WO2019211906A1 - Wireless node, wireless link establishing method, and wireless link establishing program - Google Patents

Abstract

This wireless node is provided with: a transmission unit that transmits, when a first association request signal for a first beacon signal is received after the first beacon signal has been transmitted, a first response signal to a transmission source of the first association request signal; a reception unit that receives a second response signal with respect to a second association request after the second association request has been transmitted to a transmission source of a second beacon signal in response to reception of the second beacon signal; and a management unit that manages information about a wireless link between a transmission source of the first beacon signal and the transmission source of the first association request signal in response to transmission of the first response signal, and manages information about a wireless link between a transmission source of the second association request and the transmission source of the second beacon signal in response to reception of the second response signal.

Description

Wireless node, wireless link establishment method, and wireless link establishment program

The present invention relates to a wireless node, a wireless link establishment method, and a wireless link establishment program.

In an existing cellular communication system, a base station that provides a radio access line for user equipment and a backbone network (sometimes referred to as a core network) are connected by a wired backhaul (BH) network. Many.

On the other hand, as one form for realizing a new generation of mobile communication, a plurality of wireless nodes (for example, base stations or access points) providing a wireless communication area with a radius of several tens of meters are connected by wireless multi-hop. A system or network is under consideration.

For example, by making the BH network, which is one of the mobile communication infrastructures, wireless by multi-hop, it is possible to eliminate the need for laying a wired cable and to reduce the laying cost required for the introduction of the mobile communication system.

JP 2005-143046 A International Publication No. 2011/105371

As a form of wireless multi-hop connection, for example, a network having a tree structure having a specific wireless node among a plurality of wireless nodes at the apex is considered. In a network having a tree structure, it is considered that a wireless link with a mesh-like link up is constructed, and a wireless link having a tree structure is selected as a transmission path from the wireless link with the mesh-like link up.

It is considered to use the IBSS mode as a method for constructing a meshed link-up wireless link. However, some wireless nodes do not support the IBSS mode, and a mesh-like link-up wireless link may not be established.

One of the objects of the present invention is to construct a mesh link even for a wireless node that does not support the IBSS mode.

The wireless node according to an aspect is one of a plurality of wireless nodes, and when the first association request signal for the first beacon signal is received after transmitting the first beacon signal, A transmission unit that transmits a first response signal to a transmission source of the first association request signal; and a second association request transmitted to the transmission source of the second beacon signal in response to reception of the second beacon signal; Radio between the receiving unit that receives the second response signal for the association request, the transmission source of the first beacon signal, and the transmission source of the first association request signal in response to the transmission of the first response signal Storing link information, and receiving the second response signal in response to receiving the second response signal. Comprising a source of the Activation request, the transmission source of the second beacon signal, and a management unit for managing information of the radio link between the.

Further, the wireless link establishment method according to one aspect is configured such that, after transmitting the first beacon signal, when the first association request signal for the first beacon signal is received, the transmission source of the first association request signal is first A response signal is transmitted, a second association request is transmitted to the transmission source of the second beacon signal in response to the reception of the second beacon signal, and then a second response signal for the second association request is received; In response to the transmission of the response signal, information on the radio link between the transmission source of the first beacon signal and the transmission source of the first association request signal is managed, and in response to the reception of the second response signal , The source of the second association request and the transmission of the second beacon signal To management source and the information of the wireless link between the.

In addition, the wireless link establishment program according to one aspect is configured such that, when a first association request signal for the first beacon signal is received after the first beacon signal is transmitted to the processor, the transmission source of the first association request signal Transmitting a first response signal to the second beacon signal in response to receiving the second beacon signal, and then receiving a second response signal for the second association request after transmitting the second association request to the transmission source of the second beacon signal; In response to the transmission of the first response signal, the wireless link information between the transmission source of the first beacon signal and the transmission source of the first association request signal is managed, and the reception of the second response signal Depending on the source of the second association request, and It manages the source of the 2 beacon signal, information of the radio link between, to execute the process.

A mesh link can be established even for a wireless node that does not support the IBSS mode.

It is a block diagram which shows the structural example of the radio | wireless communications system which concerns on 1st Embodiment. It is a figure which shows an example of the connection form between the nodes which concerns on 1st Embodiment with the protocol stack of each node. It is a block diagram which shows the hardware structural example of the node which concerns on 1st Embodiment. It is a block diagram which shows the functional structural example of the node which concerns on 1st Embodiment. FIG. 5 is a block diagram illustrating a functional configuration example of a control unit illustrated in FIG. 4. It is a flowchart which shows an example of the link setup procedure between the nodes which concern on 1st Embodiment. FIG. 7 is a diagram illustrating an example in which a mesh-like wireless link is linked up between nodes by the link setup procedure illustrated in FIG. FIG. 8 is a diagram illustrating an example of peripheral node information managed in each of the nodes illustrated in FIG. 7. It is a figure which shows an example of the tree path | route control on the mesh link which concerns on 1st Embodiment. It is a figure which shows the example of selection of the link information in each of a node corresponding to the tree path | route illustrated to (A) of FIG. It is a figure which shows the selection example of the link information in each of a node corresponding to the tree path | route illustrated to (B) of FIG. It is a flowchart which shows the operation example of the core node (CN) including the tree path control on the mesh link which concerns on 1st Embodiment. It is a flowchart which shows the operation example of a slave node (SN) including the tree path control on the mesh link which concerns on 1st Embodiment. 10 is a flowchart for explaining an operation example of the CN when transmitting a data packet in the tree path constructed by the tree path control illustrated in FIG. 9. 10 is a flowchart for explaining an operation example of an SN when a data packet is transmitted in the tree path constructed by the tree path control illustrated in FIG. 9. It is a figure explaining an example of the setup procedure of the mesh link between nodes using the combination of AP (Access point) mode and STA (Station) mode based on the modification of 1st Embodiment. It is a figure which shows the setup procedure of the mesh link illustrated in FIG. 16 together with the protocol stack of each node. It is a block diagram which shows the functional structural example of the control part which concerns on 2nd Embodiment. It is a flowchart which shows an example of the link setup procedure of the node which concerns on 2nd Embodiment. It is a flowchart which shows an example of the link setup procedure of the node which concerns on 2nd Embodiment.

(First embodiment)
Embodiments will be described below with reference to the drawings as appropriate. Throughout this specification, the same elements are denoted by the same reference symbols unless otherwise specified. The following description in conjunction with the accompanying drawings is intended to illustrate exemplary embodiments and not to show the only embodiments. For example, when the order of operations is shown in the embodiment, the order of operations may be changed as appropriate as long as there is no contradiction as an overall operation.

In the case where a plurality of embodiments and / or modifications are illustrated, some configurations, functions, and / or operations in one embodiment and / or modification may be limited to other embodiments and / or operations as long as no contradiction arises. It may be included in the modification, and may be replaced with a corresponding configuration, function, and / or operation of another embodiment and / or modification.

In the embodiment, more detailed description than necessary may be omitted. For example, in order to avoid unnecessarily redundant explanations and / or to obscure technical matters or concepts, and to facilitate understanding of those skilled in the art, known or well-known technical matters The detailed description of may be omitted. In addition, redundant description of substantially the same configuration, function, and / or operation may be omitted.

The accompanying drawings and the following description are provided to assist the understanding of the embodiments and are not intended to limit the subject matter described in the claims. In addition, the terms used in the following description may be appropriately replaced with other terms in order to assist those skilled in the art.

<System configuration example>
FIG. 1 is a block diagram illustrating a configuration example of a wireless communication system according to the first embodiment. The wireless communication system 1 illustrated in FIG. 1 includes a plurality of nodes 3 exemplarily. In FIG. 1, as a non-limiting example, 15 nodes 3 indicated by node numbers # 0 to # 14 are illustrated. The number of nodes 3 may be 2 or more and less than 14, or 16 or more.

Each node 3 is an example of a wireless device capable of wireless communication. Therefore, each of the nodes 3 may be referred to as a “wireless node 3”. For wireless communication, a communication protocol based on (or based on) a wireless LAN (Local Area Network) related standard such as IEEE802.11b / g / a / n / ac / ad / ay may be applied.

Each node 3 forms an area where wireless communication is possible. The “area where wireless communication is possible” may be referred to as “wireless communication area”, “wireless area”, “communication area”, “service area”, “coverage area”, “cover area”, or the like. The wireless communication area formed by the node 3 based on or based on the wireless LAN related standard may be regarded as corresponding to a “cell” which is a name in cellular communication. For example, the wireless communication area formed by each node 3 may be regarded as corresponding to a “femto cell” classified as a “small cell”.

Each node 3 can wirelessly communicate with another node 3 when it is located in the service area of the other node 3. The plurality of nodes 3 form a wireless backhaul (BH) network 9 that relays communication between the backbone network 5 and the terminal device 7 by radio, for example. The “wireless BH network” may be referred to as a “BH network” by omitting “wireless”.

“BH network” may be referred to as “relay network”. The individual nodes 3 that are entities of the BH network 9 may be referred to as “relay nodes”.

The backbone network 5 is illustratively a large-scale communication network such as the Internet. The “backbone network” may be referred to as a “core network”, a “global network”, or the like.

A path or section in which a radio signal is transmitted in the BH network 9 is mutually connected with a “wireless BH communication path”, “wireless BH transmission path”, “wireless BH line”, “wireless BH connection”, or “wireless BH channel”. May be read as: In these terms, “wireless” may be omitted, and “BH” may be read as “relay”.

On the other hand, for example, a section in which a wireless signal is transmitted between the terminal device 7 and the BH network 9 may be referred to as a “wireless access line” or a “wireless access channel”. In these terms, “wireless” may be omitted.

In the following description, the term “signal” may be replaced with a term of a unit in which a signal is divided in time, such as “frame” or “packet”.

Different frequencies (channels) may be assigned to the wireless BH line and the wireless access line. As a non-limiting example, a frequency (channel) in the 5 GHz band (for example, 5.15 to 5.85 GHz) may be assigned to the BH line.

A frequency (channel) in the 2.4 GHz band (for example, 2.412 to 2.472 GHz) may be assigned to the access line. As long as the frequency is different from the frequency allocated to the BH line, a frequency in the 5 GHz band may be allocated to the access line.

The 5 GHz band includes, for example, at least one of a 5.2 GHz band (W52: 5150-5250 MHz), a 5.3 GHz band (W53: 5250-5350 MHz), and a 5.6 GHz band (W56: 5470-5725 MHz). May be included.

The number of channels that can be used in W52 is four channels of 36 ch, 40 ch, 44 ch, and 48 ch. The number of channels available in W53 is 4 channels of 52ch, 56ch, 60ch and 64ch. The number of channels that can be used in W56 is 11 channels of 100 ch, 104 ch, 108 ch, 112 ch, 116 ch, 120 ch, 124 ch, 128 ch, 132 ch, 136 ch, and 140 ch.

Therefore, for example, when one or two frequency bands of W52, W53, and W56 are assigned to the access line, the remaining one of W52, W53, and W56 that is not assigned to the access line is assigned to the BH line. Or two frequency bands may be assigned.

Some of the nodes 3 may be connected to the backbone network 5 by wire. FIG. 1 illustrates a mode in which two nodes # 0 and # 8 are connected to the backbone network 5 by wire. For the wired connection, for example, a LAN cable or an optical fiber cable may be applied.

The node # 0 and the node # 8 wired to the backbone network 5 may be referred to as “core nodes (CN)”. Among the plurality of nodes 3 forming the BH network 9, the individual nodes 3 excluding CN # 0 and # 8 may be referred to as “slave nodes (SN)”. For example, in FIG. 1, nodes # 1 to # 7 and # 9 to # 14 are all SNs. CN3 is an example of a “first wireless node”, and each of SN3 is an example of a “second wireless node”.

In FIG. 1, # 0 to # 14 attached to each node 3 are examples of information used to identify each node 3 (hereinafter, may be abbreviated as “node identification information”). The node identification information may be information that can uniquely identify each node 3 in the same BH network 9, and may be, for example, a node number, a device identifier, or address information. A non-limiting example of the address information is a MAC (Media Access Control) address.

The BH network 9 may have one or more tree structures (may be referred to as “tree topology”) having one CN 3 (# 0 or # 8) as a root node. For example, as shown in FIG. 1, in the BH network 9, a first tree topology with CN # 0 as a root node and a second tree topology with CN # 8 as a root node may be constructed.

In other words, in the BH network 9, a “tree topology” may be constructed for each CN3. One or more “tree topologies” constructed in the BH network 9 may be referred to as “tree clusters” or “tree subclusters”. In the BH network 9, the number of CNs 3 is not limited to two, but may be one or three or more.

In the tree topology, SN3 having no child node may be referred to as a “leaf node”, and SN3 having a child node may be referred to as an “internal node”. For example, in FIG. 1, SNs # 2, # 3, # 6, # 7, # 10, # 11, # 13, and # 14 all correspond to “leaf nodes”. Also, SNs # 1, # 4, # 5, # 9, and # 12 all correspond to “internal nodes”.

The wireless BH line may include a “downlink” in the direction from the core node 3 to the leaf node 3 and an “uplink” in the direction from the leaf node 3 to the core node 3. “Downlink” and “uplink” may be referred to as “downlink (DL)” and “uplink (UL)”, respectively, following the names in cellular communication.

The flow of signals (downlink signals) in the “downlink” may be referred to as “downstream”, and the flow of signals (uplink signals) in the “uplink” may be referred to as “upstream”. Each of the “downstream signal” and the “upstream signal” may include a control signal and a data signal. The “control signal” may include a signal not corresponding to the “data signal”.

Note that the “child node” may be considered to correspond to a node (downstream node) connected by a wireless link downstream of a certain node when attention is paid to the “downlink”. When attention is paid to the downlink, a node connected by a radio link upstream of a certain node may be referred to as a “parent node” or an “upstream node”. When attention is paid to “uplink”, the relationship between “child node” (downstream node) and “parent node” (upstream node) is reversed.

When focusing on “downlink”, “core node” may be referred to as “start node” or “start node”, and “leaf node” may be referred to as “end node” or “edge node”. May be. The “internal node” may be referred to as an “intermediate node” or a “relay node”.

The tree-structured route (tree topology) in the BH network 9 may be constructed based on, for example, a metric (hereinafter sometimes abbreviated as “route metric”) of a route from the CN 3 to a specific SN 3. For the path metric, an index (hereinafter referred to as “propagation quality index”) indicating the quality or performance of radio wave propagation in a wireless section from CN 3 to a specific SN 3 may be used.

As a non-limiting example of the propagation quality index, there is a reception power or reception intensity (for example, RSSI; Received Signal Strength Indicator), radio wave propagation loss, propagation delay, and the like of a radio signal. “Radio wave propagation loss” may be read as “path loss”.

As the propagation quality index, one or a combination of two or more selected from the above index candidates may be used. In the present embodiment, an index related to the distance of the route such as the number of hops may not be used as the propagation quality index.

For example, by transmitting a signal (for example, a control signal) from CN3 as a starting point, for each wireless section between the transmission node 3 and the receiving node 3 of the control signal, radio wave propagation loss in the wireless section is received at the receiving node 3. Can be sought.

Then, each of the receiving nodes 3 transmits the obtained radio wave propagation loss information included in the control signal, thereby transmitting the accumulated radio wave propagation loss information (in other words, cumulative) of the radio section in which the control signal has propagated. Value) can be transmitted between the nodes 3.

For example, each node 3 calculates a path metric based on a cumulative radio wave propagation loss for each upstream node candidate that is a transmission source of the control signal, and the path metric indicates, for example, the minimum among the upstream node candidates. Choose one node 3. As a result, a tree-structured path with a minimum radio wave propagation loss is constructed.

The tree-structured route (hereinafter sometimes referred to as “tree route”) can be updated dynamically or adaptively by transmitting a control signal from CN3 as a starting point or irregularly.

Hereinafter, such processing or control relating to construction and update of the tree path may be referred to as “tree path control”, “dynamic tree path control”, or “adaptive tree path control” for convenience.

Further, in the wireless BH line of the present embodiment, the downlink signal (for example, the data signal) is periodically intermittently from CN3 toward the downstream of the tree path (in other words, waiting for an intentional transmission waiting time). May be sent. Such periodic intermittent transmission may be referred to as “IPT” (Interminent Periodic Transmission).

In IPT, as described in the above-mentioned Patent Document 1, the transmission period (in other words, transmission interval or transmission frequency) of a downlink signal transmitted by CN 3 toward the downstream is changed according to the frequency reuse interval. The frequency reuse interval represents the length (distance) of a section in which occurrence of inter-node interference is suppressed on the same route and the same frequency can be reused repeatedly.

By setting the transmission cycle according to the frequency reuse interval to CN3, for example, it is possible to improve the throughput in the wireless BH line without requiring complicated congestion control, in other words, to improve the relay transmission efficiency. It becomes. In addition, the use efficiency of frequency resources in the BH network 9 can be improved.

For example, by setting the frequency reuse interval in which the occurrence of inter-node interference is suppressed to CN3, the throughput observed in the leaf node can be made independent of the number of hops even if a single frequency is used in the tree topology. , It can be kept above a certain value.

For the uplink, for example, the SN 3 transmits an uplink signal upstream according to a transmission cycle linked to a transmission cycle according to the frequency reuse interval of the downlink, thereby improving the throughput observed in the CN 3. Can do.

Therefore, for example, it is also easy to realize TDMA or TDD by assigning the same frequency (channel) to the downlink and uplink of the wireless BH line. “TDMA” is an abbreviation for Time Division Multiple Access, and “TDD” is an abbreviation for Time Division Duplex.

Therefore, it is not necessary to individually use radio IFs of different frequencies for the downlink and uplink of the wireless BH line, and it is allowed to use a common radio IF. By using a common wireless IF, the node 3 can be downsized and / or cost reduced.

However, different frequencies may be assigned to the downlink and uplink of the wireless BH line. By assigning different frequencies to the downlink and uplink of the wireless BH line, it is possible to simplify IPT control for realizing, for example, TDMA or TDD. Even when different frequencies are assigned to the downlink and uplink, the frequency resource consumption in the BH network 9 is sufficient for two channels of the downlink and uplink.

A part of the downlink and / or uplink of the BH line may include a wired line. When a wired line is included in a part of the downlink and / or uplink of the BH line, the route metric of the wired section may be calculated by a predetermined value (for example, the minimum value) smaller than the propagation loss of the wireless section.

The terminal device 7 communicates with the backbone network 5 via the BH line by connecting to any one of the plurality of SNs 3 forming the BH network 9 by a wireless access line when located in the service area of any SN 3. . The terminal device 7 may be connected to any of SN3 (in FIG. 1, as an example, SN # 14) by a wired line (wired IF). As a non-limiting example, the terminal device 7 may be a mobile terminal such as a mobile phone, a smartphone, or a tablet terminal.

Examples of wireless access lines include CDMA (Code Division Multiple Access), FDMA (Frequency Division Multiple Access), TDMA (Time Division Multiple Access), OFDMA (Orthogonal Frequency Division Multiple Access), and SC-FDMA (Single Any one of Carrier Frequency Division Multiple Access) may be applied. OFDMA may be implemented by a wireless technology such as IEEE 802.11, IEEE 802.16, LTE (Long Term Evolution), LTE-Advanced, or the like.

MIMO (Multiple Input Multiple Output) technology using an antenna array having a plurality of antenna elements may be applied to all or part of the downlink and / or uplink in the wireless BH line and / or wireless access line.

For example, beam forming using an antenna array may be performed in the downlink and / or uplink in any one or more sections between CN3 and SN3, between SN3 and SN3, and between SN3 and terminal device 7. Good.

In the following, the term “transmission” of a signal is interchanged with other terms such as “relay”, “forwarding”, “propagation”, “transmission”, “routing”, or “forwarding” of the signal. May be. The “relay” of the signal may be read as “bridge” of the signal.

Also, the term “transmission” of a signal may include the meaning of “flooding”, “broadcast”, “multicast”, or “unicast” of the signal. The term “connection” of a line may be taken to mean a state where a wired and / or wireless communication link is “established” or “linked up”.

The term “apparatus” may be interchanged with the terms “circuit”, “device”, “unit”, or “module”. The term “interface (IF)” may be interchanged with the terms “adapter”, “board”, “card”, or “module”, “chip”.

The term “terminal equipment” refers to mobile station, mobile terminal, subscriber station, mobile unit, subscriber unit, wireless unit, remote unit, mobile device, wireless device, wireless communication device, remote device, mobile subscriber station, access The terms terminal, mobile terminal, wireless terminal, remote terminal, handset, user agent, mobile client, or client may be used interchangeably.

The node 3 and / or the terminal device 7 may be an IoT (Internet of Things) device. With IoT, various “things” can be equipped with a wireless communication function. Various “things” equipped with a wireless communication function can communicate by connecting to the backbone network 5 via a wireless access line and / or a wireless BH line.

For example, the IoT device may include a sensor device or meter (measuring instrument) having a wireless communication function. A device having a sensing function and / or a monitoring function such as a monitoring camera and / or a fire alarm equipped with a sensor device and / or meter may correspond to the node 3 and / or the terminal device 7. Therefore, the BH network 9 may correspond to, for example, a sensor network and / or a monitoring network. Note that wireless communication by an IoT device may be referred to as MTC (Machine Type Communication). For this reason, the IoT device may be referred to as an “MTC device”.

<Example of protocol stack of node 3>
FIG. 2 shows an example of a connection form between the nodes 3 together with a protocol stack of each node 3. FIG. 2 shows CN3 connected to the backbone network 5 via a wired line, and two SN3s connected to CN3 via a multi-hop connection via a wireless BH line.

2 may correspond to, for example, CN # 0 in FIG. 1, and two SN3 in FIG. 2 may correspond to SN # 1 and SN # 5 in FIG. 1, respectively. Further, the terminal device 7 can be connected to the SN # 5 through a wireless access line.

As shown in FIG. 2, each of the nodes 3 includes, for example, a physical (PHY) layer (layer 1: L1), a MAC layer (layer 2: L2), a relay layer, and an upper layer higher than the layer 3 (L3). A protocol stack composed of The upper layer may include, for example, a TCP / IP layer and / or an application layer. “TCP / IP” is an abbreviation for “Transmission Control Protocol / Internet Protocol”.

Since the “relay layer” is located in an intermediate layer between the layer 2 and the layer 3 in the protocol stack, it may be expressed as “layer 2.5 (L2.5)” for convenience. The processing of the relay layer may include the processing related to “adaptive tree path control” and / or the processing (or control) related to “IPT”.

Since the “relay layer” is positioned as an intermediate layer between the layer 2 and the layer 3, it is not necessary to modify the existing MAC layer process, so the “relay layer” process can be easily implemented. The relay layer process may be implemented by one or more selected from software, middleware, firmware, and hardware.

The physical layer of the node 3 provides, for example, one wired connection (wired port) and two wireless connections (wireless ports). For convenience, in FIG. PHY "port. One of the two wireless ports is for a BH line, and the other of the two wireless ports is for an access line. “Port” may be read as “interface (IF)”.

In FIG. 2, for convenience, the MAC layer is divided into three parts so that the correspondence with the three PHY ports of the physical layer can be easily understood visually. However, the MAC layer processing may be common to each PHY port.

In FIG. 2, when attention is paid to the flow of the downlink signal, the downlink signal received from the backbone network 5 at CN # 0 is transmitted to the CN # 0 wired port (L1), MAC layer (L2), and relay layer (L2). .5) is transmitted from the radio port for the BH line to the downstream BH line.

The downlink signal transmitted by CN # 0 to the BH line is received by the wireless port for the BH line in SN # 1, which is the next hop, and is transmitted to the BH line via the MAC layer and the relay layer of SN # 1. It is transmitted from the wireless port to the downstream BH line.

The downlink signal transmitted by SN # 1 to the downstream BH line is received by the wireless port for the BH line in SN # 5, which is the next hop, and is wireless for the access line via the MAC layer of SN # 5. It is transmitted from the port to the terminal device 7. The downlink signal transmitted from the BH line to the access line may not pass through the relay layer.

The uplink signal is transmitted to the backbone network 5 from the terminal device 7 via SN # 5, SN # 1, and CN # 0 along the path opposite to the path of the downlink signal described above.

<Configuration example of node 3>
(Example of hardware configuration of node 3)
Next, a hardware configuration example of the node 3 will be described with reference to FIG. The configuration example illustrated in FIG. 3 may be common to CN3 and SN3. As illustrated in FIG. 3, the node 3 includes, for example, a processor 31, a memory 32, a storage 33, an input / output (I / O) device 34, wireless IFs 35 and 36, a wired IF 37, a wired IF 39, and a bus 38. Good.

Note that in the hardware configuration example illustrated in FIG. 3, the hardware may be increased or decreased as appropriate. For example, addition or deletion of an arbitrary hardware block, division, integration in an arbitrary combination, addition or deletion of the bus 38, and the like may be performed as appropriate.

The wireless IF 35, the wireless IF 36, and the wired IF 37 (or the wired IF 39) may be regarded as corresponding to the two wireless ports (PHY ports) and one wired port illustrated in the protocol stack of FIG. .

The processor 31, the memory 32, the storage 33, the input / output device 34, the wireless IFs 35 and 36, and the wired IFs 37 and 39 are connected to the bus 38 and can communicate with each other, for example. The number of buses 38 may be one or plural.

A plurality of processors 31 may be provided in the node 3. Further, the processing in the node 3 may be executed by one processor 31 or may be executed by a plurality of processors 31. In one or a plurality of processors 31, a plurality of processes may be executed simultaneously, in parallel, or sequentially, or may be executed by other methods. The processor 31 may be a single core processor or a multi-core processor. The processor 31 may be implemented using one or more chips.

The one or more functions of the node 3 are realized by, for example, reading predetermined software into hardware such as the processor 31 and the memory 32. Note that “software” may be interchanged with other terms such as “program”, “application”, “engine”, or “software module”.

For example, the processor 31 reads and executes a program by controlling one or both of reading and writing of data stored in one or both of the memory 32 and the storage 33. Note that the program may be provided to the node 3 by communication via an electric communication line using at least one of the wireless IF 35, the wireless IF 36, and the wired IF 37, for example.

The program may be a program that causes a computer to execute all or part of the processing in the node 3. One or more functions of the node 3 are realized according to the execution of the program code included in the program. All or a part of the program code may be stored in the memory 32 or the storage 33, or may be described as a part of the operating system (OS).

For example, the program may include a program code that implements a functional block described later with reference to FIGS. 4 and 5, and a program code that executes any one or more of the flowcharts described later with reference to FIGS. 6 and 12 to 15. May be included. A program including such a program code may be referred to as a “wireless routing control program” for convenience.

The processor 31 is an example of a processing unit, and controls the entire computer by operating an OS, for example. The processor 31 may be configured using a central processing unit (CPU) including a peripheral device interface, a control device, an arithmetic device, a register, and the like.

Further, for example, the processor 31 reads out one or both of a program and data from the storage 33 to the memory 32 and executes various processes.

The memory 32 is an example of a computer-readable recording medium, and may be configured using at least one of ROM, EPROM, EEPROM, RAM, SSD, and the like, for example. “ROM” is an abbreviation for “Read Only Memory”, and “EPROM” is an abbreviation for “Erasable Programmable ROM”. “EEPROM” is an abbreviation of “Electrically Erasable Programmable ROM”, “RAM” is an abbreviation of “Random Access Memory”, and “SSD” is an abbreviation of “Solid State Drive”.

The memory 32 may be called a register, a cache, a main memory, a work memory, or a main storage device.

The storage 33 is an example of a computer-readable recording medium, such as an optical disc such as a CD-ROM (Compact Disc ROM), a hard disk drive (HDD), a flexible disc, a magneto-optical disc (for example, a compact disc, a digital versatile disc, (Blu-ray (registered trademark) disk), smart card, flash memory (for example, card, stick, key drive), flexible disk, magnetic strip, and the like. The storage 33 may be called an auxiliary storage device. The above-described recording medium may be, for example, a database including one or both of the memory 32 and the storage 33, a server, and other suitable media.

The input / output (I / O) device 34 is an example of an input device that receives a signal input from the outside of the node 3 and an output device that outputs a signal from the node 3 to the outside. Input devices may illustratively include one or more of a keyboard, mouse, microphone, switch, button, and sensor. The output device may illustratively include one or more of a light emitting device such as a display, a speaker, and an LED (Light Emitting Diode).

The button may include, for example, a power button and / or a reset button. The power button is operated for starting and shutting down the node 3, for example. The reset (or reroute) button is operated, for example, to indicate an intentional reset and / or rebuild (or reroute) of the tree path.

The input / output device 34 may be configured separately for input and output. Further, the input / output device 34 may have a configuration in which input and output are integrated, such as a touch panel display.

The wireless IF 35 exemplarily transmits and receives a wireless signal on the access line with the terminal device 7. The wireless IF 35 may include, for example, one or more antennas 350, a baseband (BB) signal processing circuit, a MAC processing circuit, an up converter, a down converter, and an amplifier (not shown).

The BB signal processing circuit of the wireless IF 35 illustratively includes an encoding circuit and a modulation circuit for encoding and modulating a transmission signal, and a demodulation circuit and a decoding circuit for demodulating and decoding a reception signal. It's okay.

The wireless IF 36 performs transmission / reception of a wireless signal on a BH line with another SN 3 exemplarily. Similarly to the wireless IF 35, the wireless IF 36 may include one or more antennas 360, a BB signal processing circuit, a MAC processing circuit, an up converter, a down converter, and an amplifier that are not shown.

The BB signal processing circuit of the wireless IF 36 includes, for example, an encoding circuit and a modulation circuit for encoding and modulating a transmission signal, and a demodulation circuit and a decoding circuit for demodulating and decoding a reception signal. It's okay.

The antenna 350 of the wireless IF 35 and the antenna 360 of the wireless IF 36 may be referred to as “access line antenna 350” and “BH line antenna 360”, respectively. One or both of the access line antenna 350 and the BH line antenna 360 may be an omnidirectional omni antenna or an antenna array in which directivity can be controlled. Beam forming may be performed by an antenna array having a plurality of directional antennas.

The plurality of directional antennas may be arranged in different directions, for example. For example, six directional antennas may be arranged so as to be shifted by 60 degrees. When forming a mesh link to be described later in the BH network 9, if there are a plurality of antennas that can communicate with the other node 3 of the communication partner in the node 3, the communication quality (for example, gain or power) is the best. It is also possible to link up with another node 3 using the indicated antenna and continue using the antenna even in the communication of the tree path after the link up. However, the antenna used for link-up may be different from the antenna used for tree path communication after link-up.

The wired IF 37 exemplarily transmits / receives a wired signal to / from the backbone network 5 and / or the upstream node 3. In addition, the wired IF 39 exemplarily transmits and receives a signal with a wire between the terminal device 7 and / or the downstream node 3. For the wired IFs 37 and 39, for example, a network interface conforming to the Ethernet (registered trademark) standard may be used. The wired IFs 37 and 39 may be provided at least in the CN3 and may not be provided in the SN3 (in other words, the SN3 may be optional). However, when a part of the BH line is wired, the wired IFs 37 and 39 may be used for the wired connection.

The node 3 may be configured to include hardware such as a microprocessor, a DSP, an ASIC, a PLD, and an FPGA. For example, the processor 31 may be implemented including at least one of these hardware. Some or all of the functional blocks described later with reference to FIGS. 4 and 5 may be realized by the hardware.

“DSP” is an abbreviation for “Digital Signal Processor”, and “ASIC” is an abbreviation for “Application Specific Integrated Circuit”. “PLD” is an abbreviation for “Programmable Logic Device”, and “FPGA” is an abbreviation for “Field Programmable Gate Array”.

(Example of functional configuration of node 3)
Next, a functional configuration example of the node 3 will be described with reference to FIGS. 4 and 5. FIG. 4 is a block diagram illustrating a functional configuration example of the node 3 according to the first embodiment, and FIG. 5 is a block diagram illustrating a functional configuration example of the control unit illustrated in FIG. 4.

As shown in FIG. 4, when focusing on the functional configuration, the node 3 has a wireless communication unit 301 for a wireless access line, a wireless communication unit 302 for a wireless BH line, a wired communication unit 303, a control unit 304, and The storage unit 305 may be provided.

The wireless communication unit 301 for the wireless access line is a functional block including the wireless IF 35 and the access line antenna 350 illustrated in FIG. The wireless communication unit 302 for the wireless BH line is a functional block including the wireless IF 36 and the BH line antenna 360 illustrated in FIG.

The wired communication unit 303 is a functional block including the wired IFs 37 and 39 illustrated in FIG. The storage unit 305 is a functional block including one or both of the memory 32 and the storage 33 illustrated in FIG.

The wireless communication unit 301 includes, for example, a transmission unit that transmits a control signal and / or a data signal addressed to the terminal device 7, and a reception unit that receives a control signal and / or a data signal transmitted by the terminal device 7. Good.

The wireless communication unit 302, for example, transmits a control signal and / or a data signal to a BH line linked up with another node 3, and a control signal and / or a data signal from the linked up wireless link. And a receiving unit for receiving.

The wired communication unit 303 may include, for example, a transmission unit that transmits control signals and / or data signals to the backbone network 5 and a reception unit that receives control signals and / or data signals from the backbone network 5.

The control unit 304 comprehensively controls the operation of the node 3. For example, the control unit 304 gives a control signal to any one or more of the wireless communication unit 301, the wireless communication unit 302, and the wired communication unit 303, so that the wireless access line, the wireless BH line, and the wired line Control communication via any one or more.

The control unit 304 is implemented by, for example, the processor 31 illustrated in FIG. 3 reading a program stored in the storage unit 305 and executing the read program.

The storage unit 305 stores, for example, the above-described node identification information and a route metric described later. As will be described later, when the transmission power value of the transmission source node 3 is not included in the path construction packet, the transmission power value of the transmission source node 3 may be stored in the storage unit 305.

(Configuration example of control unit 304)
As illustrated in FIG. 5, the control unit 304 may include a scan processing unit 341, a node management unit 342, a tree path control unit 343, and an IPT control unit 344, for example.

The scan processing unit 341 scans and discovers the presence of another node 3 located around (near) the node 3 in response to the activation of the node 3, for example. The scan may be a passive scan or an active scan. Taking the passive scan as an example, the scan processing unit 341 generates a beacon signal and transmits it to the surrounding area through the wireless communication unit 302.

Note that the node 3 existing at a position where the beacon signal can be received is referred to as a “neighboring node 3” or a “neighboring node 3”.

For example, the beacon signal includes information that explicitly or implicitly indicates an SSID (Service Set Identifier) or BSSID (Basic SSID), a beacon signal transmission period, and a usable channel (frequency). It's okay. For convenience, these pieces of information may be referred to as “BSS (Basic Service Set) related information.

In the case of active scanning, a probe request signal may be generated in the scan processing unit 341 and transmitted to the surrounding area through the wireless communication unit 302. The probe request signal is used, for example, to prompt the peripheral node 3 to transmit a beacon signal. An active scan may be performed when a beacon signal is not received within a certain time in a passive scan.

For example, the node management unit 342 stores, in the storage unit 305, information on the peripheral node 3 discovered by the scan by the scan processing unit 341 (for example, node identification information and BSS related information). In each node 3, information on the peripheral node 3 (hereinafter, sometimes referred to as “peripheral node information”) is stored in the storage unit 305, so that a plurality of nodes 3 are connected in the BH network 9 as will be described later. A mesh link linked in a mesh shape is constructed by the wireless links.

“Mesh link is established” may mean that a plurality of available wireless links are established or linked up between nodes 3 located in an area where wireless communication is possible with each other. Good. Therefore, the peripheral node information may be regarded as indicating information on a radio link that can be used between the nodes 3. “Radio link information” may be abbreviated as “link information” for convenience.

The tree path control unit 343 controls the construction and update of the tree path on the mesh link by transmitting a path control packet on the mesh link. For the construction and update of the tree path, for example, as will be described later, out of a plurality of radio links forming a mesh link, information on a radio link registered in the tree path (or excluded from the tree path) is selected (or the selection is performed). (Cancel).

“Registering” a wireless link in the tree path may be regarded as “selecting”, “validating”, “activating”, or “enabling” the link information registered in the tree path. Excluding a registered wireless link from the tree path is considered as “deselecting”, “invalidating”, “deactivating”, or “disabling” the link information registered in the tree path. Also good.

The IPT control unit 344 controls the packet transmission timing by the wireless communication unit 302 for the BH line, for example, according to the transmission cycle corresponding to the frequency reuse interval.

(Configuration Example of Tree Path Control Unit 343)
As illustrated in FIG. 5, the tree route control unit 343 may include, for example, a route control packet generation unit 3431, a route metric calculation unit 3432, and a tree route update unit 3433.

The route control packet generator 3431 generates a route control packet. The route control packet is an example of a control signal that is generated in the CN 3 in the BH network 9 and propagates to each node 3 starting from the CN 3.

For example, CN3 floods a control signal to each of the radio links linked up in CN3. When SN3 receives a control signal from any of the radio links linked up in SN3, SN3 floods the control signal to each of the radio links linked up in SN3. As described above, the control signal transmitted from the CN 3 propagates or transmits the mesh link sequentially or sequentially.

The CN 3 waits for the event while maintaining the link-up state of the radio link until an event that triggers transmission of the control signal occurs. The event will be described later with reference to FIG. When an event occurs, CN3 transmits a control signal using a radio link in which the link-up state is maintained.

Similarly, SN3 waits for the arrival (reception) of the control signal while maintaining the link-up state of the wireless link with CN3 or other SN3. Then, when a control signal is received from the radio link in the link up state, the control signal is transmitted to another radio link in which the link up state is maintained.

Note that CN3 and SN3 wait for the occurrence of an event and / or reception of a control signal (for example, a path construction packet) while maintaining the link-up state of the wireless link forming the mesh link even after the construction of the tree path. It's okay.

SN3 may add information to be transmitted to another SN3 to a control signal transmitted to another radio link in which the link-up state is maintained. A non-limiting example of information added to the control signal is a route metric calculated by the route metric calculation unit 3432. Further, among the wireless links that are linked up in SN3, SN3 may exclude the wireless link that has received the control signal from the control signal transmission destination candidates. Thereby, it can suppress that a control signal is transmitted to a mesh link unnecessarily or redundantly.

For example, the route control packet may include a route construction packet and a reset packet. These packet types may be identified by, for example, the type value of the packet header.

The route construction packet is, for example, a packet transmitted when constructing or updating a tree route. The route construction packet may include cumulatively the route metrics calculated in each of the nodes 3 through which the route construction packet has propagated. For example, the node 3 may transmit the path metric including the path metric from the core node to the node immediately before the self node.

The SN 3 that has received the path construction packet selects radio link information to be registered in the tree path from among the radio links that form a mesh link and can be used with the neighboring nodes 3 based on the cumulative path metric. .

The reset packet is, for example, a packet that is transmitted when CN 3 requests SN 3 to clear the tree path constructed in the mesh link. The SN 3 that has received the reset packet cancels the selection of the information on the radio link selected for the tree path.

The route metric calculation unit 3432 calculates, for example, a propagation quality indicator of a radio link with the peripheral node 3 that is a transmission source of the received route construction packet, and the route metric included in the received route construction packet includes A new path metric is obtained by adding the calculation result.

For example, RSSI (Received Signal Signal Strength Indicator) may be used as the propagation quality indicator of the radio link between the nodes 3. For example, a series of values obtained by uniformly sampling RSSI between nodes 3 at a constant time interval is represented as Rn (n is an integer of 1 or more), and the RSSI sequential average (series) An [dB] is expressed by the following equation (1). Ask for. Note that equation (1) is merely an example, and the RSSI sequential average may be obtained using another equation.

The sequential average An represented by the equation (1) converges to the average value of the stochastic process as the value of “n” increases. If “n” represents, for example, the number of transmissions (or the number of receptions) of the route construction packet after the transmission (or reception) of the reset packet, the RSSI sequential average between the nodes 3 according to the increase in the number n. An converges to a constant value. Therefore, the tree path constructed by transmitting the path construction packet converges asymptotically to a stable path.

Further, the route metric calculation unit 3432 uses, for example, the radio wave propagation loss (“path loss”) of the wireless link with the transmission source node 3 of the route construction packet using the RSSI sequential average An calculated by the equation (1). [DB] may be calculated by the following equation (2).

In Expression (2), “TXPower” represents the transmission power of the source node 3 of the path construction packet. The transmission power value of the transmission source node 3 may be stored in advance in, for example, the storage unit 305 as a known value in each node 3, or may be included in the path construction packet in the transmission source node 3.

Then, the route metric calculation unit 3432 obtains a new route metric by adding the path loss calculated by Expression (2) to the cumulative route metric included in the received route construction packet.

Therefore, the path metric represents the sum of the path loss of the radio link between CN3 and one or more SN3. The route metric calculated every time the route construction packet is received is stored in the storage unit 305, for example. The path metric stored in the storage unit 305 may be initialized to a maximum value, for example, by receiving a reset packet.

For example, when the new route metric calculated by the route metric calculation unit 3432 is smaller than the old route metric, the tree route update unit 3433 sets the upstream wireless link corresponding to the new route metric in the peripheral node information as an effective tree route. Select

For example, in SN3, when a route construction packet is received from each of different routes, the route metric of one or more wireless links propagated by each of the route construction packets is calculated by the route metric calculation unit 3432 separately for different routes. Is done.

Based on the path metric calculated separately for different paths, the tree path update unit 3433 selects a radio link corresponding to one of the different paths that received the path construction packet from the radio links linked up in the SN. Select the route to be used for transmission.

Since the tree path constructed in the mesh link has a tree structure, there is always one upstream node 3 for each SN3. Therefore, the tree path update unit 3433 selects, for example, a radio link (link information) with the upstream node 3 in the mesh link as a radio link registered in the tree path, or cancels the selection. A route can be constructed or updated.

Therefore, the tree path update unit 3433 is an example of a selection unit that selects one of the radio links linked up in SN3 as a tree path, and is also an example of a cancellation unit that cancels the selection.

As described above, when each of the SNs 3 selects a radio link with the upstream node 3, one of the radio links that are linked up in the SN 3 (form a mesh link) is transmitted to the data signal. It may be understood that this corresponds to selecting a transmission path.

Alternatively, each of the SNs 3 selects a radio link between the upstream node 3 and at least a part of a plurality of radio links linked up between the plurality of nodes 3 to a specific node (eg, CN3). It may be understood that this corresponds to selecting an element (element or component) of a radio link set that forms a tree path having as a vertex.

In each SN 3, selection and cancellation of a radio link (in other words, update of a radio link selected as a tree path) is performed according to a change in path metric calculated every time a path construction packet is received. Therefore, the update frequency of the tree path can be changed by changing the number of transmissions per unit time of the path construction packet by CN3.

For example, as the radio wave propagation environment of the BH network 9 is more likely to change, the follow-up performance to the radio wave propagation environment change of the BH network 9 can be improved by increasing the number of times the route construction packet is transmitted by the CN 3 per unit time. it can.

Note that the radio link with the downstream node 3 can be grasped by, for example, an acknowledgment (ACK) signal received from the downstream node 3 after the downstream path is established. For example, when the downstream node 3 updates the route metric by receiving the route construction packet, the downstream node 3 transmits (unicasts) the ACK signal to the parent node 3 that is the transmission source of the route construction packet. The ACK signal to be unicast may include, for example, information on a radio link in a link-up state that is stored and managed in the downstream node 3 that is the transmission source of the ACK signal. The parent node 3 can determine the downlink radio link to be selected and registered in the tree path by receiving the ACK signal from the downstream node 3.

<Operation example>
Hereinafter, an operation example of the above-described wireless communication system 1 will be described.

(Link setup procedure)
FIG. 6 is a flowchart illustrating an example of a link setup procedure between the nodes 3 according to the first embodiment (in other words, a wireless BH line in the BH network 9).

As illustrated in FIG. 6, in the BH network 9, each of the nodes 3 including the CN and the SN 3 is a node existing in the vicinity (hereinafter, may be referred to as a “peripheral node”) 3 in accordance with, for example, the IBSS mode. Is scanned (S11).

“IBSS” is an abbreviation for “Independent Basic Service Set”. The IBSS mode may be referred to as an ad hoc mode. “Startup” of the node 3 may include power-on of the node 3 and restart by resetting the node 3.

For example, in the scanning process S11, each of the nodes 3 starts transmitting a beacon signal to the peripheral area in response to the activation. For example, the beacon signal is generated in the scan processing unit 341 of the control unit 304 and transmitted from the BH line antenna 360 (wireless communication unit 302).

In the scan processing S11 in the IBSS mode, in order to avoid collision between beacon signals, each of the activated nodes 3 transmits a beacon signal alternately (for example, at a timing managed in a pseudo-random manner in the node 3). You can do it.

The node 3 that has received the beacon signal transmitted by the other node 3 stores the information included in the received beacon signal, for example, in the storage unit 305 (S12). The transmission / reception of the beacon signal may be performed for each channel (in other words, an available channel) on which the node 3 operates.

Therefore, the scan process (S11) may be referred to as “channel scan”. Note that the node 3 that has received the beacon signal may stop transmitting the beacon signal for the channel that has received the beacon signal.

Each node 3 stores the BSS related information included in the beacon signal that can be received from the other nodes 3, so that information on the peripheral nodes 3 that can communicate with each other by wireless links (hereinafter referred to as “peripheral node information”). Can manage).

As each node 3 stores and manages the peripheral node information, for example, as shown in FIG. 7, an available radio link (which may be read as “channel”) is managed in each node 3. Thereby, the link setup of the wireless BH line is completed, and the mesh link is linked up in the BH network 9.

FIG. 8 shows an example of peripheral node information managed in each of the nodes # 0 to # 7 illustrated in FIG.

In FIG. 8A, node IDs # 1 to # 3 are stored and managed in node (CN) # 0, and CN # 0 can use radio links with SNs # 1 to # 3, respectively. Indicates that it is in a state.

In FIG. 8B, in SN # 1, node IDs # 0, # 2, # 4, and # 5 are stored and managed, and SN # 1 is stored in nodes # 0, # 2, # 4, and # 5, respectively. It indicates that the wireless link between and can be used.

(C) in FIG. 8 shows that node IDs # 0, # 1, # 3, # 5, and # 7 are stored and managed in SN # 2, and SN # 2 is stored in nodes # 0, # 1, # 3, It shows that the wireless link between # 5 and # 7 can be used.

In FIG. 8D, node IDs # 0 and # 2 are stored and managed in SN # 3, and SN # 3 is in a state in which a radio link between nodes # 0 and # 2 can be used. It shows that.

(E) in FIG. 8 shows that node IDs # 1, # 5, and # 6 are stored and managed in SN # 4, and the wireless communication between SN # 4 and nodes # 1, # 5, and # 6 is performed. Indicates that the link is available.

(F) in FIG. 8 shows that node IDs # 1, # 2, # 4, # 6, and # 7 are stored and managed in SN # 5, and SN # 5 has nodes # 1, # 2, # 4, It shows that the wireless link between # 6 and # 7 can be used.

In FIG. 8G, the node IDs # 4 and # 5 are stored and managed in the SN # 6, and the SN # 6 is in a state where the wireless links between the nodes # 4 and # 5 can be used. It shows that.

(H) of FIG. 8 is in a state where the node IDs # 2 and # 5 are stored and managed in the SN # 7, and the SN # 7 can use the radio links between the nodes # 2 and # 5, respectively. It shows that.

As described above, a mesh-like wireless link using the IBSS mode is formed (or constructed) between the nodes 3. A mesh-like wireless link constructed using the IBSS mode as described above may be referred to as an IBSS mesh link.

(Tree path control over IBSS mesh link)
Next, tree path control on the IBSS mesh link will be described.
FIG. 9 is a diagram illustrating an example of tree path control on the IBSS mesh link according to the first embodiment.

In FIG. 9A, in the IBSS mesh link illustrated in FIG. 7, a tree topology indicated by a thick solid line is represented by CN # 0, SN # 1, SN # 4, SN # 5, and SN # 6. An example constructed by tree path control is shown.

In FIG. 9B, in the IBSS mesh link illustrated in FIG. 7, the tree topology indicated by the thick solid line by CN # 0, SN # 1, SN # 5, and SN # 6 is changed by tree path control. An example to be constructed is shown.

FIG. 9 may be taken to show that the tree topology implemented at different times shows the tree topology changing over time between (A) and (B) on the IBSS mesh link. .

Here, in the tree path control as illustrated in FIG. 9, since the IBSS mesh link is already linked up, for example, in the peripheral node information illustrated in FIG. This can be realized by selecting information.

As a non-limiting example, FIGS. 10 and 11 show examples of selecting link information in each of CN # 0 and SN # 1 to # 7 corresponding to each of the tree paths illustrated in FIG. 10 and 11, information indicated by hatching corresponds to the link information selected for the tree path. The information shown in FIGS. 10 and 11A to 11H corresponds to the information illustrated in FIGS. 8A to 8H, respectively.

For example, in the tree path shown in FIG. 9A, the link information indicated by hatching in FIGS. 10A, 10B, 10E, and 10F is the nodes # 0, #, respectively. It is constructed by being selected in 1, # 4, # 5 and # 6.

On the other hand, in the tree path shown in FIG. 9B, the link information indicated by hatching in FIGS. 11A, 11B, and 11F is the nodes # 0, # 1, and # 5, respectively. And # 6 are selected.

Note that the selection of link information is performed by the control unit 304 (for example, the tree route update unit 3433 of the tree route control unit 343).

As described above, in the mesh link that is linked up in advance between the nodes 3, the link information selected by each node 3 based on the path metric is changed (or switched), thereby constructing and updating the tree path. Can be speeded up. In other words, it is possible to improve the follow-up performance with respect to the change of the tree path according to the time change of the path metric.

For example, every time the tree path changes, it is not necessary to perform processing (for example, several seconds) related to association and / or authentication between the nodes 3, so that the tracking performance with respect to the time change of the tree path is not necessary. Can be improved.

Here, “time change of route metric” is caused by “time change of wireless environment” in the BH network 9, in other words, “time change of BH channel quality”. Therefore, in the “adaptive tree path control” of the present embodiment, it is possible to improve the follow-up performance with respect to the time change of the BH channel quality. Therefore, it is possible to suppress the occurrence of communication disconnection due to the change of the tree path in the wireless BH line, and it is easy to realize uninterrupted communication.

(Operation example of CN)
FIG. 12 is a flowchart illustrating an operation example of the CN 3 including tree path control on the IBSS mesh link according to the first embodiment. The flowchart of FIG. 12 may be understood as being executed by the control unit 304 (for example, the tree path control unit 343) of the CN3.

As shown in FIG. 12, the control unit 304 of the CN 3 monitors, for example, whether or not a specific event is detected (S31; NO). The “specific event” may include, for example, that the CN 3 has been activated, that the reset button has been operated, and that a specific timing has arrived. An example of “specific timing” is, for example, transmission timing set to transmit a route control packet regularly or irregularly.

The transmission cycle when the path control packet is periodically transmitted may be constant, and the tree path constructed in the present embodiment is asymptotically stable, so that it depends on the number of times the flowchart of FIG. 12 is executed. It may be changed. Further, for example, the predetermined time may be set to “specific timing” so that the tree path is updated according to a time zone such as a weekend or a nighttime and daytime in a day.

When a specific event is detected (S31; YES), the control unit 304 of the CN 3 generates a route control packet, and passes the route control packet to the peripheral SN 3 identified based on the peripheral node information through the wireless communication unit 302, for example. Is transmitted (broadcast) (S32).

For example, when the activation of CN3 is detected and when the transmission timing of the route construction packet is detected, the route construction packet is transmitted to the peripheral SN3. When the operation of the reset button is detected and when the transmission timing of the reset packet is detected, the reset packet is transmitted to the peripheral SN3.

After transmitting the route control packet, the control unit 304 monitors, for example, whether or not a predetermined time has passed (timeout) (S33). When the timeout is not detected (S33; NO), the control unit 304 may shift the process to S31.

On the other hand, when the elapse of a certain time is detected (S33; YES), the control unit 304 may start transmitting a data packet (S34). The data packet is transmitted according to the IPT, as will be described later with reference to FIGS. 14 and 15, for example.

As described above, the CN 3 transmits (broadcasts) a route control packet to each of a plurality of wireless links that are linked up with the peripheral node 3, so that the route control packet is transmitted to each SN 3 that configures the BH network 9. Is propagated. Thereby, in the BH network 9 in which the mesh link is linked up, it is possible to speed up the construction and update of the tree path based on the path metric. Therefore, it is possible to improve the follow-up performance with respect to the change of the tree path according to the time change of the path metric.

(Operation example of SN)
Next, an operation example of SN3 will be described with reference to FIG. FIG. 13 is a flowchart showing an operation example of SN3 including tree path control on the IBSS mesh link according to the first embodiment. The flowchart of FIG. 13 may be understood as being executed by the control unit 304 (for example, the tree path control unit 343) of SN3.

SN3 monitors, for example, whether the wireless communication unit 302 receives a route control packet (S51; NO).

When reception of a route control packet is detected (S51; YES), the SN3 control unit 304 confirms the type of the route control packet. For example, the control unit 304 confirms whether the received route control packet is a reset packet or a route construction packet (S52 and S54).

When the received route control packet is a reset packet (S52; YES), the control unit 304 performs an initialization process (S53). The initialization process may include the following process, for example.
-Deselecting a link selected as a valid tree route in the peripheral node information-Initializing a stored route metric to an initial value (for example, maximum value)

After the initialization processing, for example, the control unit 304 transmits (floods) the received reset packet to the peripheral SN 3 (S53a). The reset packet may include an identifier (ID). Each of the nodes 3 may store an ID included in the received reset packet.

When each of the nodes 3 indicates that the received ID of the reset packet matches the stored ID, in other words, when indicating that the reset packet has been transmitted (transferred) in the past, the further transmission of the reset packet is not performed. Not performed. Thereby, it is possible to prevent the reset packet from looping in the BH network 9.

On the other hand, when the received route control packet is not a reset packet (S52; NO), the control unit 304 confirms whether or not the route control packet is a route construction packet (S54).

When the received route control packet is a route construction packet (S54; YES), the control unit 304 refers to the peripheral node information (S55), and the propagation quality index (for example, radio wave propagation loss) of the link that has received the route construction packet. Is calculated (S56).

Based on the calculated radio wave propagation loss, the control unit 304 calculates a path metric (S57). For example, the control unit 304 calculates the cumulative radio wave propagation loss as a new path metric by adding the calculated radio wave propagation loss and the propagation quality index included in the received path construction packet.

Then, the control unit 304 compares the new route metric with the old route metric stored before the new route metric is calculated, and determines whether or not the route metric needs to be updated (S58).

For example, when the new route metric is smaller than the old route metric, the control unit 304 determines to update the old route metric to the new route metric (S58; YES). In response to the determination, the control unit 304 selects an upstream wireless link corresponding to the new route metric in the peripheral node information as a valid tree route (update of the selected link; S59).

In response to the update of the selected link, for example, the control unit 304 transmits (broadcasts) the route construction packet including the new route metric to the neighboring SN 3 identified in the neighboring node information (S60).

Thereafter, the control unit 304 monitors whether or not a predetermined time has elapsed (timeout) (S61). When the timeout is not detected (S61; NO), the control unit 304 may shift the process to the reception monitoring process (S51) of the route control packet. When a timeout is detected (S61; YES), the control unit 304 may start a data packet transmission process according to, for example, IPT (S62).

If the received route control packet is neither a reset packet nor a route construction packet (S52 and S54; NO), the control unit 304 may move the process to a route control packet reception monitoring process (S51).

Also, when the calculated new route metric is greater than or equal to the old route metric and it is determined that the selected link does not need to be updated (S58; NO), the control unit 304 moves the process to the route control packet reception monitoring process (S51). You may migrate.

As described above, the SN 3 selects one of a plurality of radio links linked up with the peripheral node 3 based on the path metric in response to reception of the path construction packet. Thereby, in the BH network 9 in which the mesh link is linked up, it is possible to speed up the construction and update of the tree path based on the path metric. Therefore, it is possible to improve the follow-up performance with respect to the change of the tree path according to the time change of the path metric.

(IPT in the tree path)
Next, with reference to FIG. 14 and FIG. 15, an operation example of the node 3 when a data packet is transmitted by IPT in the tree path constructed by the tree path control described above will be described.

The flowchart illustrated in FIG. 14 may be regarded as being executed in the process S34 of CN3 illustrated in FIG. 12, for example. On the other hand, the flowchart illustrated in FIG. 15 may be considered to be executed in, for example, the process S62 of SN3 illustrated in FIG. 14 and 15 are executed by the control unit 304 (for example, the IPT control unit 344) of CN3 and SN3, respectively.

(Operation example of CN)
As illustrated in FIG. 14, the CN 3 monitors, for example, whether there is a downlink packet in the transmission buffer (S81).

When there is a downstream packet in the transmission buffer (S81; YES), CN3 sets the timer TM to an initial value (for example, 0) (S82), and the packet is counted while the count value of the timer TM is less than the transmission cycle Ps. Waiting for transmission (S83; NO). On the other hand, when there is no downstream packet in the transmission buffer (S81; NO), the CN 3 may end the process related to packet transmission.

Note that the timer TM may be provided in the IPT control unit 344, for example. The transmission buffer is an example of a memory that temporarily stores a packet to be transmitted to the wireless BH line, and may be provided in the wireless communication unit 302 for the wireless BH line or may be embodied in the storage unit 305. . In any case, it is sufficient that the transmission buffer can be accessed by the control unit 304 and packets can be written and read by the access. These matters also apply to SN3.

If the count value of the timer TM is equal to or greater than the transmission cycle Ps (S83; YES), the downlink packet in the transmission buffer is transmitted from the wireless communication unit 302 (S84). When there are a plurality of downlink packets, the CN 3 may continuously transmit the plurality of downlink packets.

After transmitting the downlink packet, the CN 3 determines whether or not the transmission of the downlink packet is successful (S85). Whether or not the transmission of the packet is successful can be detected by whether or not an acknowledgment (ACK) signal is received within a predetermined time from the receiving party of the packet. In CN3, reception of an ACK signal may be determined as an event that indirectly (implicitly) indicates that the frequency reuse interval is satisfied.

When reception of the ACK signal for the downlink packet is not detected within a certain time (S85; NO), the CN 3 determines that the transmission cycle Ps is not appropriate (for example, too short) and increases the transmission cycle Ps by, for example, ΔPup. (S86). Note that detection of no reception of an ACK signal may include detection of reception of a negative acknowledgment (NACK) signal.

Thereafter, the CN 3 determines whether or not a specified time for which packet transmission is allowed has elapsed (whether or not a transmission timeout has been detected) (S87). When the transmission timeout is not detected (S87; NO), the CN 3 may retransmit the downlink packet that has not received the ACK signal in the process S84.

On the other hand, when a transmission timeout is detected (S87; YES), the CN 3 discards the packet that could not receive the ACK signal, returns the process to S81, and monitors the presence or absence of the downlink packet.

If the downlink packet has been successfully transmitted (S85; YES), the CN 3 determines that the transmission cycle Ps may be shortened, and decreases the transmission cycle Ps by, for example, ΔPdown (S88). Thereafter, the CN 3 returns the process to S81 and monitors the presence / absence of a downlink packet.

As described above, the transmission cycle Ps according to the appropriate frequency reuse interval is set in the CN 3 by dynamically adjusting the transmission cycle Ps according to whether or not the transmission of the downlink packet is successful.

In the above example, the transmission cycle Ps is variable, but the transmission cycle Ps may be a fixed value. In other words, it is optional that the transmission period Ps is variable. For example, in FIG. 14, the processes indicated by S86 and S88 may be omitted.

Further, the value of the transmission cycle Ps may be set to “0”. For example, in a network with a low number of hops, such as several hops, a packet collision avoidance function of layer 2 or lower such as CSMA / CA (Carrier Sense Multiple Access / Collision Avoidance) is effective without using special packet transmission control. Packet transmission is possible. Therefore, for example, when each node 3 has a layer 2 or lower packet collision avoidance function such as CSMA / CA, “Ps = 0” may be set.

(Operation example of SN)
As illustrated in FIG. 15, the SN 3 monitors, for example, whether a route control packet is received (S90). Note that the flowchart of FIG. 15 may be common to packet transmission processing to the downlink and uplink.

When the route control packet is received (S90; YES), SN3 shifts the process to the process S52 of FIG. On the other hand, when reception of a route control packet is not detected (S90; NO), SN3 monitors whether a data packet to be transmitted (relayed) to the downlink and / or uplink is received (S91).

When the data packet is received (S91; YES), SN3 transmits the received data packet from the wireless communication unit 302 (S92). When a plurality of data packets are received, the SN 3 may continuously transmit the received plurality of data packets.

After transmitting the data packet, the SN 3 determines whether or not the data packet has been successfully transmitted (S93). If reception of the ACK signal for the data packet is not detected within a certain time (S93; NO), SN3, for example, whether or not a specified time allowed to transmit the data packet has passed (whether or not a transmission timeout has been detected). (S94). When the transmission timeout is not detected (S94; NO), the SN 3 may retransmit the data packet that has not received the ACK signal in the process S92.

On the other hand, when a transmission timeout is detected (S94; YES), SN3 discards the data packet that has not received the ACK signal, returns the process to S91, and waits (monitors) reception of the data packet to be relayed. .

If the transmission of the data packet is successful (S93; YES), the SN 3 returns the process to S91 and waits for (monitors) reception of the data packet to be relayed.

Note that if reception of a data packet is not detected in the process S91, the SN 3 may end the process. Alternatively, when the reception of the data packet is not detected in the process S91, the SN 3 may return the process to the process S90.

By combining the “adaptive tree path control” and “IPT control” described above, data packets are transmitted and received in a time-sharing manner with a period corresponding to the frequency reuse interval in the tree path that changes following the change in the wireless environment adaptively. The

Therefore, it is possible to realize adaptive time division multiple access (TDMA) or time division duplex (TDD) with high tracking performance with respect to changes in the quality of the wireless BH line.

(Second Embodiment)
In the first embodiment, the example in which the IBSS mesh link as illustrated in FIG. 7 is formed using the IBSS mode of the node 3 has been described. However, there may be a case where the node 3 does not support the IBSS mode.

When the node 3 does not support the IBSS mode, for example, a mesh link equivalent to the IBSS mesh link illustrated in FIG. 7 is constructed by combining the AP (Access Point) mode and the STA (Station) mode. Is possible.

FIG. 16 shows an example in which a mesh link is constructed between nodes 3 using a combination of AP mode and STA mode (may be referred to as “hybrid”). The combination of the AP mode and the STA mode is referred to as “pseudo IBSS mode” for convenience.

16A to 16C exemplarily show three nodes A, B, and C. FIG. 17 shows an example of a radio link setup procedure using the pseudo IBSS mode between the nodes A and B and between the nodes A and C together with the protocol stacks of the nodes A to C. .

For example, as shown in FIG. 16A, the node A transmits a beacon signal to the surroundings according to the operation of the AP (mode) in response to the activation. Each of the peripheral nodes B and C that have received the beacon signal transmits an association request to the node A according to the operation of the STA (mode).

When the node A permits the association requests received from the peripheral nodes B and C, the node A transmits an association response to the peripheral nodes B and C according to the operation of the AP. As a result, multipoint (nodes B and C) radio links starting from node A (AP) are linked up.

Similarly, as shown in FIG. 16B, for example, the node B transmits a beacon signal to the surroundings according to the operation of the AP (mode) in response to the activation. Each of the peripheral nodes A and C that have received the beacon signal transmits an association request to the node B according to the operation of the STA (mode). As a result, multi-point (nodes A and C) radio links starting from node B are linked up.

Focusing on node C, as shown in FIG. 16C, node C transmits a beacon signal to the surroundings according to the operation of the AP (mode) in response to activation. Each of the peripheral nodes A and B that have received the beacon signal transmits an association request to the node C according to the operation of the STA (mode). As a result, the multipoint (nodes A and B) radio links starting from the node C (AP) are linked up.

To summarize the above operation example, each of the nodes A, B and C operates in the AP mode as a transmission source of the beacon signal, while when receiving a beacon signal transmission source from other peripheral nodes, Operates in STA mode in relation to peripheral nodes.

FIG. 17 schematically shows the above operation example together with the protocol stacks of the nodes A, B, and C, respectively. In FIG. 17, for convenience of explanation, the physical layer (L1) and the MAC layer (L2) in the same node 3 are visualized separately in the AP mode and the STA mode.

However, L1 and L2 may be common to the AP mode and the STA mode. For example, L1 and L2 may be realized by the same hardware, and AP mode and STA mode are applied to the same channel by using a multiplexing method such as time division, SDM (Space Division Division Multiplexing), or code division. The wireless communication related to and may be multiplexed. Processing or control in a hybrid mode (pseudo IBSS mode) of the AP mode and the STA mode may be included in the layer 2.5, for example.

In FIG. 17, when attention is paid to the node A, between the node A (AP mode) and the node B (STA mode) and the node C (STA mode) that have received the beacon signal transmitted from the node A, The association procedure illustrated in 16 (A) is executed.

Node A operates in the STA mode in relation to Node B by receiving a beacon signal whose source is Node B (AP mode). Therefore, the association procedure illustrated in FIG. 16B is executed between the node A (STA mode) and the node B (AP mode).

Similarly, the node A operates in the STA mode in relation to the node C by receiving the beacon signal whose transmission source is the node C (AP mode). For this reason, the association procedure illustrated in FIG. 16C is executed between the node A (STA mode) and the node C (AP mode).

For nodes B and C, as in node A, the association procedure illustrated in FIG. 16 is executed between other nodes according to the AP mode and the STA mode.

As described above, the radio links are linked up between the nodes A and B, the nodes B and C, and the nodes C and A, respectively. When a plurality of radio links of different channels are linked up, the plurality of radio links may be aggregated (or bonded) to one radio band.

FIG. 18 is a block diagram illustrating a functional configuration example of the control unit 304 according to the second embodiment. In FIG. 18, the same functional blocks as the functional blocks illustrated in FIG.

As illustrated in FIG. 18, the scan processing unit 341 of the control unit 304 includes, for example, a beacon transmission unit 3411, a request reception unit 3412, a response transmission unit 3413, a beacon reception unit 3414, a request transmission unit 3415, and a response reception unit. 3416 may be provided.

The beacon transmission unit 3411, the request reception unit 3412, and the response transmission unit 3413 operate according to the AP mode, for example. The request transmission unit 3415 and the response reception unit 3416 operate, for example, according to the STA mode.

First, the beacon transmission unit 3411, the request reception unit 3412, and the response transmission unit 3413 that operate according to the AP mode will be described.

The beacon transmission unit 3411 generates a beacon signal and transmits it to the surrounding area through the wireless communication unit 302. Of the peripheral nodes 3 existing in the peripheral area, the peripheral node 3 that has received the beacon signal transmits an association request to the node 3 that has transmitted the beacon signal.

The request reception unit 3412 receives the association request transmitted from the peripheral node 3.

When the request reception unit 3412 receives the association request transmitted from the peripheral node 3, the response transmission unit 3413 transmits an association response to the peripheral node 3 that has transmitted the association request. Thereby, the association between the nodes 3 is completed.

The node management unit 342 stores (registers) the peripheral node information of the peripheral node 3 that has transmitted the association request in the storage unit 305. In other words, the node management unit 342 receives the beacon signal transmitted by the beacon transmission unit 3411 and registers the peripheral node 3 that transmitted the association request in the storage unit 305 as node information that has been linked up.

The peripheral node information may be included in an association request transmitted by the peripheral node 3, for example. The node management unit 342 stores the peripheral node information included in the association request received by the request reception unit 3412, for example, in the storage unit 305.

Next, the beacon receiving unit 3414, the request transmitting unit 3415, and the response receiving unit 3416 that operate according to the STA mode will be described.

The beacon receiving unit 3414 receives a beacon signal transmitted from the peripheral node 3.

When the beacon receiving unit 3414 receives the beacon signal transmitted from the peripheral node 3, the request transmission unit 3415 transmits an association request to the peripheral node 3 that has transmitted the beacon signal. In other words, the request transmission unit 3415 transmits an association request to the peripheral node 3 that has transmitted the beacon signal so that the peripheral node 3 that has transmitted the beacon signal is registered as a link-up node. The peripheral node 3 that has received the association request (the peripheral node 3 that has transmitted the beacon signal) transmits an association response to the node 3 that has transmitted the association request.

The response receiving unit 3416 receives the association response transmitted from the peripheral node 3. Thereby, the association between the nodes 3 is completed.

A plurality of beacon receiving units 3414, request transmitting units 3415, and response receiving units 3416 may exist so as to cope with a plurality of beacon signals transmitted from a plurality of peripheral nodes 3. For example, a plurality of STA mode blocks surrounded by a dotted line in FIG. 18 may exist. Alternatively, each of the beacon receiving unit 3414, the request transmitting unit 3415, and the response receiving unit 3416 may be one, and each unit may deal with a plurality of beacon signals transmitted from a plurality of peripheral nodes 3. That is, as in the STA mode surrounded by the dotted line in FIG. 18, each unit may cope with a plurality of beacon signals transmitted from a plurality of peripheral nodes 3.

When the response reception unit 3416 receives the association response transmitted by the peripheral node 3 (in other words, the peripheral node 3 that transmitted the beacon signal) by the response reception unit 3416, the node management unit 342 stores the peripheral node information of the peripheral node 3 Store in 305. For example, the node management unit 342 stores the peripheral node information of the peripheral node 3 that has transmitted the association response in the storage unit 305 after transmitting the beacon signal. Note that the peripheral node information of the peripheral node 3 that has transmitted the association response after transmitting the beacon signal may be included in the beacon signal.

The tree path control unit 343 and the IPT control unit 344 may be the same as or similar to the tree path control unit 343 and the IPT control unit 344 described in FIG.

Each of the nodes 3 has the function shown in FIG. 18, and by storing and managing the peripheral node information, for example, as shown by the dotted line in FIG. 7, the available radio links are managed in the individual nodes 3. The For example, as shown in FIG. 8, peripheral node information is managed in the storage units 305 of the nodes # 0 to # 7.

FIG. 19 is a flowchart illustrating an example of a link setup procedure of the node 3 according to the second embodiment. Hereinafter, an example of a link setup procedure when the node # 1 of FIG. 7 operates according to the AP mode will be described.

Node # 1 repeatedly executes the processing of the flowchart shown in FIG. For example, the node # 1 may repeatedly execute the process of the flowchart shown in FIG. 19 at a cycle shorter than the cycle at which the tree path control is executed.

The beacon transmission unit 3411 of the node # 1 generates a beacon signal and transmits it to the peripheral area through the wireless communication unit 302 (S101). Note that the beacon signal transmitted by the node # 1 is received by the node # 0, the node # 2, the node # 4, and the node # 5 in the example of FIG. When the request transmission unit 3415 of each of the node # 0, the node # 2, the node # 4, and the node # 5 receives the beacon signal transmitted from the node # 1, the request transmission unit 3415 transmits an association request to the node # 1.

The request reception unit 3412 of the node # 1 receives the association request transmitted from the peripheral node 3 that has received the beacon signal transmitted in S101 (S102). For example, the request reception unit 3412 of the node # 1 receives an association request transmitted by the node # 0, the node # 2, the node # 4, and the node # 5 that has received the beacon signal of S101.

The request transmission unit 3415 of the node # 1 transmits an association response to the peripheral node 3 that has transmitted the association request received in S102 (S103). For example, the request transmission unit 3415 of the node # 1 transmits an association response to each of the node # 0, the node # 2, the node # 4, and the node # 5 that transmitted the association request.

The node management unit 342 of the node # 1 stores the peripheral node information of the peripheral node 3 that has transmitted the association request received in S102 in the storage unit 305 (S104). For example, the node management unit 342 of the node # 1 stores the peripheral node information of the node # 0, the node # 2, the node # 4, and the node # 5 that transmitted the association request in the storage unit 305. Thereby, the node # 0, the node # 2, the node # 4, and the node # 5 are registered (managed) as nodes that are linked up (may be referred to as link-up nodes) in the node # 1. Note that the peripheral node information of the node # 0, the node # 2, the node # 4, and the node # 5 may be included in the association request received in S102.

In the above description, the peripheral node information is included in the association request. However, the present invention is not limited to this. The peripheral node information may be transmitted from the peripheral node 3 to the node # 1 by a procedure different from the association procedure. For example, the peripheral node 3 may transmit the peripheral node information to the node # 1 after the node # 1 transmits the association response to the peripheral node 3 (S103) (after the association is completed).

In the above, node # 1 generates a beacon signal and transmits it to the peripheral area, and the peripheral node transmits a probe request according to the beacon. However, the present invention is not limited to this. For example, the peripheral node 3 may spontaneously transmit a probe request when the beacon from the node # 1 cannot be detected, and the node # 1 may receive the probe request and return a probe response to the peripheral node 3.

FIG. 20 is a flowchart illustrating an example of a link setup procedure of the node 3 according to the second embodiment. Hereinafter, an example of a link setup procedure when the node # 1 of FIG. 7 operates according to the STA mode will be described.

Node # 1 repeatedly executes the processing of the flowchart shown in FIG. For example, the node # 1 may execute the flowchart shown in FIG. 20 at a cycle shorter than the cycle in which the process of the flowchart described in FIG. 19 is executed.

The beacon receiving unit 3414 of the node # 1 receives the beacon signal transmitted from the peripheral node 3 (S111). For example, in FIG. 7, it is assumed that node # 2 operates according to the AP mode and transmits a beacon signal. In this case, the beacon receiving unit 3414 of the node # 1 receives the beacon signal transmitted by the node # 2.

In response to the reception of the beacon signal in S111, the request transmission unit 3415 of the node # 1 transmits an association request to the peripheral node 3 that transmitted the beacon signal (S112). For example, the request transmission unit 3415 of the node # 1 transmits an association request signal to the node # 2 that transmitted the beacon signal. The node # 2 that has received the association request transmits an association response to the node # 1 that has transmitted the association request.

The response receiving unit 3416 of the node # 1 receives the association response transmitted from the peripheral node 3 that transmitted the beacon signal (S113). For example, the response reception unit 3416 of the node # 1 receives an association response transmitted from the node # 2 that transmitted the beacon signal.

When the association response is received in S113, the node management unit 342 of the node # 1 stores the peripheral node information of the peripheral node 3 that transmitted the beacon signal (the peripheral node 3 that transmitted the beacon signal received in S111). It is stored in 305 (S114). For example, the node management unit 342 of the node # 1 stores the peripheral node information of the node # 2 that transmitted the beacon signal in the storage unit 305. As a result, node # 2 is registered (managed) as a linked-up node in node # 1. Note that the peripheral node information of the node # 2 may be included in the transmitted beacon signal.

Note that the beacon signal received by the node # 1 in S111 is also received by the node # 0, the node # 3, the node # 5, and the node # 7 in addition to the node # 1 in the example of FIG. Node # 0, node # 3, node # 5, and node # 7 that have received the beacon signal register node # 2 as a linked-up node by executing the same processing as node # 1.

In the above description, the peripheral node information is included in the beacon signal. However, the present invention is not limited to this. For example, the peripheral node information may be transmitted to the node # 1 by the peripheral node 3 that transmits the beacon signal after the node # 1 receives the association response (S113) (after the association is completed).

As described above, the beacon transmission unit 3411 of the node 3 transmits a beacon signal. The request receiving unit 3412 of the node 3 receives an association request transmitted from the peripheral node 3 that has received the beacon signal among the peripheral nodes 3. The response transmission unit 3413 of the node 3 transmits the association response to the peripheral node 3 that has transmitted the association request. In response to the transmission of the association response, the node management unit 342 of the node 3 stores information on the radio link between the transmission source of the beacon signal (node 3) and the transmission source of the association request (peripheral node 3). Managed by 305.

Further, the beacon receiving unit 3414 of the node 3 receives a beacon signal transmitted from the peripheral node 3. The request transmission unit 3415 of the node 3 transmits an association request to the peripheral node 3 that has transmitted the beacon signal. The response receiving unit 3416 of the node 3 receives an association response transmitted from the peripheral node 3 that transmitted the beacon signal. The node management unit 342 of the node 3 stores information on a radio link between the association request transmission source (node 3) and the beacon signal transmission source (peripheral node 3) in response to reception of the association response. Managed by 305.

Thereby, even if the node 3 does not support the IBSS mode, the mesh link illustrated in FIG. 7 can be constructed.

In addition, even when the node 3 does not support the IBSS mode, the follow-up performance with respect to the path change according to the fluctuation of the radio wave propagation quality between the nodes can be improved, and the occurrence of the communication interruption accompanying the path change can be suppressed.

DESCRIPTION OF SYMBOLS 1 Wireless communication system 3 Wireless node 5 Backbone network 7 Terminal device 9 Backhaul (BH) network 31 Processor 32 Memory 33 Storage 34 Input / output (I / O) device 35, 36 Wireless interface (IF)
37,39 Wired interface (IF)
38 Bus 301, 302 Wireless communication unit 303 Wired communication unit 304 Control unit 305 Storage unit 341 Scan processing unit 342 Node management unit 343 Tree path control unit 344 IPT control unit 350, 360 Antenna 3431 Route control packet generation unit 3432 Path metric calculation unit 3433 Tree path update unit 3411 Beacon transmission unit 3412 Request reception unit 3413 Response transmission unit 3414 Beacon reception unit 3415 Request transmission unit 3416 Response reception unit

Claims (4)

1. One wireless node of a plurality of wireless nodes,
   A transmission unit that transmits a first response signal to a transmission source of the first association request signal when receiving a first association request signal for the first beacon signal after transmitting the first beacon signal;
   A receiving unit for receiving a second response signal for the second association request after transmitting a second association request to a transmission source of the second beacon signal in response to reception of the second beacon signal;
   In response to the transmission of the first response signal, the wireless link information between the transmission source of the first beacon signal and the transmission source of the first association request signal is managed, and the reception of the second response signal And a management unit that manages information on a radio link between the transmission source of the second association request and the transmission source of the second beacon signal,
   A wireless node comprising:
2. The transmitter is
   According to the access point mode, transmitting the first beacon signal and transmitting the first response signal,
   The receiver is
   According to the station mode, the second beacon signal is received and the second response signal is received.
   The wireless node according to claim 1.
3. When the first association request signal for the first beacon signal is received after transmitting the first beacon signal, the first response signal is transmitted to the transmission source of the first association request signal,
   In response to receiving the second beacon signal, after transmitting the second association request to the transmission source of the second beacon signal, receiving a second response signal for the second association request,
   In response to the transmission of the first response signal, information on a radio link between the transmission source of the first beacon signal and the transmission source of the first association request signal is managed,
   In response to reception of the second response signal, information on a radio link between the transmission source of the second association request and the transmission source of the second beacon signal is managed.
   Wireless link establishment method.
4. To the processor,
   When the first association request signal for the first beacon signal is received after transmitting the first beacon signal, the first response signal is transmitted to the transmission source of the first association request signal,
   In response to receiving the second beacon signal, after transmitting the second association request to the transmission source of the second beacon signal, receiving a second response signal for the second association request,
   In response to the transmission of the first response signal, information on a radio link between the transmission source of the first beacon signal and the transmission source of the first association request signal is managed,
   In response to reception of the second response signal, information on a radio link between the transmission source of the second association request and the transmission source of the second beacon signal is managed.
   A wireless link establishment program that executes processing.

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