JP2024104597A - COMMUNICATION DEVICE, COMMUNICATION METHOD, COMMUNICATION PROGRAM, AND COMMUNICATION SYSTEM - Google Patents

Abstract

[Problem] Suppress delays in data communication. [Solution] A determination unit determines the timing of data communication and the wireless frequency to be used for the data communication based on a determination rule using a first hop number. A communication control unit controls wireless data communication at the determined timing and the determined frequency. If a first condition is satisfied, the determination unit determines the wireless frequency to be used for data communication from the device itself to a first communication destination that is another communication device one hop away based on a determination rule using the first hop number. If a second condition is satisfied, the determination unit determines the wireless frequency to be used for data communication to the second communication destination based on a determination rule using the first hop number and a second hop number from a concentrator of a second communication destination that is two or more hops away from the device itself. [Selected Figure] Figure 9

Description

Embodiments of the present invention relate to a communication device, a communication method, a communication program, and a communication system.

In time division multiplexing wireless communications, it is desirable to suppress interference caused by multiple nodes (communication devices) transmitting data at the same time. For example, a technique has been proposed that suppresses interference within a network by adjusting the time of the slot frame, the unit of the communication schedule, in advance to match the size of the network. A method has also been proposed that uses the number of hops to determine the timing of data communication.

S. Duquennoy, “Orchestra: Robust Mesh Networks Through Autonomously Scheduled TSCH”, <URL: https://dl.acm.org/doi/10.1145/2809695.2809714>

However, with conventional technology, delays in data communication could occur.

The present invention aims to provide a communication device, a communication method, a communication program, and a communication system that can reduce delays in data communication.

The communication device of the embodiment includes a determination unit and a communication control unit. The determination unit determines the timing of data communication by time division multiplexing and the radio frequency to be used for the data communication based on a predetermined decision rule common to a plurality of communication devices using a first hop number from a specific communication device among a plurality of communication devices included in a time division multiplexing communication system. The communication control unit controls the data communication by radio at the determined frequency at the determined timing. When a first condition is satisfied, the determination unit determines the radio frequency to be used for the data communication to a first communication destination one hop away based on the decision rule using the first hop number, and when a second condition different from the first condition is satisfied, the determination unit determines the radio frequency to be used for the data communication to the second communication destination based on the decision rule using the first hop number and a second hop number from the specific communication device to a second communication destination two or more hops away.

FIG. 1 is a diagram showing an example of the configuration of a communication system according to a first embodiment. FIG. 2 is a block diagram showing the functional configuration of a concentrator. A diagram showing a unit of scheduling. FIG. 2 is a block diagram showing the functional configuration of a node. FIG. 1 shows timing determined in a slot frame. FIG. 1 shows timing determined in a slot frame. FIG. FIG. FIG. FIG. FIG. 11 is a flowchart showing the flow of a communication process. FIG. 2 is a diagram showing an example of the configuration of a communication system according to a second embodiment of the present invention. FIG. 2 is a block diagram showing the configuration of a node. FIG. 13 is a diagram showing an example of the configuration of a communication system according to a third embodiment. FIG. 2 is a block diagram showing the functional configuration of a concentrator. FIG. 2 is a block diagram showing the configuration of a node. FIG. 2 is an explanatory diagram showing an example of a hardware configuration.

Below, preferred embodiments of a communication device, a communication method, a communication program, and a communication system are described in detail with reference to the accompanying drawings.

First Embodiment
FIG. 1 is a diagram showing an example of the configuration of a communication system 1 according to the present embodiment.

The communication system of this embodiment includes a concentrator 200, a plurality of nodes _100.1 to _100.5 , and a network 300. Since the nodes _100.1 to _100.5 have the same configuration, they will be simply referred to as node 100 when there is no need to distinguish them. The node 100 and the concentrator 200 are examples of communication devices. Furthermore, when the node 100 and the concentrator 200 are collectively described without distinction, they may be referred to as communication devices.

The concentrator 200 and the nodes 100, which are the communication devices included in the communication system 1, perform time division multiplexing wireless communication. Time division multiplexing wireless communication is sometimes called multi-hop wireless communication. In other words, the communication system 1 is a wireless multi-hop network composed of the concentrator 200 and multiple nodes 100.

The concentrator 200 configures a wireless multi-hop network together with the nodes _100.sub.1 to _100.sub.5 . Wireless communication methods used in the wireless multi-hop network include WiFi (registered trademark), Bluetooth (registered trademark), IEEE 802.15.4, etc. Control methods for the wireless multi-hop network include CTP (Collection Tree Protocol) and RPL (IETF RFC 6550), etc. The wireless communication methods and the control methods for the wireless multi-hop network are not limited to these.

The concentrator 200 corresponds to a specific communication device among multiple communication devices included in a time division multiplexing communication system. The concentrator 200 is a communication device that performs various controls and data aggregation in a wireless multi-hop network. The concentrator 200 is sometimes referred to as a root node.

The number of nodes 100 (node count) constituting the wireless multi-hop network with the concentrator 200 is one or more. The upper limit of the number of nodes is determined by the wireless communication method adopted, the restrictions of the upper layer protocol of the wireless communication method, and requirements such as power consumption if the node 100 is battery-powered. As an example, FIG. 1 shows five nodes 100, nodes 100 ₁ to 100 _5. However, the number of nodes 100 constituting the wireless multi-hop network is not limited to five.

The concentrator 200 may be connected to an external network other than the wireless multi-hop network that includes the network 300. There may be two or more external networks. The concentrator 200 does not have to be connected to an external network. The network 300 may be any network, such as a local network, a field area network, or the Internet. The connection to the network 300 may be wired, wireless, or a combination of wired and wireless.

1 shows an example of a wireless multi-hop network topology that is a linear topology with a single path from a concentrator 200, which is a root node, to a node 100, which is a leaf node. A leaf node is a node 100 that is the farthest from the concentrator 200, and in FIG. 1, node _100-5 corresponds to a leaf node.

In the linear topology, a wireless multi-hop network is configured such that each node 100 has one or less other nodes 100 as its parent node. For example, node 100 ₁ has the concentrator 200 as its parent node and does not have any other nodes 100 as its parent node, but nodes 100 ₂ to 100 ₅ each have one other node 100 as their parent node.

Also, a wireless multi-hop network is configured such that each node 100 has one or less other nodes 100 as its child nodes. For example, node 100 ₅ is a leaf node and does not have other nodes 100 as its child nodes, but nodes 100 ₁ to 100 ₄ each have one other node 100 as its child node.

The leaf node is equipped with, for example, a sensor and an actuator. The leaf node transmits sensor data acquired by the sensor to the parent node via multi-hop communication, thereby transmitting the data to the concentrator 200. In this case, the concentrator 200 collects the sensor data acquired by the leaf node. The concentrator 200 also transmits control information and parameter setting information for the sensor and actuator mounted on the leaf node to the child node via multi-hop transmission, thereby transmitting the information toward the leaf node. Through these processes, the concentrator 200 is configured to be able to control the leaf node. For example, when the leaf node is used for dam management, the concentrator 200 controls the opening and closing of the water gates installed in the dam.

Next, we will explain an example of the functional configuration of the concentrator 200.

Figure 2 is a block diagram showing an example of the functional configuration of the concentrator 200. The concentrator 200 includes a memory unit 20A, a communication unit 20B, a communication unit 20C, an application 20D, a determination unit 20E, and a communication control unit 20F.

Each of the above units (application 20D, decision unit 20E, communication control unit 20F) is realized, for example, by one or more processors. For example, each of the above units may be realized by having a processor such as a CPU (Central Processing Unit) execute a program, i.e., by software. Each of the above units may be realized by a processor such as a dedicated IC (Integrated Circuit), i.e., by hardware. Each of the above units may be realized by using a combination of software and hardware. When multiple processors are used, each processor may realize one of the units, or two or more of the units.

The memory unit 20A stores various data used by the concentrator 200.

For example, the storage unit 20A stores node information. The node information is information about the connected nodes 100. For example, the node information includes, for all nodes 100 in the wireless multi-hop network, information about the node 100 or concentrator 200 (parent node) to which the node 100 is connected, the average Received Signal Strength Indicator (RSSI) between the connection destination, and the remaining battery power. The node information may further include other information about each connection destination, and may include some information about the connection destination, the average RSSI, and the remaining battery power.

The storage unit 20A is required to store at least the node information of the node 100 (node 100 ₁ in the example of FIG. 1 ) that is directly connected to the concentrator 200. The storage unit 20A may store information of all or some of the nodes 100 in the wireless multi-hop network in addition to the node 100 that is directly connected to the concentrator 200.

These node information items are stored in the memory unit 20A by the communication control unit 20F, which will be described later. When disconnection of the node 100 is confirmed by a live/dead check or the like, the communication control unit 20F may delete the node information of the node 100 that has been confirmed to be disconnected and that is stored in the memory unit 20A.

The memory unit 20A can be configured with any commonly used storage medium, such as a flash memory, a memory card, a RAM (Random Access Memory), a HDD (Hard Disk Drive), or an optical disk.

The communication unit 20B communicates with other nodes 100 in the wireless multi-hop network. The communication unit 20C is used for communication with the network 300.

The communication unit 20C is a communication function for connecting to the network 300. The communication unit 20C mainly transmits and receives application data to and from the network 300, and communicates to maintain a connection with the network 300. When the concentrator 200 is configured not to connect to the network 300, the concentrator 200 may not be configured to include the communication unit 20C.

Application 20D executes a predetermined application process. The application process may be any process. Examples of application processes include acquiring and transmitting sensor data, controlling actuators, and transferring messages to other devices.

For example, application 20D generates and transmits application data addressed to node 100 in the wireless multi-hop network and application data addressed to network 300. Application 20D may also receive application data from node 100. For example, application 20D may generate and transmit application data for operating an actuator provided in node 100 and changing the settings of node 100. For example, application 20D may also receive sensor data acquired by a sensor provided in node 100, and transmit the sensor data together to network 300.

The determination unit 20E determines the timing of data communication by time division multiplexing and the radio frequency to be used for the data communication based on a determination rule using the first hop number from the concentrator 200 among the multiple communication devices (node 100, concentrator 200) included in the time division multiplexing communication system 1.

The details of the timing determination process and frequency determination process performed by the determination unit 20E are similar to those performed by the determination unit of node 100, and will be described in detail below.

The communication control unit 20F controls communication using the communication units 20B and 20C. For example, the communication control unit 20F configures, manages, and maintains the wireless multi-hop network. To configure the wireless multi-hop network, the communication control unit 20F advertises the wireless multi-hop network to the surrounding nodes 100 (hereinafter, surrounding nodes) periodically, randomly, or according to certain rules or manual operations. This advertisement is performed by transmitting data called a beacon or a control message.

When the communication control unit 20F receives a connection request from a peripheral node to the wireless multi-hop network, it controls the connection of the peripheral node according to a predetermined procedure. The communication control unit 20F may perform authentication processing with the peripheral node during this connection processing, and permit the connection of the peripheral node if authentication is successful. The communication control unit 20F transmits beacons or control messages, etc. to the connected node 100 at a predetermined timing, maintains synchronization of the internal clocks of the concentrator 200 and the node 100, and checks whether they are alive or dead.

The communication control unit 20F stores in the storage unit 20A the node information of the node 100 (node 100 ₁ in the example of FIG. 1 ) that is directly connected to the concentrator 200. If disconnection of the node 100 is confirmed by a live/dead check or the like, the communication control unit 20F may delete the information stored in the storage unit 20A. In addition to the node 100 that is directly connected to the concentrator 200, the node information of all or some of the nodes 100 in the wireless multi-hop network may be stored in the storage unit 20A.

The communication control unit 20F controls wireless communication using a time division multiplexing method. When the wireless communication method is IEEE 802.15.4, the time division multiplexing method may be TSCH (Time-Slotted Channel Hopping), but other control methods may also be used. In the communication system 1, the scheduling unit of the communication schedule in time division multiplexing is set in advance. The communication control unit 20F performs data communication by periodically repeating the scheduling unit.

Figure 3 is a diagram showing an example of a scheduling unit. Figure 3 shows an example in which a slot frame is used as the scheduling unit. A slot frame is an example of a scheduling unit in time division multiplexing. The scheduling unit is not limited to this. For example, the scheduling unit may be a superframe that includes a certain number of slot frames.

A slot frame contains multiple slots. A slot represents the timing of data communication.

Figure 3 shows an example in which a slot frame consisting of three consecutive slots SL0, SL1, and SL2 is used as a scheduling unit. The length of a slot is a fixed time length. The time length of a slot may be any length, for example, 10 ms, 50 ms, or 100 ms. However, the slots in a slot frame are assumed to be of equal length. In other words, if the length of the first slot is 10 ms, the remaining slots are also each 10 ms long. In Figure 3, the slot frame contains three consecutive slots, but the number of slots contained in one slot frame is not limited to three. A slot frame must contain at least two slots.

The configuration of the slot frame used in communication system 1 is assumed to be common between the concentrator 200 and the node 100 included in communication system 1. In this embodiment, a form in which the slot frame includes three consecutive slots is described as an example. The concentrator 200 and the node 100 described later perform data communication by periodically repeating three consecutive slots included in the slot frame.

Each slot included in the slot frame is assigned by the determination unit 20E as either a transmission slot, a reception slot, or a sleep slot. The timing of data communication is determined by this assignment process. The determination unit 20E also determines the frequency to be used for each slot. The communication control unit 20F controls wireless data communication at the determined frequency at the timing determined by the determination unit 20E.

The control process of data communication by the communication control unit 20F using the timing and frequency determined by the determination unit 20E is similar to the control process of data communication by the communication control unit of the node 100 using the timing and frequency. Therefore, the control process of data communication by the communication control unit 20F using the timing and frequency determined by the determination unit 20E will be described in detail later.

Next, we will explain the configuration of node 100.

Figure 4 is a block diagram showing an example of the functional configuration of node 100.

The node 100 includes a memory unit 10A, a communication unit 10B, an application 10D, a determination unit 10E, and a communication control unit 10F.

Each of the above units (application 10D, decision unit 10E, communication control unit 10F) is realized, for example, by one or more processors. For example, each of the above units may be realized by having a processor such as a CPU execute a program, i.e., by software. Each of the above units may be realized by a processor such as a dedicated IC, i.e., by hardware. Each of the above units may be realized by using a combination of software and hardware. When multiple processors are used, each processor may realize one of the units, or two or more of the units.

Note that node 100 may also be configured to include additional sensors, actuators, etc.

The memory unit 10A stores various data used by the node 100. For example, the memory unit 10A stores information about other connected devices (concentrator 200, other nodes 100). The memory unit 10A can be configured with any commonly used storage medium, such as a flash memory, a memory card, a RAM, a HDD, or an optical disk.

The communication unit 10B communicates with other nodes 100 or the concentrator 200 in the wireless multi-hop network.

Application 10D executes a predetermined application process. The application process by application 10D may be any process. For example, the application process by application 10D is a process corresponding to application 20D of concentrator 200. Specifically, the application process by application 10D is acquisition and transmission of sensor data, control of actuators, and transfer of messages to other communication devices, etc.

The determination unit 10E, like the determination unit 20E of the concentrator 200, determines the timing of data communication by time division multiplexing and the radio frequency to be used for the data communication based on a determination rule using the first hop number from the concentrator 200 among the multiple communication devices (node 100, concentrator 200) included in the time division multiplexing communication system 1.

The communication control unit 10F controls communication using the communication unit 10B. For example, when the communication control unit 10F recognizes the existence of a wireless multi-hop network by receiving a beacon or the like, it transmits a connection request to other nodes 100 in the wireless multi-hop network. The connection process differs depending on the wireless communication method used and the control method of the wireless multi-hop network. For example, the communication control unit 10F transmits and receives several control messages and, in some cases, performs authentication processing, and if these are successful, it can connect to any device (node 100, concentrator 200) in the wireless multi-hop network. The node 100 may be directly connected to the concentrator 200 or may be connected to another node 100.

When node 100 connects to the wireless multi-hop network, it sends and receives control messages that allow node 100 to recognize where it is located in the wireless multi-hop network.

₁ recognizes that it is directly connected to the concentrator 200 and is located at the first hop in the wireless multi-hop network as viewed from the concentrator 200. Also, node 100 ₅ recognizes that it is connected to node 100 ₄ and is located at the fifth hop in the wireless multi-hop network as viewed from the concentrator 200. Such information related to the connection of the wireless multi-hop network is stored, for example, in the storage unit 10A. For example, node 100 ₂ stores the following information in the storage unit 10A.

Destination node (parent node): Node 100 ₁
Distance from the concentrator 200 (number of first hops): 2
・Recent average RSSI with the connection destination: -65 dBm

The communication control unit 10F transmits all or part of the information stored in the memory unit 10A to the connection destination by a control message or the like. The communication control unit 10F also receives similar information from the node 100 connected to itself. The received information may be further transmitted to its connection destination.

The communication control unit 10F recognizes the slot frame, which is the scheduling unit of the communication schedule used in the wireless multi-hop network, from the received control message or by manual setting. Then, like the communication control unit 20F of the concentrator 200, the communication control unit 10F controls wireless data communication at the timing determined by the determination unit 10E of the node 100 and at the frequency determined by the determination unit 10E.

First, we will explain the details of the timing and frequency determination process performed by the determination unit 20E of the concentrator 200 and the determination unit 10E of the node 100.

The determination unit 20E and the determination unit 10E determine the timing of data communication by time division multiplexing and the radio frequency to be used for the data communication based on a decision rule using the first hop number from the concentrator 200 among the multiple communication devices (node 100, concentrator 200) included in the time division multiplexing communication system 1.

The first hop count is the number of hops from the concentrator 200 to the own device. If the own device is the concentrator 200, the first hop count is 0 (zero). If the own device is a node 100, the first hop count is the number of hops between each node 100.

The decision rule is a predefined rule that is common to all communication devices included in the communication system 1.

The decision rules include rules that represent the communication direction. The communication direction is either the upstream direction, in which data is communicated from a child node to a parent node, or the downstream direction, in which data is communicated from a parent node to a child node. In other words, the decision rules include rules that represent either the upstream or downstream communication direction. A decision rule that includes a rule that represents the upstream direction as the communication direction is a rule specific to upstream data communication. A decision rule that includes a rule that represents the downstream direction as the communication direction is a rule specific to downstream data communication.

The decision rules further include rules for determining timing and rules for determining frequency. The decision units 20E and 10E determine the timing and frequency based on the decision rules.

First, we will explain the process of determining the timing of data communication by the determination unit 20E and the determination unit 10E.

The determination unit 20E and the determination unit 10E determine the timing of data communication based on a decision rule using the first hop count and the number of slots, which is the number of multiple slots included in the slot frame and represents the timing of data communication.

The determination unit 20E and the determination unit 10E determine the timing of data communication by assigning, to each of the multiple slots included in the slot frame, one of a transmission slot used for data transmission, a reception slot used for data reception, and a sleep slot in which no data transmission or reception is performed, based on a determination rule.

In other words, the determination unit 20E and the determination unit 10E determine the timing of data communication by assigning either a transmission slot, a reception slot, or a sleep slot to each of the multiple slots included in the slot frame based on a determination rule using the first hop count and the number of slots included in the slot frame.

In detail, the determination unit 20E and the determination unit 10E determine the timing by determining the slot number of the slot to be the transmission slot, the slot number of the slot to be the reception slot, and the slot number of the slot to be the sleep slot among the multiple slots included in the slot frame.

The slot number is information that indicates the position of each slot within the slot frame. In the following, the slot position is represented by the slot number starting from 0, such as 0, 1, ..., N-1. N represents the number of slots.

As explained using FIG. 3, in this embodiment, an example will be explained in which a slot frame consisting of three consecutive slots SL0, SL1, and SL2 is used as a scheduling unit. The slot number of slot SL0 is "0", the slot number of slot SL1 is "1", and the slot number of slot SL2 is "2".

The determination unit 20E and the determination unit 10E determine the slot number according to the rules indicating the communication direction indicated in the determination rules.

First, we will explain the timing determination process when the rule indicating the communication direction included in the determination rule indicates the "uplink direction." In this case, the determination unit 20E and the determination unit 10E determine the slot number of the transmission slot using the following formula (1).

(H+SL _S ) mod N=N-1...Formula (1)

In formula (1), H represents the first hop number. When the own device is the concentrator 200, the first hop number is 0 (zero). When the own device is the node 100, the first hop number H is the hop number from the concentrator 200 of the node 100. In formula (1), N represents the number of slots. In this embodiment, as shown in FIG. 3, a case where the number of slots included in the slot frame is 3 will be described as an example. Therefore, in this embodiment, N represents "3". SL _S represents the slot number of the transmission slot. As shown in FIG. 3, in this embodiment, the slot number is either "0" representing slot SL0, "1" representing slot SL1, or "2" representing slot SL2.

Then, the determination unit 20E and the determination unit 10E determine the slot immediately before the determined transmission slot as the reception slot from the child node that is one hop more. The determination unit 20E and the determination unit 10E also determine the slot immediately after the determined transmission slot as the reception slot from the parent node that is one hop less.

In particular, the determination units 20E and 10E use the slot number of the determined transmission slot to determine the slot numbers SL _R1 and SL _R2 of the two reception slots according to the following equations (2) and (3).

SL _R1 = (SL _S -1) mod N...Formula (2)
SL _R2 = (SL _S +1) mod N...Formula (3)

In the formulas (2) and (3), _{SL_S} represents the slot number of the transmission slot, and N is the same as in the formula (1) above.

In this way, the determination unit 20E and the determination unit 10E calculate the slot number of the transmission slot from the first hop count and the slot number. Also, the determination unit 20E and the determination unit 10E calculate the slot number SL _R (SL _R1 , SL _R2 ) of the reception slot from the slot number of the transmission slot.

When the number of slots is "3", a node 100 other than a leaf node has one transmission slot (slot number) and two reception slots (slot number SL _R1 , slot number SL _R2 ) in the slot frame. Since the concentrator 200 has no parent node, it has one transmission slot (slot number SL _R ) and one reception slot (slot number SL _R1 ) in the slot frame. Since the node 100, which is a leaf node, has no child node, it has one transmission slot (slot number) and one reception slot (slot number SL _R ) in the slot frame.

Then, the determination unit 20E and the determination unit 10E determine, among the slots included in the slot frame, slots to which neither a transmission slot nor a reception slot is assigned as sleep slots. A sleep slot is a slot that puts the entire device into a sleep state to reduce power consumption.

In this case, the timing determination rule included in the legal regulations is a rule that determines the timing for the "upstream" communication direction using the first hop count and the number of slots.

Figure 5 shows an example of timing determined for the slot frame of concentrator 200. Figure 5 shows an example of allocation to each slot of concentrator 200 when the communication direction is "upstream".

In the example shown in FIG. 5, a sleep slot is assigned to slot SL0 in the slot frame of concentrator 200. Therefore, when the current slot at the current timing is slot SL0, communication control unit 20F of concentrator 200 does not transmit or receive data, but puts the entire concentrator 200 into a sleep state to reduce power consumption.

In the example shown in FIG. 5, a receiving slot is assigned to slot SL1 in the slot frame of the concentrator 200. Therefore, when the current slot, which is the current timing, is slot SL1, the communication control unit 20F of the concentrator 200 puts the communication unit 20B into a data receiving standby state. When the node 100 connected to the concentrator 200 transmits data in slot SL1, the communication control unit 20F of the concentrator 200 can receive the data in slot SL1. If it is determined that no data is received in slot SL1, the communication control unit 20F may release the receiving standby state of the communication unit 20B at that point and control it to reduce power consumption. For example, if nothing can be received within a certain period of slot SL1 (for example, 3 milliseconds from the start), the communication control unit 20F may release the receiving standby state of the communication unit 20B.

In the example shown in FIG. 5, a transmission slot is assigned to slot SL2 in the slot frame of concentrator 200. Therefore, when the current slot, which is the current timing, is slot SL2, communication control unit 20F causes communication unit 20B to transmit the transmission data waiting to be transmitted.

Similarly, for node 100, the decision unit 10E of node 100 decides the slot number according to the rule indicating the communication direction "upstream" indicated in the decision rule.

Next, we will explain the timing determination process when the rule indicating the communication direction included in the determination rule indicates the "downstream direction." In this case, the determination unit 20E and the determination unit 10E determine the slot number of the transmission slot by the following formula (4).

(HS) mod N=0...Formula (4)

In formula (2), the meanings of H, S, and N are the same as in the formula above.

Then, the determination unit 20E and the determination unit 10E determine the slot immediately before the determined transmission slot as the reception slot from the parent node that is one hop fewer. The determination unit 20E and the determination unit 10E also determine the slot immediately after the determined transmission slot as the reception slot from the child node that is one hop more. The determination unit 20E and the determination unit 10E then determine, among the slots included in the slot frame, slots to which no transmission slot or reception slot is assigned as sleep slots.

In this case, the timing determination rule included in the legal regulations is a rule that determines the timing for the "downstream" communication direction using the first hop count and the number of slots.

Figure 6 shows an example of timing determined for the slot frame of concentrator 200. Figure 6 shows an example of allocation to each slot of concentrator 200 when the communication rule direction is "downstream".

As shown in FIG. 6, when the communication rule direction included in the legal rules is "downstream", a different allocation is determined than when the communication rule direction shown in FIG. 6 is "upstream".

Similarly, for node 100, the determination unit 10E of node 100 determines the slot number according to the rule indicating the communication rule direction "downstream" indicated in the determination rule.

Next, we will explain the process of determining the wireless frequency to be used for data communication by the determination unit 20E and the determination unit 10E.

When a first condition is satisfied, the determination unit 20E and the determination unit 10E determine the wireless frequency to be used for data communication to the first communication destination based on a determination rule using the first hop count. When a second condition different from the first condition is satisfied, the determination unit 20E determines the wireless frequency to be used for data communication to the second communication destination based on a determination rule using the first hop count and the second hop count of the second communication destination.

The first communication destination is another communication device that is one hop away from the own device. The other communication device that is one hop away refers to another communication device that is located at a point one hop away from the own device.

The second communication destination is another communication device that is two or more hops away from the own device. Another communication device that is two or more hops away means another communication device that is located at a point two or more hops away from the own device. The second hop count is the hop count from concentrator 200 of another communication device that is two or more hops away from the own device.

The determination unit 20E and the determination unit 10E determine the radio frequency to be used for data communication based on a decision rule according to whether the first condition or the second condition is satisfied for the current slot, which is the current timing.

In other words, the determination unit 20E and the determination unit 10E determine, depending on whether the first condition or the second condition is satisfied, as the frequency to be used in the current slot, either a frequency for transmitting data to another communication device one hop away, or a frequency for directly transmitting data to another communication device two or more hops away.

The first condition is satisfied when at least a transmission slot is assigned to the current slot, which is the current timing, and the data to be communicated is transmission data to be transmitted in the communication direction specified in the decision rule.

The second condition is satisfied when at least a transmission slot is assigned to the current slot, which is the current timing, and the data to be communicated is transmission data to be transmitted in the opposite direction to the communication rule direction specified in the decision rule.

As described above, the determination unit 20E and the determination unit 10E determine the timing by determining the slot number of the slot to be the transmission slot, the slot number of the slot to be the reception slot, and the slot number of the slot to be the sleep slot among the multiple slots included in the slot frame according to the communication rule direction indicated in the determination rule. Then, the communication control unit 20F of the concentrator 200 and the communication control unit 10F of the node 100 perform data communication by periodically repeating three consecutive slots included in the slot frame.

The determination unit 20E and the determination unit 10E determine that the first condition is satisfied when the current slot, which changes sequentially by being periodically repeated, is a transmission slot and the data to be communicated is transmission data to be transmitted in the same direction as the communication rule direction.

When it is determined that the first condition is satisfied, the determination unit 20E and the determination unit 10E determine the wireless frequency to be used for data communication to the first communication destination for the current slot based on the determination rule. That is, when the first condition is satisfied, the determination unit 20E and the determination unit 10E determine the wireless frequency to be used for data communication to another communication device one hop away. In other words, when the first condition is satisfied, the determination unit 20E and the determination unit 10E determine the same frequency as the frequency of the current reception slot of the other communication device one hop away as the frequency to be used for the transmission slot.

In detail, when it is determined that the first condition is satisfied, the determination unit 20E and the determination unit 10E determine, for the current slot, one of the multiple frequencies as the frequency to be used for data communication to the first communication destination based on a decision rule using the first hop count and the channel count.

Specifically, when the first condition is satisfied, the determination unit 20E and the determination unit 10E determine, based on the determination rule, the channel number of the frequency to be used for data communication to the first communication destination, which is another communication device one hop away in the same direction as the communication rule direction, as the frequency to be used for the transmission slot, which is the current slot, using the following formula (5). The channel number is a number that identifies the frequency.

CH _S =H mod C...(5)

In formula (5), _{CH_S} represents the channel number of the frequency used in the transmission slot, H is the first hop number, and C is the number of channels, which is the number of available frequencies.

In this case, the statutory rules for frequency determination are those that determine the frequency of the transmission slot using the first hop number and the number of channels for communication in the same direction as the communication direction.

The determination unit 20E and the determination unit 10E can determine the frequency corresponding to the channel number by using frequency information previously stored in the memory unit (memory unit 20A, memory unit 10A). The frequency information is information that associates a channel number with a frequency. The memory unit 20A of the concentrator 200 may store the frequency information in advance. In addition, the concentrator 200 may notify the node 100 of the frequency information in advance, and the notified frequency information may be stored in the memory unit 10A of the node 100 in advance.

As described above, the determination unit 20E and the determination unit 10E assign a transmission slot, a reception slot, or a sleep slot to each of the multiple slots included in the slot frame based on a decision rule using the first hop number and the number of slots. Therefore, slots with the same timing may be assigned to a transmission slot or a reception slot between two communication devices separated by a number of hops that matches the number of slots included in the communication system 1. Therefore, when these two communication devices transmit or receive in the same slot (timing), interference may occur if the same frequency is used in these slots.

Therefore, by having the determination unit 20E and the determination unit 10E determine the frequency according to the first hop count using the above formula (5), it is possible to determine a different frequency according to the first hop count, thereby suppressing interference.

Note that the frequency determined using equation (5) is the same for the transmission slot in each communication device (concentrator 200, node 100) if the connection relationship is not changed and there is no change in the first hop count.

For this reason, the determination unit 20E and the determination unit 10E may further use the slot number of the transmission slot to determine the frequency. In this case, when the first condition is satisfied, the determination unit 20E and the determination unit 10E may determine the channel number of the frequency to be used for data communication to the first communication destination based on the determination rule as the frequency to be used for the transmission slot that is the current slot, using the following formula (6).

CH _S = (S + H) mod C ... (6)

In equation (6), CH _S , H, and C are the same as in equation (5), and S is the slot number of the transmission slot, which is the current slot.

Next, we will explain the process of determining the frequency to be used for the reception slot by the determination unit 20E and the determination unit 10E.

When the current slot is a receiving slot, the determination unit 20E and the determination unit 10E may determine the frequency of the receiving slot by the following process, regardless of whether the first and second conditions are satisfied.

When the current slot is a reception slot and the communication rule direction indicated in the determination rule is "upstream," the determination unit 20E and the determination unit 10E use the following equations (7) and (8) to determine the channel number of the frequency to be used in the reception slot.

CH _R1 = (H+1) mod C...Formula (7)
CH _R2 = (H-1) mod C...Formula (8)

When the current slot is a reception slot and the communication rule direction indicated in the determination rule is "downstream," the determination unit 20E and the determination unit 10E use the following formulas (9) and (10) to determine the channel number of the frequency to be used in the reception slot.

CH _R1 = (H-1) mod C...Formula (9)
CH _R2 = (H+1) mod C...Formula (10)

In the formulas (7) to (10), CH _{3 R1} , CH _{3 R2} , H, and C are the same as those in the above formulas.

Note that equations (7) to (10) are equations used to determine the channel number of the frequency to be used in the reception slot when equation (5) is used to determine the channel number of the frequency to be used in data communication to the first communication destination.

When the channel number of the frequency to be used for data communication to the first communication destination is determined using formula (6), the determination unit 20E and the determination unit 10E may determine the channel number of the frequency to be used in the reception slot using the following formulas (7') to (10').

In detail, when the current slot is a receiving slot and the communication rule direction indicated in the determination rule is "upstream", the determination unit 20E and the determination unit 10E determine the channel number of the frequency to be used in the receiving slot using the following formulas (7') and (8').

CH _R1 = (S _t+1 +H) mod C...Formula (7')
CH _R2 = (S _t-1 +H) mod C...Formula (8')

When the current slot is a reception slot and the communication rule direction indicated in the determination rule is "downstream," the determination unit 20E and the determination unit 10E use the following formula (9') and formula (10') to determine the channel number of the frequency to be used in the reception slot.

CH _R1 = (S _t-1 +H) mod C...Formula (9')
CH _R2 = (S _t+1 +H) mod C...Formula (10')

In formulas (7') to (10'), CH _R1 , CH _R2 , H, and C are the same as in the above formulas. _{S t-1} is the slot number of the transmission slot immediately preceding the current slot. _{S t+1} is the slot number of the transmission slot immediately following the current slot.

By performing the above-mentioned frequency determination process independently in the determination unit 20E of the concentrator 200 and in the determination unit 10E of each of the multiple nodes 100, when the communication rule direction indicated in the determination rule is the "upstream direction" and the transmission slot satisfies the first condition, communication can be performed in the entire wireless multi-hop network according to the communication schedule shown in FIG. 7A. FIG. 7A is a diagram showing an example of a communication schedule.

Furthermore, by performing the above-mentioned frequency determination process independently in the determination unit 20E of the concentrator 200 and the determination unit 10E of each of the multiple nodes 100, when the communication rule direction indicated in the determination rule is "downstream", communication can be performed in the entire wireless multi-hop network according to the communication schedule shown in FIG. 7B. FIG. 7B is a diagram showing an example of a communication schedule.

In the example of Figures 7A and 7B, the number of slots is 3 and the number of channels is 7 or more. In Figures 7A and 7B and the figures described later, the numbers following ch in ch0 to ch6 represent the channel number. In Figures 7A and 7B and the figures described later, "hop count" represents the first hop count.

Each node 100 uses a common decision rule that determines the slot number and frequency according to the first hop count. Therefore, each node 100 can perform scheduling that avoids interference within the wireless multi-hop network without exchanging control messages (negotiations) with other devices.

When the number of slots is smaller than the number of nodes, multiple nodes 100 will communicate data in the same slot. However, in this embodiment, the decision unit 20E and the decision unit 10E schedule to use different frequencies, so interference can be suppressed. Also, a shortage of frequencies can cause multiple nodes 100 to communicate data at the same frequency. However, in the communication system 1 of this embodiment, scheduling can be performed such that the same frequency is used between nodes 100 with a difference in the number of hops equal to the number of channels, which is the number of frequencies, that is, scheduling can be performed such that the same frequency is used between nodes 100 that are far apart on the network. Therefore, in the communication system 1 of this embodiment, interference within the same network can be suppressed.

Next, we will explain the control process of data communication using the timing and frequency determined by the determination unit 20E of the communication control unit 20F, and the control process of data communication using the timing and frequency determined by the determination unit 10E of the communication control unit 10F.

The communication control unit 20F controls wireless data communication at the determined frequency at the timing determined by the determination unit 20E.

When a transmission slot is assigned to the current slot, which is the current timing, the communication control unit 20F causes the communication unit 20B to transmit the transmission data waiting to be transmitted at the frequency determined for that transmission slot.

When a receive slot is assigned to the current slot, which is the current timing, the communication control unit 20F places the communication unit 20B in a state of waiting to receive data at the frequency determined for that receive slot. When the node 100 connected to the concentrator 200 transmits transmission data at that frequency in a slot, the concentrator 200 can receive the data in that receive slot. If it is determined that no data is being received in the receive slot, the communication control unit 20F may release the receive wait state of the communication unit 20B at that point in time and control it to reduce power consumption.

When a sleep slot is assigned to the current slot at the current timing, the communication control unit 20F does not transmit or receive data, but puts the entire concentrator 200 into a sleep state to reduce power consumption.

The communication control unit 10F controls data communication in the same manner as the communication control unit 20F.

In detail, the communication control unit 10F controls wireless data communication at the determined frequency at the timing determined by the determination unit 10E.

When a transmission slot is assigned to the current slot, which is the current timing, the communication control unit 10F causes the communication unit 10B to transmit the transmission data waiting to be transmitted at the frequency determined for that transmission slot.

When a reception slot is assigned to the current slot, which is the current timing, the communication control unit 10F places the communication unit 10B in a state of waiting to receive data at the frequency determined for that reception slot. If it is determined that no data is being received in the reception slot, the communication control unit 10F may cancel the reception waiting state of the communication unit 10B at that point in time and control it to reduce power consumption.

When a sleep slot is assigned to the current slot at the current timing, the communication control unit 10F does not transmit or receive data, but puts the entire node 100 into a sleep state to reduce power consumption.

Here, as described above, the decision rules include rules that indicate either the upstream or downstream communication direction.

Therefore, even when node 100 and concentrator 200 communicate data in the opposite direction to the communication rule direction indicated in the decision rule, the data communication will be performed according to the communication schedule determined based on the communication rule direction.

Figure 8 is an explanatory diagram of an example of a case where data is transmitted in the "downstream" direction, which is the opposite direction of the communication rule direction, according to a communication schedule determined based on the "upstream" communication rule direction indicated in the decision rule.

As shown in FIG. 7A, assume that data is transmitted in the "upstream" direction, which is a communication rule, according to a communication schedule determined based on the "upstream" communication rule direction indicated in the decision rule. In this case, data is transmitted one hop at a time from the downstream node 100 toward the concentrator 200 for each successive slot.

Specifically, data transmitted in the upstream direction from node _100-2 at slot SL0, which is a transmission slot, at the frequency of the channel number of ch2 is received in slot SL0, which is a reception slot of node _100-1 , which is the parent node of node _100-2 . Then, node _100-1 transmits the data received in slot SL0 at the frequency of the channel number of ch1 in slot SL1, which is the next consecutive slot and is assigned as a transmission slot, toward concentrator 200, which is its parent node. Data transmitted in the upstream direction from node _100-1 at slot SL1, which is a transmission slot, at the frequency of the channel number of ch1 is received in slot SL1, which is a reception slot of concentrator 200, which is the parent node of node _100-1 , at the frequency of the channel number of ch1.

In this way, when data is transmitted in the communication rule direction according to the communication schedule determined based on the communication rule direction indicated in the decision rule, data is transmitted one hop at a time for each successive slot.

On the other hand, consider the case where data is transmitted in the opposite direction to the communication rule direction according to a communication schedule determined based on the communication rule direction indicated in the decision rule. Specifically, as shown in FIG. 8, consider the case where data is transmitted in the "downstream" direction, which is the opposite direction to the communication rule direction, according to a communication schedule determined based on the "upstream" communication rule direction indicated in the decision rule.

When transmitting data in the opposite direction to the communication rule direction indicated in the decision rule, the data is transmitted one hop at a time, not for each consecutive slot, but for every two or more consecutive slots. For example, when the number of slots is "3", as shown in FIG. 8, when transmitting data in the opposite direction to the communication rule direction, data is transmitted one hop away every two slots. For this reason, when transmitting data in the opposite direction to the communication rule direction, it takes twice as long to communicate compared to transmitting data in the direction of the communication rule. In other words, in this case, a delay in data communication occurs.

Therefore, in this embodiment, when the determination unit 20E and the determination unit 10E determine that the second condition is satisfied, they determine the wireless frequency to be used for data communication to the second communication destination for the current slot based on the determination rule.

As described above, the second condition is satisfied when at least a transmission slot is assigned to the current slot, which is the current timing, and the data to be communicated is transmission data to be transmitted in the opposite direction to the communication rule direction specified in the decision rule. The second communication destination is another communication device that is two or more hops away from the own device.

That is, when the second condition is satisfied, the determination unit 20E and the determination unit 10E determine the wireless frequency to be used for data communication to another communication device two or more hops away. In other words, when the second condition is satisfied, the determination unit 20E and the determination unit 10E determine the same frequency as the current reception slot frequency of the other communication device two or more hops away as the frequency to be used for the transmission slot.

In detail, when the second condition is satisfied, the determination unit 20E and the determination unit 10E determine, for the current slot, one of the multiple frequencies as the frequency to be used for data communication to the second communication destination based on a decision rule using the first hop count, the second hop count, and the number of channels.

The second hop number is the number of hops from the concentrator 200 of another communication device that is two or more hops away from the own device.

Specifically, when the second condition is satisfied, the determination unit 20E and the determination unit 10E determine, based on the determination rule, the frequency channel number to be used for data communication to the second communication destination, which is another communication device two or more hops away in the opposite direction of the communication rule, as the frequency to be used for the transmission slot, which is the current slot, using the following formula (11).

CH _S = (H + αN) mod C ... (11)

In formula (11), CH _S , H, N, and C have the same meanings as in the above formula. In formula (11), α is an integer equal to or greater than 1. αN represents the second hop count.

The frequency determination rule included in the legal rules in the case shown in equation (11) is a rule that determines the frequency of the transmission slot for communication in the reverse direction of the communication rule direction using the first hop number, the second hop number, and the number of channels.

In other words, when the second condition is satisfied, the determination unit 20E and the determination unit 10E determine, for the current slot, one of the multiple frequencies as the frequency to be used for data communication to the second communication destination based on a decision rule using the first hop count, the second hop count, and the number of channels.

The determination unit 20E and the determination unit 10E may calculate the second hop count based on the number of slots. That is, the determination unit 20E and the determination unit 10E may calculate the multiplication value of the number of slots (N) and α as the second hop count. The value of α may be an integer equal to or greater than 1, and may be a value that allows the device to directly communicate data to a communication device with the second hop count represented by the multiplication value of α and the number of slots (N). For this reason, the value of α may be a value common to all communication devices included in the communication system 1, or may be a different value for some of the communication devices.

When α is "1", the determination unit 20E and the determination unit 10E can determine a frequency at which data can be directly communicated to a communication device N-1 hops away or N-1 hops away. When α is "2", the determination unit 20E and the determination unit 10E can determine a frequency at which data can be directly communicated to a communication device 2N-1 hops away or 2N+1 hops away.

The value of α may be stored in advance in each of the memory unit 10A and the communication unit 20B. In addition, if a value common to all communication devices included in the communication system 1 is used as the value of α, the concentrator 200 may notify each node 100 via a beacon or the like.

The frequency determined using equation (11) is the same for the transmission slot in each communication device (concentrator 200, node 100) if the connection relationship is not changed and there is no change in the first hop count H and the second hop count αN.

For this reason, the determination unit 20E and the determination unit 10E may further use the slot number of the transmission slot to determine the frequency. In this case, when the second condition is satisfied, the determination unit 20E and the determination unit 10E may determine the channel number of the frequency to be used for data communication to the second communication destination based on the determination rule as the frequency to be used for the transmission slot that is the current slot, using the following formula (12).

CH _S = (S+H+αN) mod C...(12)

In equation (12), CH _S , H, α, N, αN, and C are the same as in the above equation. As in the above equation, S is the slot number of the transmission slot, which is the current slot.

When the current slot is a receiving slot, the determination unit 20E and the determination unit 10E may determine the frequency of the receiving slot by the above-described process, regardless of whether the first and second conditions are satisfied, as described above.

In this way, the determination unit 20E and the determination unit 10E determine, depending on whether the first condition or the second condition is satisfied, as the frequency to be used for the transmission slot that is the current slot, either a frequency for transmitting data to another communication device one hop away or a frequency for directly transmitting data to another communication device several hops away. As described above, the first condition is satisfied when at least a transmission slot is assigned to the current slot that is the current timing, and the data to be communicated is transmission data to be transmitted in the communication rule direction specified in the determination rule. As described above, the second condition is satisfied when at least a transmission slot is assigned to the current slot that is the current timing, and the data to be communicated is transmission data to be transmitted in the opposite direction to the communication rule direction specified in the determination rule.

Therefore, when the first condition for transmitting transmission data in the direction of the communication rule specified in the decision rule is satisfied, the decision unit 20E and the decision unit 10E determine a frequency that can be directly transmitted to the first communication destination, which is another communication device one hop away, for the transmission slot for transmitting the transmission data. In other words, when the first condition for transmitting transmission data in the direction of the communication rule specified in the decision rule is satisfied, the decision unit 20E and the decision unit 10E determine a frequency to be used for the current transmission slot for transmitting the transmission data to be the same as the frequency of the current reception slot of the other communication device one hop away.

On the other hand, when the second condition for transmitting transmission data in the opposite direction to the communication rule direction specified in the determination rule is satisfied, the determination unit 20E and the determination unit 10E determine the wireless frequency to be used for data communication to another communication device two or more hops away. In other words, when the second condition is satisfied, the determination unit 20E and the determination unit 10E determine the same frequency as the frequency of the current reception slot of the other communication device two or more hops away as the frequency to be used for the current transmission slot.

In other words, the concentrator 200 and node 100 of this embodiment transmit data directly to another communication device that is two or more hops away and that has a reception slot assigned to a slot with the same timing as the transmission slot, using the same frequency as the frequency determined for the reception slot.

For this reason, when transmitting data in the opposite direction of the communication rule direction according to a communication schedule determined based on the communication rule direction indicated in the decision rule, the concentrator 200 and node 100 of this embodiment can transmit data directly to another communication device several hops away. In other words, the concentrator 200 and node 100 of this embodiment can transmit transmission data directly to another communication device two or more hops away in a single transmission opportunity. Therefore, the concentrator 200 and node 100 of this embodiment can suppress delays in data communication.

The first condition is satisfied when at least a transmission slot is assigned to the current slot, which is the current timing, and the data to be communicated is transmission data to be transmitted in the direction of the communication rule specified in the decision rule, and may further include other elements. Similarly, the second condition is satisfied when at least a transmission slot is assigned to the current slot, which is the current timing, and the data to be communicated is transmission data to be transmitted in the opposite direction to the communication rule direction specified in the decision rule, and may further include other elements.

For example, the first condition may be satisfied when a transmission slot is assigned to the current slot, the data to be communicated is transmission data to be transmitted in the direction of the communication rule or in the opposite direction to the communication rule, and the data to be communicated has not yet been transmitted. In this case, the second condition may be satisfied when a transmission slot is assigned to the current slot, the data to be communicated is transmission data to be transmitted in the opposite direction to the communication rule, and the data to be communicated has already been transmitted at the frequency determined when the first condition was satisfied.

In this case, the determination unit 20E and the determination unit 10E determine a wireless frequency to be used for data communication to the first communication destination when a transmission slot is assigned to the current slot, the data to be communicated is transmission data to be transmitted in the direction of the communication rules or in the opposite direction to the communication rules, and the data to be communicated satisfies the first condition and transmission has not been performed at the determined frequency. Then, the determination unit 20E and the determination unit 10E determine a wireless frequency to be used for data communication to the second communication destination when a transmission slot is assigned to the current slot, the data to be communicated is transmission data to be transmitted in the opposite direction to the communication rules, and transmission has already been performed at the determined frequency when the data to be communicated satisfies the first condition.

By setting the first condition and the second condition as such conditions, when the data to be communicated is transmission data to be transmitted in the opposite direction to the communication rule direction, the determination unit 20E and the determination unit 10E can directly transmit data to both the first communication destination one hop away and the second communication destination two or more hops away. In a wireless multi-hop network, it is possible to transmit transmission data more reliably when transmitting data to a communication device one hop at a time compared to directly transmitting data to another communication device several hops away. Therefore, by the determination unit 20E and the determination unit 10E determining a frequency such that data is directly transmitted to both the first communication destination one hop away and the second communication destination two or more hops away, it is possible to more reliably transmit data to the communication destination.

The determination unit 20E and the determination unit 10E may determine a wireless frequency to be used for data communication to a second communication destination when a transmission slot is assigned to the current slot, the data to be communicated is transmission data to be transmitted in the direction of the communication rule or in the opposite direction to the communication rule, and the data to be communicated satisfies the second condition and transmission at the determined frequency has already been transmitted.

The second condition may be satisfied when a transmission slot is assigned to the current slot, the data to be communicated is transmission data to be transmitted in the opposite direction to the communication rule direction, and the second communication destination is not currently in data communication.

The determination unit 20E and the determination unit 10E may infer whether or not the second communication destination is in data communication from the data transmitted in the direction of the communication rule. Specifically, if the data transmitted in the direction of the communication rule and received from another communication device includes a flag for continuing data transmission, or if the flag is valid, the determination unit 20E and the determination unit 10E may determine that the second communication destination is not in data communication. Furthermore, if these conditions are not met, the determination unit 20E and the determination unit 10E may determine that the second communication destination is not in data communication.

The determination unit 20E and the determination unit 10E may also use the periodic transmission interval of the data periodically transmitted by the second communication destination to infer the transmission timing of the next data transmission by the second communication destination, thereby determining whether the second communication destination is engaged in data communication.

By setting the second condition as such, the determination unit 20E and the determination unit 10E can determine the frequency of the second communication destination so that the transmission data is sent to the second communication destination at a timing when the second communication destination can receive the data, thereby making it possible to avoid interference.

When the first and second conditions as described above are satisfied, the process of determining the frequency of the transmission slot may be performed independently by the determination unit 20E of the concentrator 200 and the determination unit 10E of each of the multiple nodes 100.

In addition, at least one communication device included in the communication system 1 may perform a process of determining the frequency of a transmission slot when the first condition and the second condition are respectively satisfied, and other communication devices may perform a process of determining the frequency of a transmission slot when the first condition is satisfied, regardless of whether the first condition and the second condition are satisfied.

By performing a process of determining the frequency of the transmission slot when at least one communication device included in the communication system 1 satisfies the first and second conditions, transmission data to be transmitted in the reverse direction of the communication rule direction can be transmitted more quickly to a communication device that is a further hop away. Therefore, the concentrator 200 and node 100 of this embodiment can transmit transmission data more quickly to the end node 100 or the end concentrator 200 even when transmitting transmission data in the reverse direction of the communication rule direction.

It is preferable that at least the determination unit 20E of the concentrator 200 among the multiple communication devices included in the communication system 1 performs both the frequency determination process of the transmission slot when the first condition and the second condition are satisfied. Then, for the other communication devices, regardless of whether the first condition and the second condition are satisfied, the frequency determination process of the transmission slot when the first condition is satisfied may be performed.

Next, we will explain a specific example of communication across the entire wireless multi-hop network using the concentrator 200 and the node 100.

It is assumed that the determination unit 20E of the concentrator 200 performs both the frequency determination process when the first and second conditions described above are satisfied. It is also assumed that the determination unit 10E of each of the multiple nodes 100 performs the frequency determination process when the first condition is satisfied, regardless of whether the first and second conditions are satisfied.

In this case, if the communication rule direction indicated in the decision rule is "upstream" and data is transmitted in the "downstream" direction, which is the opposite direction to the communication rule direction, communication can be performed in the entire wireless multi-hop network according to the communication schedule shown in Figure 9.

Figure 9 is a diagram showing an example of a communication schedule. Figure 9 is an explanatory diagram of an example of a case where data is transmitted in the "downstream direction", which is the opposite direction of the communication rule direction, according to a communication schedule determined based on the "upstream direction" communication rule direction indicated in the determination rule. Figure 9 also shows a case where the determination unit 20E of the concentrator 200 performs a process of determining the frequency of the transmission slot when the second condition is satisfied.

As shown in FIG. 8, when data is sent to a first communication destination one hop away in the opposite direction to the communication rule direction indicated in the decision rule, the data is sent one hop at a time, not for each consecutive slot, but for every two or more consecutive slots. For example, if the number of slots is "3", as shown in FIG. 8, when data is sent in the opposite direction to the communication rule direction, data is sent one hop away every two slots, resulting in a delay in data communication.

On the other hand, assume that the determination unit 20E of the concentrator 200 performs a frequency determination process that satisfies the second condition.

9, in slot frame 1, transmission data transmitted from concentrator 200 to node _100-1 , which is one hop away in the "downstream direction" and has a hop count of 1, is transmitted from node _100-1 to node _100-2 , which is one hop away in the "downstream direction" and has a hop count of 2, in slot frame 2. For slot SL2 of slot frame 2, determination unit 20E of concentrator 200 determines channel number 3, which has the same frequency as the frequency of channel number 3 determined for the reception slots of node _100-2 , which is the first hop count of 2 and node _100-4 , which is the first hop count of 4, which are second communication devices two or more hops away.

Therefore, the communication control unit 20F of the concentrator 200 transmits transmission data of a frequency that can be received by each of the node _100-2 , which is two hops away, and the node _100-4 , which is four hops away, at the timing of the transmission slot of the slot frame 2. Therefore, the transmission data transmitted from the concentrator 200 at the timing of the transmission slot of the slot frame 2 can be received by each of the node _100-2 , which is two hops away, and the node _100-4 , which is four hops away.

As a result, the communication device of this embodiment can directly transmit transmission data to a node 100 that is two or more hops away in one timing (slot), thereby reducing delays in data communication.

Figure 10 is a diagram showing an example of a communication schedule. Figure 10 is an explanatory diagram of an example of a case where data is transmitted in the "downstream direction", which is the opposite direction of the communication rule direction, according to a communication schedule determined based on the "upstream direction" communication rule direction indicated in the determination rule. Figure 10 also shows a case where the determination unit 20E of the concentrator 200 performs a process of determining the frequency of the transmission slot when the second condition is satisfied. Figure 10 also shows an example of transmitting transmission data directly from the concentrator 200 to nodes 100 that are 5 hops and 7 hops away.

10, in slot frame 1, transmission data transmitted from concentrator 200 to node _100-1 , which is one hop away in the "downstream direction" and has a hop count of 1, is transmitted from node _100-1 to node _100-2 , which is one hop away in the "downstream direction" and has a hop count of 2, in slot frame 2. For slot SL2 of slot frame 2, determination unit 20E of concentrator 200 determines channel number 6, which has the same frequency as the frequency of channel number 6 determined for the reception slots of node _100-5 , which is the first hop count of 5 and node _100-7 , which is the first hop count of 7, which are second communication devices two or more hops away.

Therefore, the communication control unit 20F of the concentrator 200 transmits transmission data at a frequency that can be received by each of the node ₁₀₀₅ , which is five hops away, and the node ₁₀₀₇ , which is seven hops away, at the timing of the transmission slot of the slot frame 2. Therefore, the transmission data transmitted from the concentrator 200 at the timing of the transmission slot of the slot frame 2 can be received by each of the node ₁₀₀₅ , which is five hops away, and the node _1007, which is seven hops away.

As a result, the communication device of this embodiment can directly transmit transmission data to a node 100 that is two or more hops away in one timing (slot), thereby reducing delays in data communication.

Next, an example of communication processing performed by each of the concentrator 200 and node 100 in this embodiment will be described.

Figure 11 is a flowchart showing an example of the flow of communication processing executed by the concentrator 200. Note that the flow of communication processing executed by the node 100 is similar to the flowchart shown in Figure 11, so the case of the concentrator 200 will be described as an example. Note that in Figure 11, the explanation is given on the assumption that the decision unit 20E of the concentrator 200 has already determined the timing of data communication by assigning either a transmission slot, a reception slot, or a sleep slot to each of the multiple slots based on a decision rule using the first hop count and the number of slots.

The decision unit 20E of the concentrator 200 identifies the communication rule direction indicated in the decision rule (step S300). Next, the decision unit 20E determines whether the current slot is assigned as a receive slot, a transmit slot, or a sleep slot (step S302).

If a transmission slot is assigned to the current slot, the determination unit 20E determines whether there is transmission data to be transmitted in the opposite direction to the communication rule direction identified in step S300 (step S304). For example, the determination unit 20E performs the determination in step S304 by determining whether transmission data for transmission in the opposite direction is stored in the storage unit 20A. For example, the determination unit 20E may determine whether data received from another communication device connected to the communication rule direction side of the own device and destined for another communication device on the opposite direction side is stored in the storage unit 20A, thereby determining whether transmission data for transmission in the opposite direction is stored in the storage unit 20A.

If there is transmission data to be transmitted in the opposite direction (step S304: Yes), proceed to step S306. In step S306, the determination unit 20E determines whether the transmission data has already been transmitted using the frequency determined when the first condition is satisfied (step S306). For example, the determination unit 20E makes the determination in step S306 by determining whether a flag indicating that the transmission data has been transmitted is assigned to the transmission data.

When the determination unit 20E makes a negative determination in step S306 (step S306: No), the process proceeds to step S316, which will be described later. When the determination unit 20E makes a positive determination in step S306 (step S306: Yes), the determination unit 20E determines whether or not the second communication destination is in data communication (step S308). The determination unit 20E identifies Nα, which is the multiplication value of the number of slots and α, as the second hop count of the second communication destination. Then, the determination unit 20E determines whether or not the second communication destination of the identified second hop count is in data communication. For example, the determination unit 20E determines whether or not the second communication destination is in data communication by inferring whether or not the second communication destination is in data transmission using the method described above.

If the determination unit 20E determines that the second communication destination is in data communication (step S308: Yes), the process proceeds to step S320, which will be described later. If the determination unit 20E determines that the second communication destination is not in data communication (step S308: No), the process proceeds to step S310.

In step S310, the determination unit 20E determines the frequency to be used for data communication to the second communication destination as the frequency to be used for the transmission slot, which is the current slot (step S310). In detail, the determination unit 20E determines the frequency using the above formula (11) or formula (12).

Then, the communication control unit 20F controls the communication unit 20B to transmit the transmission data at the frequency determined in step S310 for the current transmission slot (step S312). Note that the communication control unit 20F may delete the transmitted transmission data whose transmission was controlled in step S312 from the storage unit 10A. The communication control unit 20F may also invalidate the flag indicating that the transmission data has been transmitted, which is assigned to the transmission data. Then, this routine ends.

On the other hand, if it is determined in step S304 that there is no transmission data to be transmitted in the opposite direction (step S304: No), the process proceeds to step S314. In step S314, the determination unit 20E determines whether there is transmission data to be transmitted in the communication rule direction identified in step S300 (step S314). For example, the determination unit 20E performs the determination in step S314 by determining whether transmission data to be transmitted in the communication rule direction is stored in the storage unit 20A. For example, the determination unit 20E may determine whether data to be transmitted in the communication rule direction is stored in the storage unit 20A by determining whether data received from another communication device connected to the opposite side of the communication rule direction with respect to the own device and addressed to another communication device on the communication rule direction side is stored in the storage unit 20A.

If it is determined that there is no transmission data to be sent in the direction of the communication rule (step S314: No), proceed to step S320 described below. If it is determined that there is transmission data to be sent in the direction of the communication rule (step S314: Yes), proceed to step S316.

In step S316, the determination unit 20E determines the frequency to be used for data communication to the first communication destination as the frequency to be used for the transmission slot, which is the current slot (step S316). In detail, the determination unit 20E determines the frequency using the above formula (5) or formula (16).

Then, the communication control unit 20F controls the communication unit 20B to transmit the transmission data at the frequency determined in step S316 for the current transmission slot (step S318). The communication control unit 20F then assigns a flag indicating that the transmission data has been transmitted to the transmitted data and stores the data in the storage unit 10A. Then, this routine ends.

On the other hand, if it is determined in step S302 that a sleep slot has been assigned to the current slot, the communication control unit 20F does not transmit or receive data, but puts the entire concentrator 200 into a sleep state to reduce power consumption (step S320). Then, this routine ends.

On the other hand, if it is determined in step S302 that a receiving slot is assigned to the current slot, the determination unit 20E determines the frequency of the transmitting slot of the communication device of the first communication destination one hop upstream in the communication rule direction identified in step S300 as the frequency of the receiving slot (step S322). In detail, if the communication rule direction identified in step S300 is the "upstream direction", the determination unit 20E determines the frequency using the above formula (7) and formula (8). Also, if the communication rule direction identified in step S300 is the "downstream direction", the determination unit 20E determines the frequency using the above formula (9) or formula (10).

Then, the communication control unit 20F performs reception standby and reception processing (step S324). In step S324, the communication control unit 20F sets the frequency of the communication unit 20B to the frequency determined in step S322 for the period of the current reception slot, and sets the communication unit 20B in a state of waiting to receive data. When the node 100 connected to the concentrator 200 transmits data in that slot, the communication control unit 20F of the concentrator 200 can receive the data in that slot. If it is determined that no data is received for a certain period of time within that slot, the communication control unit 20F may cancel the reception standby state of the communication unit 20B at that point, and control the communication unit 20B to reduce power consumption. Then, this routine ends.

As described above, the concentrator 200 of this embodiment includes a determination unit 20E and a communication control unit 20F. The node 100 of this embodiment includes a determination unit 10E and a communication control unit 10F.

At least one of the determination unit 20E and the determination unit 10E determines the timing of data communication by time division multiplexing and the wireless frequency to be used for the data communication based on a predetermined determination rule common to the multiple communication devices, using the first hop count from a specific communication device (concentrator 200) among the multiple communication devices (node 100, concentrator 200) included in the time division multiplexing communication system 1. The communication control unit 20F and the communication control unit 10F control the wireless data communication at the determined frequency at the determined timing.

When the first condition is satisfied, at least one of the determination units 20E and 10E determines a wireless frequency to be used for data communication from the device to the first communication destination, which is another communication device one hop away, based on a decision rule using the first hop count. When the second condition is satisfied, at least one of the determination units 20E and 10E determines a wireless frequency to be used for data communication from the device to the second communication destination, based on a decision rule using the first hop count and the second hop count from the concentrator 200 of the second communication destination, which is two or more hops away from the device.

In this way, the communication device (node 100, concentrator 200) of this embodiment determines the wireless frequency to be used for data communication from the device to a first communication destination one hop away, or the wireless frequency to be used for data communication from the device to a second communication destination two or more hops away, depending on the first and second conditions.

For this reason, the communication device of this embodiment can transmit data directly to a communication destination several hops away depending on the conditions. In other words, the communication device of this embodiment can transmit data toward the leaf node or the concentrator 200 at high speed, thereby suppressing delays in data communication.

Therefore, the communication device of this embodiment can suppress delays in data communication.

The communication system 1 according to this embodiment can employ either an autonomous communication scheduling algorithm based on the number of hops or a centralized communication scheduling algorithm in time division multiplexing wireless communication control.

An autonomous communication scheduling algorithm is an algorithm that does not require negotiation, which is, for example, the exchange of control messages with a communication partner to notify the slots to be used for communication. An autonomous communication scheduling algorithm is easy to implement and can reduce control overhead. By reducing control overhead, the negotiation load can be reduced.

On the other hand, centralized communication scheduling algorithms have control overhead. However, centralized communication scheduling algorithms can flexibly respond to various communication environments because route control can be managed by a device called a concentrator.

Let us assume that multiple nodes 100 transmit data in the same slot (time). In this case, the transmission signals of the multiple nodes 100 may interfere with each other, causing data loss, etc. In an autonomous communication scheduling algorithm and a centralized communication scheduling algorithm, it is necessary to perform scheduling in a way that avoids such interference within the same network.

In this embodiment, a linear topology is adopted in which a single route is formed from the concentrator 200, which is the root node of the wireless multi-hop network, to the leaf nodes. When each node 100 is connected to the wireless multi-hop network, it recognizes the first hop number, which is the number of hops from the concentrator 200 to the node itself. Each node 100 uses this first hop number to determine the slot and frequency, which are the timing for data communication. Each node 100 performs data reception processing in slots in which other nodes 100 (there is one parent node and one child node because of the linear topology) that transmit data to the node itself transmit data.

The communication system 1 of this embodiment can be configured so that multiple nodes 100 use different frequencies to transmit data in the same slot, or can be configured so that even if they use the same frequency, they are spaced apart on the network. Therefore, in addition to the above effects, the communication system of this embodiment can suppress interference within the same network.

(Variation 1)
It is preferable that the communication control unit 10F and the communication control unit 20F control the data communication using at least one of the transmission power, modulation method, and error correction method that enable data to wirelessly reach the communication destination, which is the first communication destination or the second communication destination.

For example, assume that the determination unit 10E and the determination unit 20E have determined the wireless frequency to be used for communication to the first communication destination, which is one hop away. In this case, the communication control unit 10F and the communication control unit 20F control the data communication using a predetermined transmission power, modulation method, and error correction method that allows data to reach the first communication destination wirelessly.

Also, for example, assume that the determination unit 10E and the determination unit 20E have determined the radio frequency to be used for communication to the second communication destination, which is two or more hops away. In this case, the communication control unit 10F and the communication control unit 20F control the data communication by changing at least one of the predetermined transmission power, modulation method, and error correction method so that the second communication destination, which is two or more hops away, can be reached.

This control by communication control unit 10F and communication control unit 20F makes it possible to transmit data to the communication destination with a higher probability and without errors.

(Variation 2)
When the communication control unit 10F and the communication control unit 20F control wireless data communication at a frequency used for data communication to a second communication destination, it is preferable to control the transmission of transmission data at a time other than a predetermined time within the current slot.

The communication control unit 10F and the communication control unit 20F start data transmission at a predetermined time within one slot. For example, assume that the time length of one slot is 100 milliseconds. In this case, it is predetermined that data transmission will start within one slot, for example, 30 milliseconds from the beginning of the slot.

Therefore, when communication control unit 10F and communication control unit 20F control wireless data communication at a frequency used for data communication to a second communication destination that is another communication device two or more hops away, they control the transmission of transmission data at a timing earlier than a predetermined time within the transmission slot. For example, when communication control unit 10F and communication control unit 20F control wireless data communication at a frequency used for data communication to a second communication destination that is another communication device two or more hops away, they start data transmission, for example, 10 milliseconds from the beginning of the slot, which is earlier than a predetermined time within one slot (for example, 30 milliseconds from the beginning of the slot).

By communication control unit 10F and communication control unit 20F controlling the transmission of transmission data at a timing earlier than a predetermined time within the transmission slot, transmission data that is directly transmitted to another communication device that is two or more hops away and has a greater number of hops can be transmitted with higher priority than transmission data that is directly transmitted to another communication device that is one hop away. This allows communication control unit 10F and communication control unit 20F to transmit transmission data in the opposite direction to the communication rule direction with a higher probability.

Second Embodiment
In a second embodiment, a configuration is described that includes a node that is connected to two or more other nodes, and a concentrator may be connected to two or more nodes.

Fig. 12 is a diagram showing a configuration example of a communication system 1B of the second embodiment. As shown in Fig. 12, the communication system 1B of the present embodiment includes a concentrator 200-2, a plurality of nodes 100-2 ₁ to 100-2 ₅ , nodes 100-2 _a to 100-2 _d , and a network 300. Since the nodes 100-2 ₁ to 100-2 ₅ and the nodes 100-2 _a to 100-2 _d have the same configuration, they are simply referred to as node 100-2 when there is no need to distinguish them. The concentrator 200-2 is similar to the concentrator 200 of the above embodiment, except that it is connected to node 100-2 _{1 instead of node 100 1 .}

12, node _100-22 is connected to node _100-23 and node _100-2a . Also, node _100-24 is connected to node _100-25 , node _100-2c , and node _100-2d . In this manner, communication system 1B of this embodiment includes node _100-22 and node _100-24 which are connected to two or more other nodes 100-2.

FIG. 13 is a block diagram showing an example of the configuration of a node 100-2 in the second embodiment. As shown in FIG. 13, the node 100-2 includes a storage unit 10A, a communication unit 10B, an application 10D, a determination unit 10E, and a communication control unit 12F.

Node 100-2 is similar to node 100 in the above embodiment, except that it has a communication control unit 12F instead of communication control unit 10F.

The function of the determination unit 10E is the same as in the above embodiment. Therefore, for example, the same slot and frequency may be determined for the node 100-2 ₅ , the node 100-2 _c , and the node 100-2 _d that have the same first hop count.

Therefore, in this embodiment, the communication control unit 12F controls wireless communication at a determined frequency at a determined timing so that data communication is performed at different times with other communication devices that have the same first hop count.

In detail, when there is another node 100-2 with the same first hop count, the communication control unit 12F adjusts the timing of data generation or transmission between the other node 100-2 and the other node 100-2 so that multiple nodes 100-2 do not transmit data at the same timing. Note that such adjustment may be performed by the application 10D. The following describes an example in which the communication control unit 12F performs such adjustment.

12, for example, node _100-23 and node _100-2a have the same number of hops and therefore have the same transmission slot. To prevent these two nodes 100-2 from transmitting data at the same time, the times or time periods during which data can be transmitted are separated in advance.

For example, the communication control unit 12F determines whether or not there is another node 100-2 with the same first hop count, based on information obtained when connecting to the wireless multi-hop network. If there is another node 100-2 with the same first hop count, the communication control unit 12F controls communication so that data communication is performed with the other node 100-2 with the same hop count at different times. For example, the communication control unit 12F controls data communication to be performed at a pre-specified time or time period different from that of the other node 100-2.

The time or time period may be specified by any method, but for example, a method using absolute time and a method using a slot number or slot frame number that is managed to monotonically increase over time can be applied.

The communication control unit 12F may control data communication at a time or time period different from that of other nodes 100-2 according to a predetermined rule (time determination rule). This rule is, for example, a rule for calculating the time or time period when data can be transmitted from the identification information, interface address, and network address of node 100-2 assigned to node 100-2. For example, the communication control unit 12F may control so that data can be transmitted at 10 minutes past the hour when the remainder of dividing the identification information of node 100-2 by 60 is 10, and so that data can be transmitted at 35 minutes past the hour when the remainder of dividing the identification information of node 100-2 by 60 is 35.

In this way, in the second embodiment, interference within the network can be suppressed even when the network includes a node that is connected to two or more other nodes.

Third Embodiment
In the third embodiment, an example in which a plurality of communication paths are configured between communication devices (concentrators, nodes) will be described.

Fig. 14 is a diagram showing an example of the configuration of a communication system 1C of the third embodiment. As shown in Fig. 14, the communication system 1C of the present embodiment includes a concentrator 200-3, a plurality of nodes 100-3 ₁ to 100-3 ₅ , and a network 300. Since the nodes 100-3 ₁ to 100-2 ₅ have the same configuration, they will be simply referred to as node 100-3 when there is no need to distinguish between them.

As shown in FIG. 14, in this embodiment, the concentrator 200-3 and the node 100-3 configure a wireless multi-hop network so that they are connected by two communication paths. That is, in this embodiment, the concentrator 200-3 and the node 100-3 have two communication paths using two communication units. One communication path is communication path PA consisting of communication unit 20B of the concentrator 200-3 and communication unit 10B of each node 100-3. The other is communication path PB consisting of communication unit 23G (described later) of the concentrator 200-3 and communication unit 13G (described later) of each node 100-3.

In this embodiment, frequencies in different ranges are assigned to the two communication paths. For example, of the multiple available frequencies, frequencies with channel numbers in the first half are assigned to communication path PA, and of the available frequencies, frequencies with channel numbers in the second half are assigned to communication path PB. The method of frequency assignment is not limited to this. For example, frequencies with even and odd channel numbers may be assigned to communication path PA and communication path PB, respectively.

Within the allocated frequency range, the frequency to be used by each node 100-3 is determined in a manner similar to that of the above embodiment.

Fig. 15 is a block diagram showing an example of the functional configuration of the concentrator 200-3 of the third embodiment. As shown in Fig. 15, the concentrator 200-3 includes a memory unit 20A, a communication unit 20B, a communication unit 20C, a communication unit 23G, a communication control unit 23F, a determination unit 20E, and an application 20D.

The concentrator 200-3 of the third embodiment is similar to the concentrator 200 of the first embodiment, except that it further includes a communication unit 23G and a communication control unit 23F instead of the communication control unit 20F.

Similar to communication unit 20B, communication unit 23G communicates with another node 100-3 in the wireless multi-hop network. As described above, communication unit 20B is used in communication path PA, and communication unit 23G is used in communication path PB.

In this embodiment, the determination unit 20E determines the frequency to be used within the range of the allocated frequencies for each of the two communication paths PA and PB. For example, for communication path PA, the determination unit 20E determines the frequency using a procedure similar to that of the above embodiment, with the number of frequencies allocated to communication path PA set to C. Similarly, for communication path PB, the determination unit 20E determines the frequency using a procedure similar to that of the above embodiment, with the number of frequencies allocated to communication path PB set to C.

The communication control unit 23F controls communication using the communication unit 23G in addition to the communication units 20B and 20C.

Fig. 16 is a block diagram showing an example of the configuration of a node 100-3 in the third embodiment. As shown in Fig. 16, the node 100-3 includes a storage unit 10A, a communication unit 10B, an application 10D, a determination unit 10E, a communication control unit 13F, and a communication unit 13G.

The node 100-3 of the third embodiment is similar to the node 100 of the first embodiment described above, except that it has a communication control unit 13F instead of the communication control unit 10F, and further has a communication unit 13G.

Similar to communication unit 10B, communication unit 13G communicates with other nodes 100-3 or concentrator 200-3 in the wireless multi-hop network. As described above, communication unit 10B is used in communication path PA, and communication unit 13G is used in communication path PB.

The determination unit 10E determines the frequency to be used within the range of the allocated frequencies for each of the two communication paths PA and PB. For example, for communication path PA, the determination unit 10E determines the frequency by a procedure similar to that of the above embodiment, with the number of frequencies allocated to communication path PA set to C. Similarly, for communication path PB, the determination unit 10E determines the frequency by a procedure similar to that of the above embodiment, with the number of frequencies allocated to communication path PB set to C.

The communication control unit 13F controls communication using the communication unit 13G in addition to the communication unit 10B.

In this embodiment, different frequencies are used in this way, and communication control is performed as in the first embodiment. Note that the concentrator 200-3 and the node 100-3 may have three or more communication paths. The concentrator 200-3 and the node 100-3 may be provided with a number of communication units that matches the number of communication paths.

In this way, in the third embodiment, interference within the network can be suppressed even in a configuration with multiple communication paths between devices.

Next, the hardware configuration of the communication device according to the first to third embodiments will be described with reference to FIG. 17. FIG. 17 is an explanatory diagram showing an example of the hardware configuration of the communication device according to the first to third embodiments.

The communication device according to the first to third embodiments includes a control device such as a CPU 51, a storage device such as a ROM (Read Only Memory) 52 and a RAM 53, a communication I/F 54 that connects to a network and communicates, and a bus 61 that connects each part.

The programs executed by the communication devices according to the first to third embodiments are provided pre-installed in the ROM 52 etc.

The programs executed by the communication devices according to the first to third embodiments may be configured to be provided as a computer program product by being recorded in an installable or executable format on a computer-readable recording medium such as a CD-ROM (Compact Disk Read Only Memory), a flexible disk (FD), a CD-R (Compact Disk Recordable), or a DVD (Digital Versatile Disk).

Furthermore, the programs executed by the communication devices according to the first to third embodiments may be configured to be stored on a computer connected to a network such as the Internet and provided by being downloaded via the network. Also, the programs executed by the communication devices according to the first to third embodiments may be configured to be provided or distributed via a network such as the Internet.

The programs executed by the communication devices according to the first to third embodiments can cause a computer to function as each part of the communication device described above. In this computer, the CPU 51 can read the programs from a computer-readable storage medium onto the main storage device and execute them.

Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are included in the scope of the invention and its equivalents described in the claims.

100, 100-2, 100-3 Node 200, 200-3 Concentrator 10A, 20A Memory unit 10B, 13G, 20B, 20C, 23G Communication unit 10D, 20D Application 10E, 20E Determination unit 10F, 12F, 13F, 20F, 23F Communication control unit

Claims (16)

a determination unit that determines a timing of data communication by time division multiplexing and a radio frequency to be used for the data communication based on a predetermined determination rule common to a plurality of communication devices, the decision rule using a first hop number from a specific communication device among a plurality of communication devices included in a time division multiplexing communication system;
a communication control unit that controls the data communication by radio at the determined frequency at the determined timing;
Equipped with
The determination unit is
If a first condition is satisfied, a radio frequency to be used for the data communication to a first communication destination one hop away is determined based on the determination rule using the first hop count;
If a second condition is satisfied, a wireless frequency to be used for the data communication to the second communication destination is determined based on the determination rule using the first hop count and a second hop count from the specific communication device to a second communication destination that is two or more hops away.
Communication device. The determination unit is
determining the timing of the data communication by allocating, to each of the plurality of slots, any one of a transmission slot used for data transmission, a reception slot used for data reception, and a sleep slot in which no data transmission or reception is performed, based on the decision rule using the first hop number and a slot number, which is the number of a plurality of slots that are included in a slot frame that is a unit of scheduling and that represents the timing of the data communication;
When the first condition is satisfied, for the current slot, based on the decision rule using the first hop count and a channel number that is the number of a plurality of available frequencies, determine one of the plurality of frequencies as a frequency to be used for the data communication to the first communication destination;
If the second condition is satisfied, for the current slot, based on the decision rule using the first hop count, the second hop count, and the number of channels, determine one of the plurality of frequencies as a frequency to be used for the data communication to the second communication destination.
The communication device according to claim 1 . The determination unit is
calculating the second number of hops based on the number of slots;
The communication device according to claim 2 . The decision rule is:
A rule indicating a communication direction is an upstream direction for communicating data from a child node to a parent node or a downstream direction for communicating data from a parent node to a child node,
The determination unit is
When the transmission slot is assigned to the current slot, and the data to be communicated satisfies the first condition that the data is transmission data to be transmitted in the direction of the communication rule, a radio frequency to be used for the data communication to the first communication destination is determined for the current slot based on the determination rule;
when the transmission slot is assigned to the current slot and the second condition is satisfied that the data to be communicated is transmission data to be transmitted in a direction opposite to the communication rule direction, determining a radio frequency to be used for the data communication to the second communication destination for the current slot based on the determination rule;
The communication device according to claim 2 . The determination unit is
when the transmission slot is assigned to the current slot, data to be communicated is transmission data to be transmitted in the direction of the communication rule or in a direction opposite to the direction of the communication rule, and the first condition is satisfied that the data to be communicated has not yet been transmitted, determining a radio frequency to be used for the data communication to the first communication destination for the current slot based on the determination rule;
determining a wireless frequency to be used for the data communication to the second communication destination for the current slot based on the determination rule when the second condition is satisfied, in which the transmission slot is assigned to the current slot, the data of the communication target is transmission data to be transmitted in the reverse direction, and the data of the communication target has been transmitted at the frequency determined when the first condition is satisfied;
The communication device according to claim 4. The determination unit is
when the transmission slot is assigned to the current slot, the data to be communicated is transmission data to be transmitted in the reverse direction, and the second communication destination satisfies the second condition that the second communication destination is not currently communicating data, determining a radio frequency to be used for the data communication to the second communication destination for the current slot based on the determination rule;
The communication device according to claim 4. The communication control unit
Delete the transmitted data from the storage unit;
The communication device according to claim 1 . The communication control unit
controlling the data communication using at least one of a transmission power, a modulation method, and an error correction method that enables data to reach a communication destination, which is the first communication destination or the second communication destination, by wireless;
The communication device according to claim 1 . The communication control unit
When controlling the data communication by radio using a frequency used for the data communication to the second communication destination, controlling transmission of the transmission data at a time different from a predetermined time within the current slot.
The communication device according to claim 2 . forming a multi-hop network with a plurality of the communication devices such that one or less of the communication devices among the plurality of the communication devices is a parent node;
The communication device according to claim 1 . forming a multi-hop network with a plurality of the communication devices such that one or less of the communication devices among the plurality of the communication devices are child nodes;
The communication device according to claim 1 . The communication control unit
controlling wireless communication at the determined frequency at the determined timing such that the data communication is performed at different times between the communication device and another communication device having the same first hop number;
The communication device according to claim 1 . The plurality of communication devices are connected to each other by a plurality of communication paths,
The plurality of communication paths are assigned frequencies in different ranges,
the determination unit determines, for each of the plurality of communication paths, a frequency to be used for the data communication from among frequencies included in an assigned frequency range.
The communication device according to claim 1 . A communication program for causing a computer to execute the program,
a determination step of determining a timing of data communication by time division multiplexing and a radio frequency to be used for the data communication based on a predetermined determination rule common to a plurality of communication devices, the decision rule using a first hop number from a specific communication device among a plurality of communication devices included in the time division multiplexing communication system;
a communication control step of controlling the data communication by radio at the determined frequency at the determined timing;
Including,
The determining step includes:
If a first condition is satisfied, a radio frequency to be used for the data communication to a first communication destination one hop away is determined based on the determination rule using the first hop count;
If a second condition is satisfied, a wireless frequency to be used for the data communication to the second communication destination is determined based on the determination rule using the first hop count and a second hop count from the specific communication device to a second communication destination that is two or more hops away.
Communications program. A communication system including a plurality of communication devices,
Each of the plurality of communication devices
a determination unit that determines a timing of data communication by time division multiplexing and a radio frequency to be used for the data communication based on a predetermined determination rule common to a plurality of communication devices, the decision rule using a first hop number from a specific communication device among a plurality of communication devices included in a time division multiplexing communication system;
a communication control unit that controls the data communication by radio at the determined frequency at the determined timing;
Equipped with
The determination unit is
If a first condition is satisfied, a radio frequency to be used for the data communication to a first communication destination one hop away is determined based on the determination rule using the first hop count;
If a second condition is satisfied, a wireless frequency to be used for the data communication to the second communication destination is determined based on the determination rule using the first hop count and a second hop count from the specific communication device to a second communication destination that is two or more hops away.
Communications system. 1. A communication method performed in a communication device, comprising:
a determination step of determining a timing of data communication by time division multiplexing and a radio frequency to be used for the data communication based on a predetermined determination rule common to a plurality of communication devices, the decision rule using a first hop number from a specific communication device among a plurality of communication devices included in the time division multiplexing communication system;
a communication control step of controlling the data communication by radio at the determined frequency at the determined timing;
Including,
The determining step includes:
If a first condition is satisfied, a radio frequency to be used for the data communication to a first communication destination one hop away is determined based on the determination rule using the first hop count;
If a second condition is satisfied, a wireless frequency to be used for the data communication to the second communication destination is determined based on the determination rule using the first hop count and a second hop count from the specific communication device to a second communication destination that is two or more hops away.
Communication method.

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