JP2018157489A - Radio communication control program, radio communication apparatus, and radio communication control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the time required for starting a communication using a new network in a radio communication network in a multi-hop communication in which the radio communication is carried out while changing the channel used.SOLUTION: The radio communication apparatus is configured to carry out a series of processing including: carrying out a radio communication while changing the communication channel used; storing the changing order of the communication channel used in a first network in a storage part; and transmitting, when the radio communication is carried out by using the second network in which the radio communication is carried out according to the changing order of the communication channels, a piece of information with which the changing order of the communication channels used in the second network can be identified by using the timing at which a predetermined communication channel is used according to the changing order of the communication channels used in the first network.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a wireless communication control program, a wireless communication apparatus, and a wireless communication control method.

  One type of wireless communication network is an ad hoc network in which wireless nodes communicate with each other. A network in which wireless nodes communicate with each other is also called an autonomous distributed network. In addition, as one of ad hoc network communication methods, there is multi-hop communication in which a node relays a radio signal from another node.

  In a wireless communication network, for example, in order to avoid data collision and improve communication efficiency, the operation timing between nodes in the network may be the same. The fact that the operation timing between nodes is the same is referred to as being synchronized, for example. Also, making the operation timing between nodes the same is referred to as synchronizing, for example. Synchronized wireless communication networks are called, for example, a synchronous network and a synchronous network.

  In the synchronization network, for example, a synchronization signal is periodically transmitted by a node serving as a synchronization base point. The synchronization signal is transmitted by multicast or broadcast, for example. For example, the synchronization signal includes information used for synchronization. Hereinafter, a node serving as a synchronization base point is simply referred to as a base point node. For example, the base node is a node that operates as a gateway in Zigbee.

  The node that has received the synchronization signal synchronizes the operation timing with the base node using information included in the synchronization signal. In a multi-hop communication network, a node that has received a synchronization signal from a base node periodically transmits the synchronization signal in the same manner as the base node. Accordingly, a node existing outside the communicable range of the base node can also receive the synchronization signal, and can be synchronized with the base node.

  On the other hand, channel hopping is one of the methods for avoiding the collision of used frequencies between networks. Channel hopping is a technique for performing communication while changing a channel used in wireless communication every predetermined time. Employing channel hopping can prevent a specific frequency band from being occupied.

  In channel hopping, the frequency used is changed every time a predetermined time elapses, so that even when noise occurs at one frequency, packet loss due to noise can be corrected by data transmitted at another frequency. . Therefore, a wireless communication network that employs channel hopping has high fault tolerance. Moreover, since the transmission frequency changes in a specific pattern, the confidentiality of communication is high. Therefore, channel hopping is often employed in many-to-many wireless communication networks such as ad hoc networks.

  In a network in which channel hopping is adopted, a node synchronized with a base node performs channel transition in the same channel transition order as that of the base node at the same channel transition timing as that of the base node. Information for specifying the channel transition order of the base node is acquired from information included in the synchronization signal, for example. The synchronization signal also includes information for synchronizing with the base node.

  In channel hopping, the channel transition order is obtained by a predetermined algorithm by each node. Hereinafter, the channel transition order is referred to as a hopping pattern. In channel hopping, the hopping pattern is different for each network in order to avoid interference between networks. Therefore, the hopping pattern is different between the synchronized network and the adjacent network. In addition, the hopping pattern is often different for each frame, which is a unit time, for example.

  Note that, for the transmission of the synchronization signal, for example, wireless communication standards such as IEEE 802.15 series and BLUETOOTH (registered trademark) stipulate that the channel with the smallest number among usable channels is used. That is, in a network that employs channel hopping, the hopping pattern is different for each network, but the channel used for transmission of the synchronization signal is common. The channel used for transmitting the synchronization signal is hereinafter referred to as a scan channel.

  For example, in a synchronous ad hoc network, when a relay node becomes incapable of communication due to a failure of a relay node or power depletion, a node that is located farther from the base node than the relay node is Even if the synchronization signal can be continuously received, the reception quality of the synchronization signal may deteriorate. In addition, for example, when a new base node is installed at a distance closer to the base node of the synchronization destination network, it is newly installed than the reception quality of the synchronization signal from the base point node of the network being synchronized In some cases, the reception quality of the synchronization signal from the base node is better.

  In such a case, it is desirable to change the synchronization destination network to an adjacent network including a node that transmits a signal with better reception quality.

Special table 2014-504078 gazette

  However, in order to change the synchronization destination network in a multi-hop communication wireless communication network in which channel hopping is adopted, it takes time until the period in which the scan channel is used in the synchronized network and the adjacent network overlap. May be required.

  As a result, a multi-hop wireless communication network employing channel hopping has a problem that it takes time to complete the change of the synchronized network.

  The present invention relates to a wireless communication control program, a wireless communication apparatus, and a wireless communication control program capable of reducing the time required to start communication using a new network in a wireless communication network for multi-hop communication in which wireless communication is performed while changing a use channel. An object of the present invention is to provide a wireless communication control method.

One aspect of the present invention is a wireless communication control program executed by a wireless communication apparatus. The wireless communication control program causes the wireless communication device to perform wireless communication while changing the communication channel to be used. The wireless communication control program causes the wireless communication apparatus to store the transition order of communication channels used in the first network. Further, the wireless communication control program, when wireless communication is performed using the second network in which wireless communication is performed according to the communication channel transition order, is performed on the wireless communication device, the communication channel transition order used in the first network. According to the above, at a timing at which a predetermined communication channel is used, information that can specify the transition order of communication channels used in the second network is transmitted using the predetermined communication channel.

  According to the disclosed wireless communication control program, wireless communication device, and wireless communication control method, in the wireless communication network of multi-hop communication in which wireless communication is performed while changing the use channel, until the start of communication using a new network Can be shortened.

FIG. 1 is a diagram illustrating an example of a system configuration of a wireless communication network system according to the first embodiment. FIG. 2 shows the channel transition between the node # 1 and the node # 2 until the node # 2 receives the synchronization signal from the NW # 2 and starts synchronization with the NW # 2 in the example shown in FIG. It is a figure which shows an example. FIG. 3 is a diagram illustrating an example of a system configuration of a wireless communication network in a state where the node # 2 has completed synchronization with the NW # 2. FIG. 4 is a diagram illustrating an example of channel transition of the node # 1 to the node # 4 following the example illustrated in FIG. FIG. 5 is a diagram illustrating an example of a system configuration of the wireless communication network system in a state where the synchronization of the node # 3 and the node # 4 is also completed with the NW # 2. FIG. 6 is a diagram illustrating an example of a hardware configuration of a node. FIG. 7 is a diagram illustrating an example of a functional configuration of a node. FIG. 8 is a diagram illustrating an example of information for specifying a hopping pattern included in the payload of the beacon packet in the wireless communication network according to the first embodiment. FIG. 9A is an example of a flowchart of processing of a node when a synchronization signal of a network different from the currently synchronized network is received. FIG. 9B is an example of a flowchart of node processing when a synchronization signal of a network different from the currently synchronized network is received. FIG. 10 is an example of a flowchart of node processing when an abnormality in the network being synchronized is detected. FIG. 11 is a diagram illustrating an example of channel transition between the node # 1 and the node # 2 when an abnormality of the network being synchronized is detected. FIG. 12 is a diagram illustrating an example of channel transition between the node # 1 and the node # 2 when an abnormality of the network being synchronized is detected. FIG. 13 is a diagram illustrating an example of channel transition of the node # 1 to the node # 4 following the example illustrated in FIG. 11 or FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The configuration of the following embodiment is an exemplification, and the present invention is not limited to the configuration of the embodiment.

<First Embodiment>
FIG. 1 is a diagram illustrating an example of a system configuration of a wireless communication network system 100 according to the first embodiment. The wireless communication network system 100 includes, for example, a network # 1 and a network # 2. The network # 1 and the network # 2 are networks managed by the same management organization, for example. Network # 1 and network # 2 each include a plurality of nodes 1 that perform wireless communication. When the nodes are not particularly distinguished, they are expressed as node 1. Hereinafter, the network may be referred to as NW. The node 1 is an example of a “wireless communication device”. Network # 1 is an example of a “first network”. Network # 2 is an example of a “second network”.

  The wireless communication network system 100 is, for example, a wireless LAN network such as Zigbee or IEEE802.11a / 11b / 11g / 11n, or a BLEUTOOTH (registered trademark) network system. However, the wireless communication network system 100 is not limited to these networks. In the first embodiment, it is assumed that the wireless communication network system 100 is a Zigbee network. The synchronization signal in the Zigbee network is a beacon signal. A beacon signal is an example of a “synchronization signal”. The channel through which the beacon signal is transmitted is an example of a scan channel. The scan channel is an example of “predetermined communication channel” and “channel used for transmission of synchronization signal”.

  The node 1 is, for example, a node that includes a sensor that measures used power. In this case, the wireless communication network system 100 is, for example, a power metering system that collects data of power used measured by the node 1.

  NW # 1 and NW # 2 are networks in which multihop communication is performed. In NW # 1 and NW # 2, gateway (GW) # 1 and GW # 2 are base nodes, respectively. Each node 1 included in NW # 1 and NW # 2 performs channel hopping. Channel hopping is an example of performing “wireless communication while changing the communication channel to be used”.

  In the example illustrated in FIG. 1, a case where a plurality of nodes 1 that perform NW # 1 relay are in a communication disabled state is illustrated. Node 1 falls into a communication disabled state, for example, when a hardware failure of node 1 occurs or when power of node 1 is lost. Further, when the node 1 has been removed, the node 1 and other nodes in the NW # 1 are in a communication disabled state.

  Node # 2, node # 3, and node # 4 are nodes that communicate in synchronization with GW # 1 of NW # 1. However, since the plurality of nodes 1 that existed on the GW # 1 side have fallen into a communication disabled state, the communication quality of the signal from the GW # 1 is degraded in the node # 2, the node # 3, and the node # 4. ing.

  The signal from GW # 1 is, for example, a synchronization signal, an acknowledgment response, or the like. The communication quality of the signal from GW # 1 is represented by the cost calculated based on, for example, the received radio wave intensity, the number of hops to GW # 1, and the like. For example, a signal from GW # 1 reaches node # 2 via node # 3. In node # 3, after the occurrence of node 1 in the communication disabled state, the signal from GW # 1 is received without being relayed by another node 1, so the reception strength of the signal from GW # 1 decreases. Communication quality is degraded.

  In the node # 2, for example, the signal from the GW # 1 is received by the relay by the node # 3. Therefore, when the signal is amplified at the time of the relay by the node # 3, the node in the communication disabled state The reception strength of the signal from GW # 1 does not decrease before and after the occurrence of 1. However, since the communication quality has deteriorated after the occurrence of the node 1 in the communication disabled state at the node # 3, the cost indicating the communication quality is the same as that after the occurrence of the node 1 in the communication disabled state at the node # 2. Suppose that it is calculated | required using the algorithm which shows that communication quality falls.

  For example, the node # 2 is located within the reach of a signal transmitted from the node # 1 synchronized with the NW # 2. Therefore, node # 2 can receive a synchronization signal transmitted from node # 1. On the other hand, the node # 3 and the node # 4 are not located within the reachable range of the signal of any node synchronized with the NW # 2, and cannot receive the synchronization signal including the information of the NW # 2.

  In order to change the network to be synchronized, it is necessary to receive the synchronization signal of the network to be changed. Accordingly, the node # 2 can receive the synchronization signal including the information of the NW # 2 transmitted from the node # 1, and if the communication quality of the signal from the NW # 2 is better, the node # 2 You can change the synchronization destination. Changing the synchronization destination network is an example of changing the network to be used.

  The node # 3 and the node # 4 are located within the signal reachable range of the node # 2, and the node # 2 can receive the NW # 2 synchronization signal by transmitting the NW # 2 synchronization signal. . The synchronization signal of the adjacent network can be received if the node uses the scan channel at the same timing as the adjacent network.

  However, since the hopping pattern is different between the synchronized network and the adjacent network, it may take time until the period during which the scan channel is used is overlapped between the synchronized network and the adjacent network.

  For example, in the example illustrated in FIG. 1, the node # 3 and the node # 4 change channels according to the hopping pattern of NW # 1. Since node # 2 is synchronized with NW # 2, the channel is changed according to the hopping pattern of NW # 2. Therefore, the node # 3 and the node # 4 cannot receive the synchronization signal including the information on the NW # 2 until the timings at which the scan channels are used match between the NW # 1 and the NW # 2. The hopping pattern is an example of “transition order of communication channels used in the network”.

  In the first embodiment, for example, when the synchronization destination is changed to NW # 2, the node # 2 transmits a synchronization signal including the information of NW # 2 at a timing at which the scan channel is used according to the hopping pattern of NW # 1. To do. The synchronization signal includes, for example, information for obtaining synchronization and information capable of specifying a hopping pattern. Changing the synchronization destination to NW # 2 is an example of “when wireless communication is performed using the second network”. The information that can specify the hopping pattern is an example of “information that can specify the transition order of communication channels used in the second network”.

  Therefore, according to the hopping pattern of NW # 1, node # 2 transmits a synchronization signal including NW # 2 information at the use timing of the scan channel, so that node # 3 and node # 4 have hopping patterns of NW # 1. The synchronization signal including the information of NW # 2 can be received while remaining in compliance. The node # 3 and the node # 4 can quickly synchronize with the NW # 2 without waiting for the scan channel timing to overlap between the NW # 1 and the NW # 2.

  FIG. 2 shows the channel transition between the node # 1 and the node # 2 until the node # 2 receives the synchronization signal from the NW # 2 and starts synchronization with the NW # 2 in the example shown in FIG. It is a figure which shows an example. In a synchronous network, the start points of time units called frames are synchronized between nodes. For example, in Zigbee, a frame is also called a super frame, and the frame length is set in the range of several tens of milliseconds to 500 milliseconds.

  The frame is further divided into a predetermined number of subframes. A subframe is also called a time slot. In channel hopping, the channel changes every subframe. In the example shown in FIG. 2, there are five channels # 1 to # 5, and for convenience, the frame is divided into five subframes. However, the number of frame divisions does not depend on the number of channels used. Channel # 1 is used as a scan channel.

  In one frame, some or all of the time slots other than the time slots allocated to the scan channel are used for transmitting data, for example. That is, the hopping pattern is information indicating transmission timing for transmitting a synchronization signal and transmission timing for transmitting data in one frame in each network.

  The information included in the synchronization signal and the information that can specify the hopping pattern included in the synchronization signal are examples of “advertised data in the network”. The frame is an example of “unit time”. In addition, a time slot allocated to a scan channel in one frame is an example of “timing to transmit“ advertised data in unit time ””. In addition, a time slot used for data transmission in a time slot other than the time slot assigned to the scan channel in one frame is an example of “timing for transmitting“ data ”in“ unit time ”.

  The order of channel transition in one frame differs between networks. In the example shown in FIG. 2, the order in which the channels transition varies from frame to frame. The scan channel is assumed to be channel # 1 for both NW # 1 and NW # 2.

  In FIG. 2, for the sake of convenience, the start points of the frames of the node # 1 and the node # 2 are displayed as being synchronized. Actually, since the node # 1 and the node # 2 are synchronized with different networks, the frame start points of the node # 1 and the node # 2 are not always synchronized.

  In the example shown in FIG. 2, in frames # 0 to # 2, node # 1 performs channel hopping according to the hopping pattern of NW # 2. Node # 2 performs channel hopping according to the hopping pattern of NW # 1. Therefore, while the node # 1 is transmitting the synchronization signal on the scan channel (channel # 1), the node # 2 is using another channel and may receive the synchronization signal transmitted from the node # 1. Can not.

  In the example shown in FIG. 2, in frame # 3, the timings at which the scan channels are used at node # 1 and node # 2 match. Thereby, the node # 2 can receive the synchronization signal including the information of the NW # 2 transmitted from the node # 1, and can know the existence of the NW # 2.

  In the example shown in FIG. 2, in the frame # 3, the timings at which the scan channels are used at the node # 1 and the node # 2 are the same. However, in practice, it is unclear when the timing at which the scan channel is used matches between node # 1 and node # 2. In the example illustrated in FIG. 2, the node # 2 also receives a synchronization signal including NW # 1 information in the scan channel (channel # 1).

When the node # 2 receives the synchronization signal including the information of NW # 2 from the node # 1, it determines that the communication quality of NW # 2 is better than the communication quality of NW # 1, and sets the synchronization destination to NW # Determine to change to 2. Thereafter, the node # 2 performs a synchronization preparation process for synchronizing with the NW # 2. In the synchronization preparation process, for example, a hopping pattern is generated from information acquired from the synchronization signal, and the start timing of a new hopping pattern is adjusted. In FIG.
Node # 2 starts channel hopping according to the hopping pattern of NW # 2 from the start point of frame # 5, and starts synchronization with NW # 2.

  In the first embodiment, the start of synchronization with a new NW is set as the start point of frame # n + 2 two frames after frame #n where the change of the synchronization destination to the NW is determined. This is a scan channel in the last subframe in the frame, and a new NW synchronization signal may be received. In this case, it is difficult to synchronize from the immediately following frame to the new NW. Because there is. However, the start of synchronization with a new NW is not limited to the start point of the frame two frames after the frame for which the change of the synchronization destination to the NW has been determined.

  FIG. 3 is a diagram illustrating an example of a system configuration of the wireless communication network system 100 in a state where the node # 2 has been synchronized with the NW # 2. The example shown in FIG. 3 is the state of the wireless communication network system 100 at the time of frame # 5 in the example shown in FIG.

  Since the node # 2 receives the synchronization signal including the information on the NW # 2 from the node # 1 and changes the synchronization destination to the NW # 2, the node # 2 can perform communication with better communication quality. On the other hand, the node # 3 and the node # 4 perform channel hopping according to the hopping pattern of NW # 1, and perform communication with a low communication quality. In this specification, synchronizing with a new network is also expressed as joining or joining a new network. A new synchronization destination network may be referred to as a new NW. Further, the NW that has been synchronized until immediately before may be referred to as the previous NW.

  In the first embodiment, the node # 2 synchronizes with the new NW according to the hopping pattern of the new NW, but continues to hold the hopping pattern of the previous NW for a predetermined period. When the scan channel is used in the hopping pattern of the previous NW # 1, the node # 2 transmits synchronization information including information on the new NW # 2 using the scan channel of the previous NW # 1.

  FIG. 4 is a diagram illustrating an example of channel transition of the node # 1 to the node # 4 following the example illustrated in FIG. Since node # 2 holds the hopping patterns of NW # 1 and NW # 2, channel transition (upper stage) according to the hopping pattern of NW # 2, which is the new NW, and NW #, which is the previous NW A channel transition (lower stage) according to a hopping pattern of 1 is shown.

  Node # 2 starts synchronization with NW # 2 in frame # 5 (FIG. 2). In the next frame # 6, the node # 2 starts determining the timing of transition to the scan channel according to the hopping pattern of NW # 1. For example, in frame # 5 where synchronization with NW # 2 is started, it may not be possible to use the scan channel use timing in the first subframe in the hopping pattern of NW # 1.

  Node # 2 determines the timing of transition to the scan channel according to the hopping pattern of NW # 1 at the start point of the second subframe of frame # 6, transitions to the scan channel, and includes information on NW # 2 Send a sync signal.

  When the node # 3 and the node # 4 transition to the scan channel according to the hopping pattern of the NW # 1 in the frame # 6, the node # 3 and the node # 4 receive the synchronization signal including the information of the NW # 2 transmitted from the node # 2. Thereby, the node # 3 and the node # 4 can know the existence of the NW # 2. Each of the node # 3 and the node # 4 determines a change of the synchronization destination to the NW # 2 with better communication quality, and performs a synchronization preparation process for the NW # 2, for example, from the frame # 8 to the NW # 2 Start syncing.

  Note that, in the frame # 6, the node # 2 transitions to the NW # 1 scan channel according to the NW # 1 hopping pattern, and then transitions to the channel according to the NW # 2 hopping pattern in the next subframe.

  FIG. 5 is a diagram illustrating an example of a system configuration of the wireless communication network system 100 in a state where the nodes # 3 and # 4 are also synchronized with the NW # 2. The example shown in FIG. 5 is the state of the wireless communication network system 100 after frame # 8 in the example shown in FIG.

  Since the node # 3 and the node # 4 have received the synchronization signal including the information of the NW # 2 from the node # 2 and changed the synchronization destination to the NW # 2, the communication is performed through the NW # 2 with better communication quality. It can be carried out. As a result, when a plurality of nodes 1 to be relayed fall into a communication disabled state, all nodes # 2 to # 4 that can communicate with better communication quality when synchronized with NW # 2 than NW # 1 are all connected to NW # 2. You can join and communicate. In the first embodiment, the node # 2 to node # 4 can change the synchronization destination to NW # 2 within a time period of several frames after the plurality of relayed nodes 1 fall into a communication disabled state.

  In the first embodiment, the node # 3 and the node # 4 perform the same operation as the node # 2. Therefore, for example, even if another node exists downstream of node # 3 (in the direction away from NW # 2), the node downstream of node # 3 can quickly change the synchronization destination to NW # 2. . This is because the node # 3 transmits an NW # 2 synchronization signal on the NW # 1 scan channel according to the hopping pattern of the NW # 1 in the frame immediately after the synchronization with the NW # 2.

<Device configuration>
FIG. 6 is a diagram illustrating an example of the hardware configuration of the node 1. The node 1 is, for example, a dedicated or general-purpose device that includes a sensor and a wireless communication function. The node 1 includes a control unit 101, a memory 102, a radio unit 103, a clock 104, a power feeding unit 105, an antenna 106, and a sensor 107 as hardware components.

  The memory 102 is a semiconductor memory such as a RAM (Random Access Memory), for example. The memory 102 may include a ROM (Read Only Memory). The memory 102 stores various programs and data used by the control unit 101 when executing each program. The memory 102 holds, for example, a channel hopping control program 102P, an OS (Operating System), a driver corresponding to each hardware component, and the like. When the channel hopping control program 102P changes the synchronization destination to the new NW described in FIGS. 1 to 5 to the node 1, the channel hopping control program 102P sends a synchronization signal including information on the new NW on the scan channel according to the hopping pattern of the previous network. It is a program for executing the process to transmit. The channel hopping control program 102P is an example of a “wireless communication control program”. The memory 102 is an example of a “storage unit”.

  The control unit 101 includes, for example, a processor and a memory. The memory included in the control unit 101 is a memory that provides a work area to the processor. The memory included in the control unit 101 is, for example, a RAM whose access speed is higher than that of the memory 102. The processor executes various processes by loading the OS and various application programs held in the memory 102 into the memory in the control unit 101 and executing them. The number of processors included in the control unit 101 is not limited to one, and a plurality of processors may be provided. The control unit 101 is an example of a “control unit”.

  The wireless unit 103 includes a circuit that modulates and demodulates a signal transmitted and received by the antenna 106, and a circuit that converts a baseband signal and an electric signal. In the first embodiment, since the wireless communication network system 100 is a Zigbee network, the wireless unit 103 and the antenna 106 are, for example, IEEE. It corresponds to 802.15.4. However, the wireless unit 103 and the antenna 106 are appropriately adopted according to the wireless communication method employed by the wireless communication network system 100. For example, when the wireless communication network system 100 adopts BLUETOOTH or BLE (Bluetooth Low Energy) as a wireless communication method, the wireless unit 103 and the antenna 106 correspond to BLUETOOTH or BLE.

  A signal received by the antenna 106 and processed by the wireless unit 103 is output to the control unit 101. The radio unit 103 receives a signal from the control unit 101, and the input signal is subjected to a conversion process from a baseband signal to an electric signal and a modulation process to the electric signal, and is output to the antenna 106. The wireless unit 103 is an example of a “wireless communication unit”.

  The clock 104 propagates a clock signal having a predetermined clock frequency to the control unit 101. The control unit 101 performs processing in synchronization with the clock signal from the clock 104. The clock signal of the clock 104 is used, for example, time, time measurement, frame start point measurement, or the like.

  The power supply unit 105 supplies electricity to each hardware component, for example. Although omitted in the figure, the power supply unit 105 and each hardware component are electrically connected. When the node 1 operates with a battery, the power supply unit 105 includes, for example, a button-type, pin-type lithium battery, solar battery, and the like.

  The sensor 107 is a sensor that observes one or more of, for example, temperature, humidity, acceleration, pressure, vibration, magnetism, current, voltage, and the like. For example, the sensor 107 performs an observation when a predetermined cycle or a predetermined event occurs, and outputs the observation result to the control unit 101.

  Note that the hardware configuration of the node 1 illustrated in FIG. 6 is an example and is not limited to the above, and components can be omitted, replaced, or added as appropriate according to the embodiment. For example, the node 1 may include a portable recording medium driving device and execute a program recorded on the portable recording medium. The portable recording medium is, for example, an SD card, a miniSD card, a microSD card, a USB (Universal Serial Bus) flash memory, a CD (Compact Disc), a DVD (Digital Versatile Disc), a Blu-ray (registered trademark) Disc, or a flash. A recording medium such as a memory card.

  FIG. 7 is a diagram illustrating an example of a functional configuration of the node 1. The node 1 includes, as functional components, a transmission unit 11, a reception unit 12, a synchronization packet generation unit 13, a timer 14, a channel transition unit 15, a channel setting unit 16, a synchronization processing unit 17, a first NW synchronization information management table 18A, a first 2NW synchronization information management table 18B and network specific information storage unit 19 are provided.

  The transmission unit 11, the reception unit 12, and the channel setting unit 16 are functional components corresponding to the driver of the wireless unit 103. The transmission unit 11 and the reception unit 12 are interfaces with the wireless unit 103. The channel setting unit 16 sets a use channel for the channel input from the channel transition unit 15.

Synchronization packet generation unit 13, timer 14, channel transition unit 15, channel setting unit 16, synchronization processing unit 17, first NW synchronization information management table 18A, second NW synchronization information management table 18B, network specific information storage unit 19 101 is a functional component achieved by executing the channel hopping control program 102P.

  The timer 14 determines the synchronization timing based on the clock signal generated by the clock 104. The synchronization timing is, for example, the start point of a frame. The timer 14 determines the start point of the subframe based on the clock signal generated by the clock 104. The timer 14 outputs the determined frame start point and subframe start point to the synchronization packet generation unit 13, the channel transition unit 15, and the synchronization processing unit 17.

  The synchronization packet generator 13 generates a synchronization signal and outputs it to the transmitter 11. The synchronization packet generator 13 outputs a synchronization signal at a timing when the scan channel is used. The synchronization packet generation unit 13 determines the timing at which the scan channel is used as the hopping stored in the start point of the subframe input from the timer 14 and the first NW synchronization information management table 18A or the second NW synchronization information management table 18B. Judgment is made based on the pattern. The synchronization packet generation unit 13 reads and acquires the unique information of the network being synchronized from the network unique information storage unit 19 as information to be included in the synchronization signal.

  The channel transition unit 15 receives the notification of the start point of the frame and the start point of the subframe from the timer 14, and according to the hopping pattern stored in the first NW synchronization information management table 18A or the second NW synchronization information management table 18B. The transition destination channel is determined and notified to the channel setting unit 16.

  The synchronization processing unit 17 determines whether the synchronization packet generation unit 13 and the channel transition unit 15 refer to the first NW synchronization information management table 18A or the second NW synchronization information management table 18B.

  The first NW synchronization information management table 18A and the second NW synchronization information management table 18B are stored in a storage area secured in the memory 102, for example. In the first embodiment, the first NW synchronization information management table 18A and the second NW synchronization information management table 18B hold the hopping patterns of the channels of the synchronized NW and the spare NW, respectively. The spare NW is, for example, an NW having the highest communication quality after the synchronized NW in which the node 1 has received the synchronization signal. When a synchronization signal is not received from an NW other than the synchronized NW, the second NW synchronization information management table 18B is empty or not created.

  However, it is not limited to this. It may not be fixed which of the first NW synchronization information management table 18A and the second NW synchronization information management table 18B holds the hopping pattern of the synchronized NW. The synchronization processing unit 17 manages which of the first NW synchronization information management table 18A and the second NW synchronization information management table 18B stores the synchronized NW hopping pattern.

  When the synchronization processing unit 17 receives an input of a synchronization signal including information on a network different from the currently synchronized network from the reception unit 12, the synchronization processing unit 17 performs a process of selecting a network to be synchronized based on the synchronization signal. The process of selecting a network to be synchronized is a process of selecting a network to be synchronized according to a predetermined determination criterion from among the received synchronization signals for a plurality of networks. The criteria for determining the network to be synchronized are, for example, cost values calculated based on the received radio wave intensity of the synchronization signal, the number of hops to the base node, and the like.

  When the network selection process selects a network different from the currently synchronized network, the synchronization processing unit 17 performs a synchronization preparation process to synchronize the node 1 with the selected network.

  The node 1 receives a synchronization signal including information on a network different from the currently synchronized network when, for example, the use timing of the scan channel matches between the currently synchronized network and another network. For example, this is a case where the node 1 performs a network search process.

  The network search process is a process for searching for a network in which the node 1 is present. Specifically, the network search process is a process of detecting a network when the node 1 receives a synchronization signal. The network search process is controlled by the synchronization processing unit 17 in the first embodiment. In the network search process, a scan channel is used. In the network search process, the synchronization processing unit 17 stops using the hopping pattern, and causes the channel transition unit 15 to set the use channel as the scan channel. For example, the used channel remains in the scan channel until a network is detected or for a predetermined time.

  The network search process may be performed by, for example, either a passive scan that waits for reception of a synchronization signal or an active scan that detects a network by transmitting a request signal by itself and receiving a response signal.

  In the network search process, for example, when the node 1 is in an initial state that is not synchronized with any NW, an abnormality of the currently synchronized network is detected, or an instruction to start the network search process is input through the network It is performed when it is done. For example, the synchronization processing unit 17 does not receive information from the base node for a predetermined period, thereby determining an abnormality in the currently synchronized network. Examples of the information from the base node include a beacon packet and an acknowledgment response.

  When the input synchronization signal includes new network information, the synchronization processing unit 17 stores the network specific information included in the input synchronization signal in the network specific information storage unit 19. The new network is a network in which unique information is not held in the network unique information storage unit 19. The network unique information included in the synchronization signal is, for example, network identification information, information used for synchronization, and information used for specifying a hopping pattern.

  In addition, the synchronization processing unit 17 includes the new network unique information included in the synchronization signal when the input synchronization signal includes information on the new network and the communication quality of the new network satisfies a predetermined condition. To generate a hopping pattern. The synchronization processing unit 17 stores the generated new network hopping pattern in the first NW synchronization information management table 18A or the second NW synchronization information management table 18B. Detailed processing will be described later.

  The synchronization processing unit 17 performs the following processing when a new NW different from the synchronized NW is selected as the synchronization destination as a result of the selection processing of the network to be synchronized. In the following description, it is assumed that the hopping pattern of the synchronized NW is stored in the first NW synchronization information management table 18A. It is assumed that the new NW hopping pattern is stored in the second NW synchronization information management table 18B.

In the synchronization preparation process for the new NW, the synchronization processing unit 17 instructs the synchronization packet generation unit 13 and the channel transition unit 15 to refer to the second NW synchronization information management table 18B that holds the hopping pattern of the new NW, The timing of switching the previous table is instructed. The reference table switching timing is, for example, the start point of frame # n + 2 two frames after the current frame #n. However, the timing of switching the reference table is not limited to this. Switching of the table referred to by the synchronization packet generation unit 13 and the channel transition unit 15 means that the hopping pattern is changed. In addition, switching of the table referred to by the synchronization packet generation unit 13 and the channel transition unit 15 means that the synchronization destination is changed to a new network.

  On the other hand, the synchronization processing unit 17 refers to the first NW synchronization information management table 18A and determines the timing at which the scan channel is used according to the hopping pattern of the previous NW. When the synchronization processing unit 17 determines the timing of transition to the scan channel according to the hopping pattern of the previous NW, the synchronization processing unit 17 stores the hopping pattern of the previous NW in the synchronization packet generation unit 13 and the channel transition unit 15 to the first NW synchronization information management table 18A. Direct reference. As a result, the synchronization packet generation unit 13 and the channel transition unit 15 refer to the first NW synchronization information management table 18A, and the use channel of the node 1 is set as the scan channel at the timing when the scan channel is used in the hopping pattern of the previous network. And a synchronization signal is transmitted. However, at this time, the synchronization signal generated by the synchronization packet generation unit 13 includes unique information of the new NW.

  When the synchronization processing unit 17 determines the timing of transition from the scan channel to another channel according to the hopping pattern of the previous NW, the synchronization packet generating unit 13 and the channel transition unit 15 store the hopping pattern of the new NW. Instructs reference to the 2NW synchronization information management table 18B. As a result, the synchronization packet generation unit 13 and the channel transition unit 15 refer to the second NW synchronization information management table 18B, and the used channel is determined according to the hopping pattern of the new NW.

  In the first embodiment, the synchronization processing unit 17 repeatedly executes the transition to the scan channel according to the hopping pattern of the previous NW and transmits the synchronization signal including the unique information of the new NW for a predetermined period or a predetermined number of times. This is because the unique information of the new NW is reliably delivered to the other nodes 1 located on the base node side of the previous NW.

  The synchronization processing unit 17 deletes the hopping pattern of the previous NW when the transition to the scan channel is performed according to the hopping pattern of the previous NW for a predetermined period or a predetermined number of times and transmission of the synchronization signal including the unique information of the new NW is finished. To do. The deletion of the hopping pattern of the previous NW may be performed by deleting the first NW management information synchronization table 18A, or may be performed by making the first NW management information synchronization table 18A empty.

  Thereafter, for example, the hopping pattern of the new NW that has been handled as the second NW synchronization information management table 18B is handled as the first NW synchronization information management table 18A. In this case, the second NW synchronization information management table 18B is empty. The above is the processing of the synchronization processing unit 17 when the synchronization destination is changed from the synchronized NW to a different new NW.

  If the table storing the hopping pattern of the synchronized NW is not fixed to the first NW synchronization information management table 18A, for example, the synchronization processing unit 17 may perform the following processing. The first NW synchronization information management table 18A stores the hopping pattern of the previous NW. When the hopping pattern of the previous NW is deleted, the synchronization processing unit 17 sets the hopping pattern of the newly detected NW to the first NW Stored in the synchronization information management table 18A. Accordingly, the second NW synchronization information management table 18B holds the hopping pattern of the NW being synchronized. It is the first NW synchronization information management table 18A that holds the spare NW hopping pattern. Thereafter, when it is determined that the synchronization destination is changed to an NW different from the synchronized NW, the synchronization processing unit 17 changes the referenced table from the second NW synchronization information management table 18B to the first NW synchronization information management. Switch to table 18A.

  The synchronization processing unit 17 obtains a hopping pattern using a predetermined algorithm and a predetermined parameter. The algorithm for obtaining the hopping pattern is common to all the nodes 1 in the wireless communication network system 100, for example. The hopping pattern is calculated, for example, by assigning a parameter value to an algorithm for obtaining the hopping pattern. For example, by using a known random number generating algorithm as an algorithm for obtaining a hopping pattern, the hopping pattern can be varied for each frame. However, the present invention is not limited to this, and the hopping pattern may be common between frames.

  The parameters for obtaining the hopping pattern are common between the nodes 1 synchronized with the same network, and are different between different networks. As a result, the hopping pattern can be made different between networks. The parameter for obtaining the hopping pattern is one of unique information included in the synchronization signal.

  The network specific information storage unit 19 is stored in a storage area secured in the memory 102, for example. The network unique information storage unit 19 holds network unique information detected by the node 1. Network specific information is included in the synchronization signal. The network unique information includes, for example, network identification information, information for synchronization, information for specifying a hopping pattern, and the like. An example of information for specifying a hopping pattern is a parameter for obtaining a hopping pattern, for example.

  When the node 1 detects a plurality of networks, the network unique information storage unit 19 holds the unique information of the plurality of networks. For example, in the network unique information storage unit 19, the unique information of the currently synchronized network is indicated by a pointer. The pointer is controlled by the synchronization processing unit 17, for example. For example, the synchronization packet generation unit 13 reads the network unique information indicated by the pointer in the network unique information storage unit 19 and generates a synchronization signal. The network unique information storage unit 19 stores network unique information when a new network is detected by the synchronization processing unit 17.

  Further, when a predetermined condition is satisfied, the synchronization processing unit 17 deletes the network specific information from the network specific information storage unit 19. The network unique information is deleted from the network unique information storage unit 19 when, for example, information from the base node of the network is not received for a predetermined time, that is, when an abnormality of the network is detected.

  FIG. 8 is a diagram illustrating an example of information for specifying a hopping pattern included in the payload of the beacon packet in the wireless communication network system 100 according to the first embodiment. In the first embodiment, a GW-ID, a frame number, a timer ID, a subslot number, and a channel order are added to the payload of the beacon packet as the synchronization signal as information for specifying the hopping pattern.

  The GW-ID is the node address of the GW that is the source of the beacon packet. For example, the value of GW-ID is used to determine whether or not the synchronization signal includes new NW information.

  The frame number is a frame number in which the beacon packet is transmitted. The frame number is given by the GW.

  The timer ID is a value that the GW increments for each beacon transmission. The timer ID is used to determine whether the beacon packet is new or old. Note that the number of beacon packets transmitted in one use of the scan channel may be one or more.

  The subslot number is a subframe number used when the beacon packet is transmitted. The channel order is a number indicating the position from which the scan channel at the time when the beacon packet is transmitted is located in the hopping pattern of one frame.

  For example, the GW-ID and the frame number are parameters used for generating a hopping pattern. For example, the timer ID, the subslot number, and the channel order are information used to specify the use start point in the generated hopping pattern. Note that the example shown in FIG. 8 is an example, and any of the information included in the synchronization signal may be used as information used to specify the hopping pattern. For example, the information used to generate the hopping pattern may be information that is included in the synchronization signal and has a different value for each network. The GW-ID, frame number, timer ID, subslot number, and channel order shown in FIG. 8 are examples of “information that can specify the transition order of communication channels used in the network”.

<Process flow>
FIG. 9A and FIG. 9B are examples of flowcharts of processing of the node 1 when a synchronization signal of a network different from the currently synchronized network is received. The process shown in FIG. 9A is started when the node 1 receives the synchronization signal. The execution subject of the processing shown in FIGS. 9A and 9B is the control unit 101 of the node 1 that executes the channel hopping control program 102P stored in the memory 102. For convenience, the synchronization processing unit 17 that is a functional component is provided. Explain as the subject. 9A and 9B are based on the premise that the hopping pattern of the synchronized NW is stored in the first NW synchronization information management table 18A.

  In OP1, the synchronization processing unit 17 determines whether or not the received synchronization signal is a synchronization signal including information on another network different from the currently synchronized network. This determination is performed based on, for example, whether or not the value of the GW-ID in the example illustrated in FIG. 8 matches the GW of the currently synchronized network.

  When the received synchronization signal is a synchronization signal including information on another network different from the currently synchronized network (OP1: YES), the process proceeds to OP2. When the received synchronization signal is not a synchronization signal including information on another network different from the currently synchronized network (OP1: NO), the processing shown in FIG. 9A ends.

  In OP2, the synchronization processing unit 17 calculates the communication quality of the network that is the transmission source of the synchronization signal based on the received synchronization signal, and determines whether or not the communication quality of the currently synchronized network is better. If the communication quality of the transmission source network of the received synchronization signal is better than the communication quality of the currently synchronized network (OP2: YES), the process proceeds to OP11 in FIG. 9B. If the communication quality of the currently synchronized network is equal to or higher than the communication quality of the transmission source network of the received synchronization signal (OP2: NO), the process proceeds to OP3. The process of OP2 is an example of a process for selecting a network to be synchronized. That is, in the YES determination in OP2, it is determined to change the synchronization destination network.

In OP3, the synchronization processing unit 17 determines whether or not the source network of the received synchronization signal is a new network. This determination is made, for example, by the network specific information storage unit 19.
Is performed based on whether or not there is information that matches the network unique information included in the received synchronization signal. If the source network of the received synchronization signal is a new network (OP3: YES), the process proceeds to OP4. If the source network of the received synchronization signal is not a new network (OP3: NO), the process shown in FIG. 9A ends.

  The processing from OP4 to OP8 is processing when the source network of the received synchronization signal is a new NW, but the currently synchronized NW has better communication quality and is not selected as a synchronized NW.

  In OP4, the synchronization processing unit 17 stores the network unique information included in the received synchronization signal in the network unique information storage unit 19. In OP5, the synchronization processing unit 17 determines whether or not a hopping pattern is stored in the second NW synchronization information management table 18B. When the hopping pattern is stored in the second NW synchronization information management table 18B (OP5: YES), the process proceeds to OP6. When the hopping pattern is not stored in the second NW synchronization information management table 18B (OP5) : NO), the process proceeds to OP7.

  In OP6, the synchronization processing unit 17 determines whether the communication quality of the network from which the synchronization signal received is better than the network in which the hopping pattern is stored in the second NW synchronization information management table 18B. When the communication quality of the transmission source network of the received synchronization signal is better than the network in which the hopping pattern is stored in the second NW synchronization information management table 18B (OP6: YES), the process proceeds to OP7.

  When the communication quality of the network of the transmission source of the received synchronization signal is equal to or lower than the communication quality of the network in which the hopping pattern is stored in the second NW synchronization information management table 18B (OP6: NO), the processing shown in FIG. 9A Ends. In this case, the hopping pattern of the network that is the transmission source of the received synchronization signal is not generated.

  In OP7, the synchronization processing unit 17 creates a network hopping pattern included in the received synchronization signal using the network specific information included in the received synchronization signal. In OP8, the synchronization processing unit 17 stores the created hopping pattern in the second NW synchronization information management table 18B. Thereafter, the process illustrated in FIG. 9A ends.

  The process shown in FIG. 9B is a process when the network of the transmission source of the received synchronization signal has better communication quality and the network of the transmission source of the received synchronization signal is selected as a synchronized network. Hereinafter, the network of the transmission source of the received synchronization signal newly selected as the synchronization destination is referred to as a new NW.

  In OP11, the synchronization processing unit 17 determines whether the network in which the hopping pattern is stored in the second NW synchronization information management table 18B and the new NW are the same. When the network in which the hopping pattern is stored in the second NW synchronization information management table 18B and the new NW are the same (OP11: YES), the process proceeds to OP14. When the network in which the hopping pattern is stored in the second NW synchronization information management table 18B and the new NW are not the same (OP11: NO), the process proceeds to OP12.

  In OP12, the synchronization processing unit 17 generates a hopping pattern for the new NW using the unique information for the new NW. In OP13, the synchronization processing unit 17 stores the generated hopping pattern in the second NW synchronization information management table 18B.

In OP14, the synchronization processing unit 17 performs synchronization preparation processing for the new NW and starts synchronization with the new NW. For example, in OP14, the synchronization processing unit 17 sets a pointer indicating the currently synchronized NW in the network unique information storage unit 19 to point to the unique information of the new NW. For example, in OP14, the synchronization processing unit 17 instructs the synchronization packet generation unit 13 and the channel transition unit 15 to switch the table to be referenced to the second NW synchronization information management table 18B.

  In OP15, the synchronization processing unit 17 determines whether or not it is necessary to transmit a synchronization signal including information on the new NW to the previous NW. This determination is performed based on, for example, the number of executions of transmission of a synchronization signal including information on the new NW to the previous NW, or the elapsed time since synchronization with the new NW.

  When it is determined to execute transmission of a synchronization signal including information on the new NW to the previous NW (OP15: YES), the process proceeds to OP16. When it is determined not to execute transmission of a synchronization signal including information on the new NW to the previous NW (OP15: NO), the process proceeds to OP17.

  In OP16, the synchronization processing unit 17 starts determining the scan channel use timing according to the hopping pattern of the previous NW from the start point of the frame # n + 1 one frame after the frame #n where the synchronization with the new NW is started. When the synchronization processing unit 17 determines the use timing of the scan channel according to the hopping pattern of the previous NW, the channel transition unit 15 causes the channel transition unit 15 to transition to the scan channel, and causes the synchronization packet generation unit 13 to transmit a synchronization signal including the unique information of the new NW. .

  Specifically, when the synchronization processing unit 17 determines the use timing of the scan channel according to the hopping pattern of the previous NW, the table referred to the synchronization packet generation unit 13 and the channel transition unit 15 is switched to the first NW synchronization information management table 18A. Instruct. As a result, the channel transition unit 15 instructs the channel setting unit 16 to set the scan channel to the use channel according to the hopping pattern of the previous NW. In addition, the synchronization packet generation unit 13 generates a synchronization signal including information on the new NW at the timing when the scan channel is used according to the hopping pattern of the previous NW, and outputs the synchronization signal to the transmission unit 11. However, at this time, the pointer of the NW unique information storage unit 19 points to the unique information of the new NW, and the synchronization signal generated by the synchronization packet generator 13 includes the unique information of the new NW.

  When the synchronization processing unit 17 determines the timing of transition from the scan channel to another channel according to the hopping pattern of the previous NW, the table referred to the synchronization packet generation unit 13 and the channel transition unit 15 is stored in the second NW synchronization information management table 18B. Instruct to switch. As a result, the synchronization packet generator 13 and the channel transition unit 15 operate according to the new NW hopping pattern.

  Thereafter, for example, the processes of OP15 and OP16 are performed until the number of executions of transmission of the synchronization signal including the information of the new NW to the previous NW reaches a predetermined number or until a predetermined time elapses after synchronization with the new NW. It is done repeatedly.

  In OP17, the synchronization processing unit 17 does not need to transmit a synchronization signal including information on the new NW to the previous NW, and therefore deletes the hopping pattern of the previous NW. Thereafter, the process shown in FIG. 9B ends. In the first embodiment, the hopping pattern of the previous NW is held in the first NW synchronization information management table 18A, and the hopping pattern of the new NW is held in the second NW synchronization information management table 18B. In OP17, when the hopping pattern of the previous NW is deleted, the synchronization processing unit 17 uses the table treated as the second NW synchronization information management table 18B, in the first embodiment, the first NW synchronization information management table hereinafter. It will be handled as 18A.

  FIG. 10 is an example of a flowchart of processing of the node 1 when an abnormality of the network being synchronized is detected. The process shown in FIG. 10 is started when the node 1 detects a network abnormality. The execution subject of the process shown in FIG. 10 is the control unit 101 of the node 1 that executes the channel hopping control program 102P stored in the memory 102, but for convenience, the synchronization processing unit 17 that is a functional component will be mainly described. To do.

  In OP21, the synchronization processing unit 17 determines whether an abnormality of the network being synchronized has been detected. If a network abnormality during synchronization is detected (OP21: YES), the process proceeds to OP22. If no network abnormality is detected during synchronization (OP21: NO), the processing shown in FIG. 10 ends.

  In OP22, the synchronization processing unit 17 determines whether or not a hopping pattern is stored in the second NW synchronization information management table 18B. If the hopping pattern is stored in the second NW synchronization information management table 18B (OP22: YES), the process proceeds to OP27. When the hopping pattern is not stored in the second NW synchronization information management table 18B (OP22: NO), the process proceeds to OP23.

  In OP23, the synchronization processing unit 17 performs a network search process. Specifically, the synchronization processing unit 17 instructs the channel transition unit 15 to stop channel hopping and set the scan channel to be a use channel.

  In OP24, the synchronization processing unit 17 determines whether or not a synchronization signal including information on another NW different from the NW in which the abnormality is detected is received. When a synchronization signal including information on another NW different from the NW in which the abnormality is detected is received (OP24: YES), the network from which the synchronization signal is transmitted is selected as the synchronization destination, and the process proceeds to OP25. . When a synchronization signal including information on another NW different from the NW in which an abnormality is detected is not received (OP24: NO), the processes of OP23 and OP24 are repeated.

  After OP25, processing similar to that after OP12 in FIG. 9B is performed. In OP25, the synchronization processing unit 17 sets the network of the source of the received synchronization signal as the new NW, and generates a hopping pattern for the new NW using the unique information of the new NW. In OP26, the synchronization processing unit 17 stores the generated hopping pattern in the second NW synchronization information management table 18B.

  In OP27, the synchronization processing unit 17 performs synchronization preparation processing for the new NW and starts synchronization with the new NW. In OP28, the synchronization processing unit 17 determines whether or not it is necessary to transmit a synchronization signal including information on the new NW to the previous NW. If it is determined that transmission of a synchronization signal including information on the new NW to the previous NW is determined (OP28: YES), the process proceeds to OP29. When it is determined not to execute transmission of a synchronization signal including information on the new NW to the previous NW (OP28: NO), the process proceeds to OP30.

  In OP29, the synchronization processing unit 17 determines the use timing of the scan channel according to the hopping pattern of the previous NW, causes the channel transition unit 15 to transition to the scan channel, and the synchronization packet generation unit 13 includes the synchronization signal including the unique information of the new NW. To send. Thereafter, for example, the processing of OP28 and OP29 is performed until the number of executions of the transmission of the synchronization signal including the information of the new NW to the previous NW reaches a predetermined number or until a predetermined time elapses after synchronization with the new NW. It is done repeatedly.

  In OP30, the synchronization processing unit 17 does not need to transmit a synchronization signal including information on the new NW to the previous NW, and therefore deletes the hopping pattern of the previous NW. Thereafter, the process shown in FIG. 10 ends.

  FIG. 11 is a diagram illustrating an example of channel transition between the node # 1 and the node # 2 when an abnormality of the network being synchronized is detected. FIG. 11 shows the node # 1 and the node # 2 shown in FIG. Further, it is assumed that, at the start point of frame # 0 in FIG. 11, node # 2 detects an abnormality in NW # 1 that is in synchronization. Further, in the example illustrated in FIG. 11, it is assumed that the node # 2 is in a state where it does not receive the synchronization signal including the information of NW # 2.

  When node # 2 detects an abnormality in NW # 1 that is in synchronization (FIG. 10, OP21: YES), the hopping pattern is not stored in the second NW synchronization information management table 18B (FIG. 10, OP22: NO). ) The network search process is started (FIG. 10, OP23). In the network search process, channel hopping is stopped and the scan channel is used. Therefore, in frame # 0 in FIG. 11, the used channel of node # 2 is the scan channel.

  Therefore, at the scan channel usage timing according to the hopping pattern of NW # 2 (node # 1) of frame # 0, the scan channel usage timings of node # 2 and NW # 2 match, and node # 2 is NW A synchronization signal including the information of # 2 is received (FIG. 10, OP24: YES). Thereafter, the node # 2 performs a synchronization preparation process, and starts synchronization to the NW # 2 from the start point of the frame # 2.

  FIG. 12 is a diagram illustrating an example of channel transition between the node # 1 and the node # 2 when an abnormality of the network being synchronized is detected. In FIG. 12, similarly to FIG. 11, the nodes # 1 and # 2 shown in FIG. 1 are shown. In FIG. 12, similarly to FIG. 11, it is assumed that at the start point of frame # 0, node # 2 detects an abnormality in NW # 1 that is in synchronization. In the example shown in FIG. 12, the node # 2 has received the synchronization signal including the information of NW # 2, and holds the hopping pattern of NW # 2 in the second NW synchronization information management table 18B. Assuming that

  When node # 2 detects an abnormality in NW # 1 that is in synchronization (FIG. 10, OP21, YES), the hopping pattern of NW # 2 is held in the second NW synchronization information management table 18B (FIG. 10). , OP22: YES), synchronization preparation processing to NW # 2 is performed (FIG. 10, OP27). Thereafter, the node # 2 starts synchronization with the NW # 2 from the start point of the frame # 2.

  FIG. 13 is a diagram illustrating an example of channel transition of the node # 1 to the node # 4 following the example illustrated in FIG. 11 or FIG. Since node # 2 holds the hopping patterns of NW # 1 and NW # 2, channel transition (upper stage) according to the hopping pattern of NW # 2, which is the new NW, and NW #, which is the previous NW A channel transition (lower stage) according to a hopping pattern of 1 is shown. Further, both the node # 3 and the node # 4 are in a state of not receiving the synchronization signal including the information of NW # 2.

  Each of the node # 3 and the node # 4 detects an abnormality of the synchronized NW # 1 (FIG. 10, OP21: YES), and performs a network search process (FIG. 10, OP23). That is, the channel used by node # 3 and node # 4 is a scan channel (channel # 1) in any subframe in frame # 2 and frame # 3.

Node # 2 starts synchronization with NW # 2 in frame # 2, and determines the timing of transition from the start point of the next frame # 3 to the scan channel according to the hopping pattern of NW # 1. Node # 2 determines that the start point of the second subframe of frame # 3 is the timing of transition to the scan channel according to the hopping pattern of NW # 1, transitions to the scan channel, and stores the information of NW # 2 Send a sync signal containing.

  When the node # 3 and the node # 4 transition to the scan channel according to the hopping pattern of the NW # 1 in the frame # 3, the node # 3 and the node # 4 receive the synchronization signal including the information of the NW # 2 transmitted from the node # 2. Thereby, the node # 3 and the node # 4 can know the existence of the NW # 2. Each of the node # 3 and the node # 4 determines the change of the synchronization destination to the NW # 2 with better communication quality, and performs the synchronization preparation processing to the NW # 2, for example, from the frame # 5 to the NW # 2 Start syncing.

<Operational effects of the first embodiment>
In the first embodiment, when NW # 2 is selected as the new NW to be synchronized, the node # 2 uses any communication channel according to the hopping pattern of the previous NW # 1, and uses the hopping pattern of the new NW # 2. Send information that can be specified. As a result, the nodes # 3 and # 4 whose channels are changed according to the hopping pattern of the previous NW # 1 are allowed to receive information that can identify the hopping pattern of the new NW # 2 with the hopping pattern of the previous NW # 1. Can do. For example, when the new NW # 2 has better communication quality, the node # 3 and the node # 4 that are synchronized with the previous NW # 1 indicate information that can identify the hopping pattern of the new NW # 2 By receiving with the # 1 hopping pattern, wireless communication using the new NW # 2 can be started promptly.

  Further, the information that can identify the hopping pattern of each NW and the unique information of the NW included in the synchronization information according to the first embodiment is an example of data advertised in each NW. Also, according to the first embodiment, when the node # 2 receives the NW # 2 synchronization signal and changes the NW # 1 hopping pattern to the NW # 2 hopping pattern, the advertisement data in the NW # 2 Is an example of changing the transmission timing of advertisement data and data in a frame from the transmission timing in NW # 1 to the transmission timing in NW # 2. In addition, after the node # 2 according to the first embodiment synchronizes with the new NW, the information that can identify the hopping pattern of the new NW with the hopping pattern of the previous NW is transmitted at least one unit after the transmission timing is changed. This is an example of transmitting advertisement data in the new NW at the transmission timing of advertisement data in the previous NW in time. Therefore, according to the first embodiment, the advertisement data in the new NW can be promptly notified to the nodes in the previous NW with the advertisement data of the previous NW.

  In the first embodiment, the node # 2 transmits a synchronization signal including the hopping pattern of the new NW using the scan channel according to the hopping pattern of the previous NW. The scan channel is a representative channel whose use channel is known in any wireless communication standard. The synchronization signal is a typical signal transmitted by multicast or broadcast. Therefore, the technology described in the first embodiment can be easily applied to a wireless communication network conforming to any wireless communication standard by using a scan channel and a synchronization signal for transmitting information of the new NW to the previous NW. can do.

  In the first embodiment, the node # 2 repeatedly transmits information that can specify the hopping pattern of the new NW using a predetermined channel according to the hopping pattern of the previous NW for a predetermined period or a predetermined number of times. To do. As a result, the node 1 in the previous NW can reliably notify information that can specify the hopping pattern of the new NW.

Further, in the first embodiment, when the node # 2 completes transmitting information that can specify the hopping pattern of the new NW # 2 using a predetermined channel according to the hopping pattern of the previous NW # 1, The hopping pattern of the previous NW # 1 is deleted from the first NW synchronization information management table 18A. As a result, the memory holding the hopping pattern of the previous NW # 1 can be released, and when a new NW is detected, the hopping pattern of the NW can be held.

  In the first embodiment, when the synchronization destination is changed to the new NW # 2, the node # 2 performs channel transition according to the hopping pattern of the new NW # 2. Thereby, the node # 2 determines the transition to the predetermined channel according to the hopping pattern of the previous NW # 1, and when transitioning from the predetermined channel to another channel, the transition is performed according to the hopping pattern of the new NW # 2. Determine the other channel. Therefore, the node # 2 can notify the previous NW # 1 of the information of the new NW # 2 while executing the communication of the new NW # 2.

  Further, in the first embodiment, the node # 2 executes the network search process when the abnormality of the NW # 1 is detected and the hopping pattern of the NW # 2 is not held. Thus, even when the node # 2 does not hold the hopping pattern of NW # 2, it can actively detect NW # 2 and acquire the hopping pattern from the synchronization signal of NW # 2.

  In the first embodiment, the node # 2 receives the synchronization signal of the NW # 2 while synchronizing with the NW # 1, and if the change of the synchronization destination to the NW # 2 is not determined, the node # 2 A hopping pattern is generated and stored. After that, when a communication abnormality of NW # 1 is detected, or when it is determined that the synchronization destination is changed to NW # 2, node # 2 uses the stored hopping pattern of NW # 2. Then, a synchronization preparation process for node # 2 is performed. As a result, when an event for changing the synchronization destination to the new NW occurs, the process of generating a hopping pattern can be omitted, and the synchronization destination can be changed to the new NW more quickly.

  In the first embodiment, when the node # 2 receives synchronization signals for a plurality of networks other than the NW # 1 while synchronizing with the NW # 1, the node # 2 communicates most among the plurality of networks. Store hopping patterns for high quality networks. As a result, memory consumption due to storage of the hopping pattern can be reduced.

<Others>
In the first embodiment, information that can specify a hopping pattern is included in a synchronization signal and transmitted through a scan channel. However, the information that can specify the hopping pattern is not limited to being transmitted by being included in the synchronization signal in the scan channel. For example, information that can specify a hopping pattern can be used if it is a message that is transmitted by multicast or broadcast, and a channel that can be used for transmitting the message can be specified.

  Further, the information on the new NW that is to be notified to the nodes in the previous NW may be included in the synchronization signal with information other than information that can specify the hopping pattern. As an example of the new NW information included in the synchronization signal other than the information that can specify the hopping pattern, there is parameter information indicating the priority of the new NW used for selection of the synchronization destination network by the node.

<Recording medium>
A program for causing a computer or other machine or device (hereinafter, a computer or the like) to realize any of the above functions can be recorded on a recording medium that can be read by the computer or the like. The function can be provided by causing a computer or the like to read and execute the program of the recording medium.

Here, a computer-readable recording medium is a non-temporary recording medium in which information such as data and programs is accumulated by electrical, magnetic, optical, mechanical, or chemical action and can be read from a computer or the like. A typical recording medium. Examples of such a recording medium that can be removed from a computer or the like include a flexible disk, a magneto-optical disk, a CD-ROM, a CD-R / W, a DVD, a Blu-ray disk, a DAT, an 8 mm tape, a flash memory, and the like. There are cards. In addition, as a recording medium fixed to a computer or the like, there are a hard disk, a ROM (read only memory), and the like. Further, an SSD (Solid State Drive) can be used as a recording medium removable from a computer or the like, or as a recording medium fixed to the computer or the like.

<Processor>
In the above embodiment, the node 1 includes the control unit 101, and executes the described process by executing an instruction expanded from a program in the memory 102. The control unit 101 includes, for example, a CPU. The CPU is also called an MPU (Microprocessor) or processor. The CPU is not limited to a single processor, and may have a multiprocessor configuration. A single CPU connected by a single socket may have a multi-core configuration. At least a part of the processing of each unit may be performed by a processor other than the CPU, for example, a dedicated processor such as a digital signal processor (DSP), a graphics processing unit (GPU), a numerical operation processor, a vector processor, or an image processing processor. good. In addition, at least a part of the processing of each unit may be an integrated circuit (IC) or other digital circuit. In addition, an analog circuit may be included in at least a part of each of the above parts. The integrated circuit includes an LSI, an application specific integrated circuit (ASIC), and a programmable logic device (PLD). The PLD includes, for example, a field-programmable gate array (FPGA). Each of the above units may be a combination of a processor and an integrated circuit.
The combination is called, for example, a microcontroller (MCU), a SoC (System-on-a-chip), a system LSI, a chip set, or the like.

1 node 11 transmitting unit 12 receiving unit 13 synchronization packet generating unit 14 timer 15 channel transition unit 16 channel setting unit 17 synchronization processing unit 18A first network synchronization information management table 18B second network synchronization information management table 19 network specific information storage unit 100 Wireless communication network system 101 Control unit 102 Memory 103 Wireless unit 104 Clock 105 Power feeding unit 106 Antenna

Claims (11)

Wireless communication device
Make wireless communication while changing the communication channel to be used,
The transition order of communication channels used in the first network is stored in the storage unit,
When performing wireless communication using a second network in which wireless communication is performed according to the transition order of communication channels, at a timing when a predetermined communication channel is used according to the transition order of communication channels used in the first network, Using the predetermined communication channel, transmitting information capable of specifying the transition order of communication channels used in the second network;
Wireless communication control program for In the wireless communication device,
In the transmission, the predetermined communication channel is a channel used for transmission of a synchronization signal for synchronizing operation timing between wireless communication devices, and the transition order of communication channels used in the second network can be specified. To send information
The wireless communication control program according to claim 1. In the wireless communication device,
The transmission is performed for a predetermined period or a predetermined number of times.
The wireless communication control program according to claim 1 or 2. In the wireless communication device,
When the transmission is completed, the transition order of communication channels used in the first network is deleted from the storage unit.
The wireless communication control program according to any one of claims 1 to 3. In the wireless communication device,
When wireless communication is performed using the second network, wireless communication in the second network is performed using a communication channel according to a transition order of communication channels used in the second network.
The wireless communication control program according to any one of claims 1 to 4. In the wireless communication device,
Used to synchronize operation timing between wireless communication devices when a communication abnormality in the first network is detected and the transition order of communication channels used in the second network is not maintained. Search for another network using a channel used for transmission of a synchronization signal, detect the second network, and acquire information that can specify the transition order of communication channels used in the second network ,
The wireless communication control program according to any one of claims 1 to 5. In the wireless communication device,
In a state in which communication is performed while transitioning communication channels according to the transition order of communication channels used in the first network, information that can specify the transition order of communication channels used in the second network is received. In addition, when wireless communication is not performed using the second network, the transition order of communication channels used in the second network is specified, and the communication channel used in the specified second network is specified. Is stored in the storage unit when wireless communication is performed using the second network, or when a communication abnormality of the first network is detected. Wireless communication according to the transition order of communication channels used in the second network. It is allowed to practice,
The wireless communication control program according to any one of claims 1 to 6. In the wireless communication device,
The transition order of communication channels used in the network with the highest communication quality among the plurality of networks when receiving information that can specify the transition order of communication channels for a plurality of networks other than the first network. Is specified and stored in the storage unit,
The wireless communication control program according to any one of claims 1 to 7. A wireless communication unit that performs wireless communication while changing a communication channel to be used;
A storage unit for storing a transition order of communication channels used in the first network;
When performing wireless communication using a second network in which wireless communication is performed according to the transition order of communication channels, at a timing when a predetermined communication channel is used according to the transition order of communication channels used in the first network, A control unit for determining transmission of information capable of specifying a transition order of communication channels used in the second network from the wireless communication unit in a predetermined communication channel;
A wireless communication device comprising: Wireless communication device
Perform wireless communication while changing the communication channel to be used,
Storing a transition order of communication channels used in the first network in a storage unit;
When performing wireless communication using a second network in which wireless communication is performed according to the transition order of communication channels, at a timing when a predetermined communication channel is used according to the transition order of communication channels used in the first network, Using the predetermined communication channel, transmitting information that can specify the transition order of communication channels used in the second network;
Wireless communication control method. Wireless communication device
The wireless communication is executed in the first network while changing the communication channel to be used,
When advertisement data in the second network is received from another wireless communication apparatus belonging to the second network, the transmission timing of the advertisement data and data in unit time is set as the transmission timing in the first network. To the transmission timing in the second network,
After the change of the transmission timing, the advertisement data in the second network is transmitted at the transmission timing of the advertisement data in the first network in at least one unit time.
Wireless communication control program.

Images