the number of remaining slots is 0, the nodes 10-4 are set to perform transmission in this slot. If a transmission error occurs in the time slot 5 of the node 10-4, the next destination will transmit in the time slot to the node 10-3, but if the delay amount becomes large, the node 10-4 should transmit in the shared slot 8. May be.

The same processing as above is performed in the subsequent time slots. As a modification, transmission may be suspended in the time slot having the lowest transmission right allocation rate among the consecutive time slots assigned to the same link.

(B-3) Effect of Second Embodiment According to the second embodiment, the following effects are exhibited in addition to the effect of the first embodiment.

The wireless communication device 10 (transmission timing determination unit 14) allocates time slots continuously to one link, and among these, the time slot having a high packet discard rate is not used for transmission. Compared with the embodiment, the effect that the quality of the transmission delay amount can be easily suppressed to a desired value or less can be further obtained. In particular, it is effective to apply the wireless communication device 10 of the second embodiment during multi-hop communication.

For example, the wireless communication system 1 shown in FIG. 2 is a multi-hop network system, which has a route of node 10-4, node 10-3, and node 10-1, and node 10-5, node 10-3, and node 10-. A case where data is collected from each node 10 (wireless communication device 10) to the node 10-1 by the route 1 will be described as an example. In the case of such a configuration, after collecting data at the node 10-3 as shown in FIG. 10, a time slot is allocated so as to be transmitted from the node 10-3 to the node 10-1. That is, if the node 10-4 and the node 10-5 complete the data transmission to the node 10-3 by the time slot 5, the delay amount is reduced. The number of continuous slots may be variable, such as increasing when the error rate of each link is high.

1 ... wireless communication system, 5 ... network management device, 7 ... time slot, 8 ... shared slot, 10 ... wireless communication device, 11 ... transmission / reception control unit, 12 ... wireless reception unit, 13 ... reception frame analysis unit, 14 ... transmission Timing determination unit, 15 ... wireless transmission unit, 16 ... transmission / reception counter, 17 ... neighborhood communication device management table, TB ... transmission right allocation rate table.

Claims (7)

In a wireless communication device that adopts a time-division multiple access method and changes the channel for each time-division time slot.
A storage means for storing at least information on the data transmission destination, the number of successful transmissions for each channel used, and the number of transmission errors.
When transmitting data to another wireless communication device, the transmission error rate derived from the information stored in the storage means, and the number of time slots from the current time slot position to the next time slot to which the transmission right is granted. A wireless communication device comprising a transmission timing determining means for selecting the time slot for data transmission from the assigned transmittable time slots based on a certain communication delay time. The present invention is characterized in that the time slots are continuously assigned to the same destination, and the transmission timing determining means selects the time slots to be transmitted in the continuous time slots. The wireless communication device according to 1. The wireless communication device according to claim 1 or 2, wherein the transmission timing determining means selects the time slot so that the communication delay time is equal to or less than a predetermined value. The wireless communication device according to any one of claims 1 to 3, wherein the time slot can share a part of the time slot assigned to each destination with other destinations. The time slot is any one of claims 1 to 4, wherein an extra time slot is allocated to a specific destination each time the transmission error rate to the specific destination reaches a predetermined error rate . The wireless communication device described in. A computer installed in a wireless communication device that adopts a time-division multiple access method and changes the channel for each time-division time slot.
A storage means for storing at least information on the data transmission destination, the number of successful transmissions for each channel used, and the number of transmission errors.
When transmitting data to another wireless communication device, the transmission error rate derived from the information stored in the storage means, and the number of time slots from the current time slot position to the next time slot to which the transmission right is granted. A wireless communication program characterized in that it functions as a transmission timing determining means for selecting the time slot for data transmission from the assigned transmittable time slots based on a certain communication delay time. In a wireless communication device system composed of multiple wireless communication devices,
A wireless communication device system, wherein the wireless communication device according to claim 1 to 5 is applied as the wireless communication device.

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