JP2003110478A - Radio relay system, radio apparatus, and node selection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radio relay system for selecting a radio relay apparatus for relaying the communication among pieces of radio apparatus from a plurality of pieces of radio apparatus, to provide a radio apparatus and a node selection method. SOLUTION: In the radio relay system where a plurality of radio systems comprising a plurality of pieces of radio apparatus that function as a relay node that performs relaying or a terminal node that does not perform relaying, each radio apparatus solves the problem by carrying a function for judging whether the radio apparatus functions as the relay node at predetermined time or as the terminal node.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wireless relay system, a wireless device and a node selection method for selecting a wireless relay device that relays communication between wireless devices from a plurality of wireless devices.

[0002]

2. Description of the Related Art In recent years, an ad hoc multi-hop network is one form of wireless communication network. An ad hoc multi-hop network is a wireless communication device (hereinafter referred to as a node) having a wireless relay function.
Is a communication network configured by (1), and a node on the way relays communication between nodes to which radio waves do not directly reach, thereby realizing communication between all nodes.

In an ad hoc multi-hop network, if all the signals received by all nodes are retransmitted,
Excessive relaying will occur, resulting in poor radio wave utilization efficiency, resulting in interference and excessive delay. Therefore, by using a large number of nodes having a relay function (hereinafter referred to as candidate nodes), a relay node that is actually in charge of relaying and a terminal node that is not actively involved in relaying are used, and useless radio waves are used. It is necessary to improve the use efficiency of radio waves by not performing.

Further, in selecting a relay node from the candidate nodes, it is necessary to find a combination of relay nodes that can communicate with each other and have as wide an interval as possible.

Here, one of the conventional relay node selecting methods is described.
The procedure for the lowest-id method is shown below.

First, all candidate nodes are initialized to a state of "node type undecided".

Among all the nodes, the node having the smallest node identification value for identifying each node is selected as a "relay node", and all the nodes within a certain distance from the relay node are "end nodes". ".

In the above, a node having the smallest node identification value is newly selected as a "relay node" from among the nodes in the "node type undecided" state that have not yet been selected, and a certain number of nodes are selected from the relay nodes. Candidate nodes in the “node type undecided” state within the distance are selected as “end nodes”.

The processing is repeated until there is no node in the "node type undecided" state.

According to the above procedure, all nodes can be classified into relay nodes and end nodes.

[0011]

However, in order to use the above-described selection method, the position information and node identifications of all candidate nodes are acquired, and the acquired information is collected by a computer that performs node selection. A mechanism for performing the relay node selection process and delivering the result of the selection process to each node is required.

Further, when the arrangement state of the nodes is fixed, the selection process may be performed in advance, and the result may be stored in advance in each node. However, when the node moves, etc. In this case, processing such as measurement of location information, aggregation of location information, and delivery of selection results is required each time.

Further, the above-mentioned relay node selection method (Lowe
In the st-id method), the procedure for selecting a relay node includes an iterative process, and the distance between nodes is included in the iterative process. Therefore, when the number of nodes increases, both the amount of calculation and the selection processing time increase, and enormous calculation is required just by checking the communication availability and communication distance in each combination.

In actual wireless communication, due to the propagation characteristics, the directivity of the antenna, and the asymmetry of the communication capability between the terminals, communication may not be possible even if the distance between the nodes is small, or vice versa. It may be possible to communicate. In the selection method described above, whether or not wireless communication is possible is determined based on whether or not the distance between the nodes is within a certain distance.
There is a high possibility that radio waves will not reach the end node and the relay node, or interference may occur between the relay nodes. In wireless communication, even if the position information of the transmitting node and the receiving node that perform communication is known, it is difficult to determine from the calculation whether or not communication is actually possible due to the radio wave propagation state and the antenna.

Further, the relay nodes selected by the above-mentioned method cannot communicate directly because of the distance. Therefore, after selecting a relay node by the method described above, a process of newly re-selecting a new relay node that is in charge of communication between the first selected relay nodes from the nodes once determined to be terminal nodes is separately performed. Will be needed.

The present invention has been made in view of the above problems, and a wireless relay system, a wireless device, and a node selection method capable of selecting a wireless device that can actually communicate with each other by reducing the amount of calculation for system construction. The purpose is to provide.

[0017]

In order to solve the above problems, the present invention employs means for solving the problems having the following features.

According to the invention described in claim 1, in a wireless relay system provided with a plurality of wireless systems configured by a plurality of wireless devices functioning as a relay node for relaying or a terminal node for not relaying, each wireless device is provided. Is characterized in that it is determined whether to function as the relay node or the terminal node at every predetermined time or at a predetermined time.

According to the first aspect of the invention, it is not necessary to collect the position information of each node, and the time required for the communication, calculation, and selection work performed by each node to be completed is determined by the relay node. It can be fixed regardless of the number of nodes that are selected.

According to a second aspect of the present invention, in the wireless device that constitutes the wireless relay system, the wireless device is made to function as the relay node or at the end node at predetermined time intervals or at predetermined times. It is characterized by making a determination.

According to the second aspect of the present invention, it is not necessary to collect the position information of each node, and the time required until the communication, calculation, and selection work performed by each node is completed is determined by the relay node. It can be fixed regardless of the number of nodes that are selected.

According to a third aspect of the present invention, a node determination signal capable of determining which one of the nodes is used is calculated for each radio device at predetermined time intervals or from a predetermined time. It is characterized in that it has a transmitting unit for transmitting at predetermined time intervals.

According to the third aspect of the present invention, the probability of occurrence of interference between wireless devices can be reduced and a relay route can be constructed efficiently.

The invention described in claim 4 is characterized in that, when the node determination signal is transmitted, the wireless device of its own becomes a relay node.

The invention described in claim 5 is characterized in that, when the node determination signal is received, the wireless device of its own becomes a terminal node without transmitting the node determination signal.

The invention described in claim 6 is characterized in that, when the wireless device receives a plurality of the node determination signals, it serves as a node that relays between the relay nodes that have transmitted the node determination signals. To do.

According to the invention described in claims 4 to 6, the transmission signal is selected, and the node which does not correspond to the relay node does not need to transmit the signal for selection in the selection process. Therefore, the power consumption of the node is reduced. The number can be reduced and the radio waves can be used efficiently.

According to a seventh aspect of the present invention, the node determination signal has identification information for identifying each wireless device.

According to the seventh aspect of the invention, it is possible to easily confirm from the identification information which wireless device is used to perform the relay.

The invention described in claim 8 is a node selecting method for selecting one of the nodes in a wireless device functioning as a relay node for relaying or an end node for not relaying, in the node selecting method. It has a transmission step of transmitting a node determination signal capable of determining which is at a predetermined time interval or from a predetermined time at a time interval calculated for each wireless device. And

According to the invention described in claim 8, it is possible to reduce the probability of occurrence of interference between wireless devices and to construct a relay route without the need to collect position information of individual nodes.

The invention described in claim 9 is characterized in that, when the node determination signal is transmitted, the wireless device of its own becomes a relay node.

The invention described in claim 10 is characterized in that, when the node determination signal is received, the wireless device of its own becomes a terminal node without transmitting the node determination signal.

According to the invention described in claims 9 to 10, the transmission signal is selected, and the node which does not correspond to the relay node does not need to transmit the signal for selection in the selection process. Therefore, the power consumption of the node is reduced. The number can be reduced and the radio waves can be used efficiently.

In the invention described in claim 11, when the radio device receives a plurality of the node determination signals,
The relay node is a node that relays between the relay nodes that have transmitted the node determination signal.

According to the twelfth aspect of the present invention, when a plurality of the node determination signals are received, the node relaying between the relay nodes confirms the communication connection via the node relaying between the relay nodes. It is characterized by performing.

According to the invention described in claims 11 to 12,
Even when constructing a large-scale wireless network having a large number of nodes to be accommodated, it is possible to easily cope with it.

The invention described in claim 13 is characterized in that the node determination signal has identification information for identifying each wireless device.

According to the thirteenth aspect of the present invention, it is possible to easily confirm from the identification information which wireless device is used to perform the relay.

[0040]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to the drawings.

In the present invention, the "wireless device" is a device having a function as a relay node, and is defined by the operation contents (node state) of the wireless device described below.
For ease of explanation, the names will be changed to relay devices (relay nodes), end nodes, and the like.

FIG. 1 is a diagram showing an example of the configuration of a wireless device according to the present invention.

The wireless device 10 shown in FIG.
And a storage unit 12 and a wireless communication unit 13. Further, the wireless communication unit 13 is configured to have a receiving unit 14 and a transmitting unit 15.

The time measuring unit 11 has a function of measuring time and instructing start of processing at a designated time or after a designated time has elapsed. The storage unit 12 also has a function of storing information such as the node identification of the self-node, the state of the self-node, the Y-node identification, the X-node identification, the operation history between the self-node and other nodes, the Y-node list, and the like. Wireless communication unit 13
Transmits and receives a signal from the antenna via the receiving unit 14 or the transmitting unit 15.

Here, the node identification is information assigned to each node for identifying each node, and is composed of, for example, numbers, numbers, characters, symbols and the like.

The node status includes the status of a Y node, an X node capable of relaying between Y nodes, or a terminal node. The Y node is a relay node that is selected with an interval such that it cannot directly communicate with each other. The X node is a relay node that can directly communicate with a plurality of Y nodes and mediates communication between the Y nodes. The terminal node is a node that can receive radio waves of one or more Y nodes.

Here, an example of the arrangement of the above-mentioned nodes is shown in the figure.

FIG. 2 is a diagram showing a communication range of each node and an arrangement example.

In FIG. 2, the Y1 node and the Y2 node cannot communicate with each other because they are located outside the communication range. The X1 node is the Y1 node within the communication range,
Since it includes the Y2 node, it can mediate communication between Y1 and Y2. The end nodes are scattered within the communication range from any one or more Y nodes. X1 in FIG.
The node, the Y1 node, the Y2 node, and the end node each have a device configuration such as the wireless device 10.

In the wireless device 10, a plurality of wireless devices 10 simultaneously execute the relay node selection procedure. Each wireless device 1
For 0, the respective node states are determined by executing the relay node selection procedure.

The Y node described above corresponds to a cluster header of a cluster type network generally used in an ad hoc multi-hop network, and the X node corresponds to a gateway connecting clusters.

In order for the wireless device 10 to actually relay the communication from each node as an ad hoc multi-hop network, a relay node connection process for connecting the Y node and the X node selected by the relay node selection procedure is performed. , Path setting processing for setting a path for relaying communication from each node is required.

However, by utilizing the present invention,
A relay network in which the Y nodes, the X nodes, and the end nodes are connected and the relay nodes are mutually connected can be constructed.

Further, according to the present invention, the communication between the relay nodes directly connected by the relay network is possible, but in the case of performing the communication via the plurality of relay nodes, the route of the communication is relayed. It is necessary to solve the problem.

This is a problem of route control, and as a route control method in an ad hoc multi-hop network,
For example, IETF (Internet Engineering Task Forc)
e) "Charles E. Perkins, Eli
zabeth M. Royer, Samir R. Das, Ad hoc On-Demand Di
stance Vector (AODV) Routing, draft-ietf-manet-aod
v-08.txt, 2001 ”etc. can be used to solve the problem.

Next, a method of synchronizing the time in each wireless device 10 will be described.

In the relay node selection process, each node that performs the relay node selection needs to perform the Y node selection process and the X node selection process at timings of approximate time. Therefore, each node has a function of executing a process by designating a time using the time measuring unit 12, a function of acquiring operating time information, and a function of correcting the time of the time measuring unit 12.

As a method of acquiring the operation time information, for example, the operation time may be acquired by broadcasting or communication, and the time when the past relay node selecting process is executed,
Alternatively, the next operation time may be calculated based on a certain rule based on the time when the signal used in the relay node selection process is received, or acquired by another method for the signal used in the relay node selection process. The node which has added the operation time information and sent the signal and which has received the signal may analyze the added operation time information and calculate subsequent operation time information.

As a method of correcting the time of the time measuring unit 12, for example, time information may be acquired and corrected by broadcasting or communication, or it may be corrected using a specific signal which is not limited to the time information. Alternatively, the user may directly correct the time. Further, time information may be added to the signal used in the relay node selection processing and transmitted, and the time may be corrected based on the relationship between the signal reception time and the time information.

Next, a procedure in which the wireless device 10 selects a relay node will be described.

The nodes that perform the relay node selection process perform the relay node selection process during the common operation time (T0, T2, T4). It is assumed that the time of each wireless device 10 that performs the selection process is synchronized by the method as described above.

First, the Y node is selected from the time T0 to T2, and then the X node is selected from the time T2 to T4.
Select a node. After the selection of the relay node is completed, the relay node connection processing for confirming the communication between the selected Y node and the X node is performed as necessary. By performing the connection process, a relay network confirmed to be mutually connectable is constructed.

If the selection of the X node that mediates the communication between the Y nodes is performed by using another method or the like, the relay selection process may be ended at the time of T2. At the time of T2, each node is classified into a Y node and an end node.

Next, the procedure in which the wireless device 10 selects a relay node and confirms the connection will be described in detail with reference to the drawings.

FIG. 3 is an example of a flowchart for selecting a relay node in the present invention up to confirmation of connection.

FIG. 4 is a diagram showing an example of a communication state at the time of relay node selection processing of the wireless relay device.

In FIG. 4, node 1, node 2, node 3, and node 4 exist as candidate nodes, and node 1 and node 2, node 2 and node 3, and node 3 and node 4 can communicate with each other. The timing when these nodes perform the relay node selection processing in a certain state is shown in the figure with the horizontal axis representing time.

Next, the procedure will be described with reference to FIG.

In FIG. 3, the Y node selection start time T0
Before this, a Y node selection preparation process (S31) is performed. Each node (hereinafter referred to as each node) that performs the relay node selection processing initializes the state of the node to the state of the terminal node, initializes the reception record of the Y node signal, and calculates the scheduled time T1 for transmitting the Y node signal. To do.

Here, the time T1 is calculated individually for each node. Because multiple nodes are Y
This is because interference may occur when a node signal is transmitted, and in the calculation of T1, processing for spreading the value of T1 is performed in order to reduce the probability of occurrence of interference. For example, by using a random number or a pseudo-random number sequence, from T0 to T
You may spread uniformly in the range of 2. Further, when it is desired to increase the probability that a specific node is selected as a relay node, calculation may be performed so as to take a range close to T0, and conversely, a node whose lower probability is selected as a relay node is T2.
You may calculate so that the range close to may be taken.

Next, when the Y-node selection preparation process (S31) is completed, each node operates from time T0 to T2.
A Y node selection process (S32) is performed. Table 1 shows an example of event processing in the Y node selection processing.

[0072]

[Table 1] When the receiving unit 14 receives a Y node signal from another node, the Y node selecting process (S32) stores the Y node identification of the signal. If the Y node that can communicate with the self node is not detected when the time becomes T1, the self node becomes the Y node, and the Y node signal is transmitted by the transmitter 15.
Send at.

Table 2 shows an example of the Y node signal.

[0074]

[Table 2] The Y node signal includes at least a Y node signal identification and a Y node identification. The Y node signal identification is a symbol for identifying the Y node signal from other signals, and the Y node identification is Y.
This is a symbol for identifying the transmission node that is the transmission source that has become a node and other nodes.

Here, it is sufficient if the self node can normally detect the Y node from time T0 to T1.
If the receiving unit 14 cannot receive the Y node signal normally, it is treated as undetected. Even if the Y node signal is successfully received, the received Y signal is received from the past operation history accumulated in the storage unit 12 in the received wireless device 10.
If it is found that bidirectional communication with the node signal transmission node has not been possible for some reason, it is possible to use a method such as undetecting.

In FIG. 4, respective times T1 calculated by the nodes 1, 2, 3, and 4 are calculated.
a, T1b, T1c, and T1d are T1a <T1c <T1b <T1d in the time amount from T0.

First, the node 1 becomes the Y node by transmitting the Y node signal in the transmitting section 15 at the timing of T1a. The node 2 receives this signal at the receiving unit 14,
The node 1 is stored as the Y node based on the Y node identification information of the node signal.

Next, the node 3 transmits the Y node signal at the transmission unit 15 at the timing of T1c to become the Y node. The node 2 and the node 4 receive this signal at the receiving unit 14, and each stores the node 3 as the Y node.

Since node 2 has received the Y node signals of node 1 and node 3 by T1b, it does not transmit the Y node signal. Since the node 4 has also received the Y node signal of the node 3 by T1d, it does not transmit the Y node signal.

At time T2, the selection of the Y node is completed.
When the relay node selection process is completed at this stage, in FIG. 4, the nodes 1 and 3 are selected as Y nodes, and the nodes 2 and 4 are the end nodes. Further, the node 2, which is the terminal node, stores in the storage unit 12 that the node 1 and the node 3 are Y nodes and the node 4 stores that the node 3 is a Y node.

Further, in S32, the end node which can normally detect the Y node signal transmitted from the plurality of Y nodes existing in close proximity at a close timing is under the condition close to the actual radio wave propagation state such as radio wave interference. Since the signal from the Y node can be received below, there is a high possibility that data can be received normally in the network configuration after the present invention is implemented.

Next, as the X node selection preparation process before the X node selection process, initialization of the reception record of the X node signal and calculation of the X node signal transmission scheduled time T3 are performed (S3).
3).

The calculation of the time T3 is made individually for each node. If a plurality of nodes transmit X node signals at the same time by the transmitting unit 15, interference may occur. Therefore, in the calculation of T3, in order to reduce the probability of occurrence of interference, processing for spreading the value of T3 should be performed. To do.

For example, using a random number or a pseudorandom number sequence, T
It may be spread uniformly in the range of 2 to T4, and in a node that wants to increase the probability of being selected as an X node, it may be calculated so as to take a range close to T2. A node for which the probability of being elected may be reduced may be calculated so as to have a range close to T4.

A Y node or an end node that has not received a plurality of Y node signals between T0 and T2 does not transmit an X node signal, and therefore does not need to calculate T3.

Each node has X for the time from T2 to T4.
Node selection processing is performed (S34).

Table 3 shows an example of event processing in the X node selection processing.

[0088]

[Table 3] In the X node selection processing (S34), when the receiving unit 14 receives an X node signal from another node, the X node identification of the signal is stored in the storage unit 12. At time T3, the self node is not the Y node and a plurality of Y nodes
If it is not the end node receiving the node signal and the signal of the X node from another node is not detected,
It becomes the X node and the X node signal is transmitted by the transmission unit 15.

Table 4 shows an example of the X node signal.

[0090]

[Table 4] The X node signal includes at least an X node signal identification, an X node identification, and a Y node list. The X node signal identification is a symbol that identifies an X node signal from another signal, the X node identification is a symbol that identifies a transmission node that has become an X node from another node, and the Y node list is , A list including the Y node identification of the Y node received by the X node at the receiving unit 14.

Here, as a method of detecting duplication with another X node signal, for example, a method of considering the reception of another X node signal as duplication, or a Y node list of the received other X node signal, A method is considered in which the case where all the Y nodes received by the self node are included is regarded as duplication.

At time T4, the X node and the Y node are selected as relay nodes. At this point, each node has its own node classified as either an X node, a Y node, or an end node. Each node can know the relay node that the self node can receive from the received X node signal and Y node signal.

The node selected as the Y node can confirm that it can communicate with the X node that has transmitted the X node signal, if its Y node identification is included in the Y node list of the received X node signal. Further, it is possible to confirm which Y node can be communicated with via the X node from the information of other Y node identification in the X node signal.

Here, the Y node that has not received the X node signal by the time of T4 is an isolated node that cannot communicate with other relay nodes.

Since the X node receives signals from two or more Y nodes, it may communicate with the Y node, but at this point, the signal transmitted by the X node is transmitted to the Y node. Can not be confirmed whether it can be received correctly. Also, the end node receives one or more Y node signals from the Y node selected as the relay node. At this point, it is not possible to confirm whether the Y node can receive the signal transmitted by the end node. Not not.

In the example of FIG. 4, only the node 2 receives a plurality of Y node signals at the time T2. The node 2 transmits the X node signal including the node 1 and the node 3 as the Y node identification at the time of T3 by the transmitting unit 15.

When the receiving unit 14 receives the X node signal, the node 1 and the node 3 perform bidirectional communication with the node 2 because their own node identification is included as the Y node identification. I have obtained information that I can do.

The nodes 1 and 3 are the nodes 1
And that the node 3 may be able to communicate via the node 2 as information.

The node 4 has obtained that the node 3 is the Y node as information.

As described above, the relay node selection processing (S34)
Is complete.

However, in the above-described processing of S31 to S34, the Y node has the information of the X node confirmed to be communicable, but the X node confirms only the reception with the communication with the Y node. Not not. That is, the connection between the relay nodes has not yet been confirmed at this point.

Therefore, in order to actually construct the relay network, the relay node connection processing (S35) is required after the relay node selection processing. Relay node connection processing (S
In 35), it is sufficient that the confirmation information of the communication is transmitted from the Y node to the X node and the Y node and the X node can recognize the adjacent node. The adjacent node is a node with which a specific relay node can directly communicate.

However, the connection processing of the relay node may change depending on the topology of the network to be constructed. Therefore, as an example of the relay node connection processing (S35), the following two examples will be described.

In the radio device 10 which performs the relay node connection processing (S35), the storage unit 12 has a function of holding the adjacent node as information. The adjacent node information is the node identification of another node with which the relay node can directly communicate.

First, an example of relay node connection processing (example 1) capable of constructing a network topology for connecting all relay nodes which have confirmed communication will be described.

Table 5 shows an example of event processing at the time of relay node connection processing in this example.

[0107]

[Table 5] From time T4 to T6, the Y node sends out an X node confirmation signal, and the X node receives this signal, so that communication confirmation to the X node and connection processing can be realized at the same time. Time T6
May be specified by, for example, broadcasting or communication,
Alternatively, the time may be a time that has elapsed by a preset time from the relay node selection start time T0, T2, or T4.

If there is an X node that has transmitted the X node signal including its own Y node in the Y node list, the Y node records the X node as an adjacent node and connects the node identifications of all the adjacent nodes. The X node confirmation signal included in the node list is transmitted.

Table 6 shows an example of the X node confirmation signal.

[0110]

[Table 6] The X node confirmation signal includes at least an X node confirmation signal identification, a Y node identification, and a connection node list. The X node confirmation identification is a symbol that identifies the X node confirmation signal from other signals, and the Y node identification is a symbol that identifies the transmission node that has become the Y node from other nodes. Is a list containing the X node identifications of the X nodes that the Y node has confirmed connectivity to.

The X node confirmation signal may be transmitted at time T5 before reaching T6. For example, the time when each Y node transmits the Y node signal during the Y node selection processing (S32). By transmitting the X node confirmation signal by using T1, it is possible to reduce the probability that the X node that receives the X node confirmation signals from a plurality of Y nodes will interfere.

For example, if the time interval between T0 and the transmission time T1 of the Y node signal transmitted from each node is ΔT, then ΔT
Only the time elapsed from T4 may be set as time T5, and Δ
The time when T is multiplied by a constant value and the constant value is added may be time T5.

In the example of FIG. 4, the times T1 to T0 + T4 are used as the calculation method of the time T5 in the nodes 1 and 3. The node 1 records the node 2 as the adjacent node and then adds the node 2 to the connected node list at the time T5a.
The transmitting unit 15 transmits the X node confirmation signal including the.
The node 2 receives the signal at the receiving unit 14 and the node 1
Is added to the adjacent node. The node 3 records the node 2 as the adjacent node, and then, at time T5b, the transmitter 15 transmits the X node confirmation signal including the node 2 in the connection node list. The node 2 receives the signal at the receiving unit 14 and adds the node 3 to the adjacent node. As a result, the node 2 confirms the connection between the node 1 and the node 3.

The X node receives the X received by the time T6.
The Y node including its own X node identification is recorded as the adjacent node in the node confirmation signal. By this relay node connection processing (S35), all the X nodes and the Y nodes can record the information of the adjacent nodes whose mutual communication is confirmed in the recording unit 12 by the time T6, and the wireless relay is performed. A network is built.

Next, an example (example 2) of the relay node connection processing (S35) for forming the topology for connecting the X node and the Y node so as to form a tree structure having a special node as a root will be described.

In this case, each node needs to have a function of storing the node identification of the upper node. At time T4, the special node to be the root transmits the tree structure creation signal to the X node or the Y node that has been received by the receiving unit 14 by the transmitting unit 15, and the tree is generated. Start creating a network of structures. Other nodes are time T
By the time of 4, the node identification of the upper node is initialized.

The tree structure creation signal includes at least the sending node identification and the child node list. Here, the transmission node identification is the node identification of the node that has transmitted the tree structure creation signal.

When the Y node whose stored node identification of the upper node remains in the initialized state receives the tree structure creation signal at the receiving unit 14, the node identification of its own node becomes
When it is included in the child node list of the received tree structure creation signal, the self node sets the node described in the sending node identification as a child node having the upper node.

Next, the sending node is stored as an upper node, and an X node list created from the X node signals received by the receiving unit 14 so far from which the node identification of the upper node is removed is a child node list. Then, a new tree structure creation signal including the child node list is transmitted from the transmission unit 15 with the self node as the transmission node identification.

The node identification in the X node list is
When it is described in the child node list of the received tree structure creation signal, the node identification may be excluded from the child node list of the self node or the child node list of the tree structure creation signal transmitted by the self node.

Next, the X node whose node identification of the upper node stored in the storage unit 12 remains in the initialized state is
When the tree structure creating signal is received by the receiving unit 14, when the node identification of the self node is included in the child node list of the received tree structure creating signal, the self node is the node described in the sending node identification. Is set as a child node whose upper node is. Next, the sending node is stored as the node identification of the upper node, and the node identification of the upper node is removed from the Y node list created from the Y node signals received so far to obtain the child node list,
A new tree structure creation signal including the child node list is transmitted from the transmission unit 15 using the self node as the transmission node identification.

If the above X node holds the X node signal transmitted from another X node,
In the child node list, in addition to the nodes in the Y node list,
The transmission node identification of the received X node signal may be added, and further, the transmission node identification of the held X node signal is described in the child node list of the received tree structure creation signal. In addition, the node identification may be excluded from the child node list of the self node or the child node list of the tree structure creation signal transmitted by the self node.

By alternately propagating the tree structure creating signal between the Y node and the X node, the X node and the Y node are connected. If the X node holds an X node signal transmitted by another X node, the tree structure creation signal may be propagated from the X node to another X node.

Relay node selection processing in example 2 (S3
In 5), when the selection of the X node and the Y node is completed, the communication from the X node to the Y node and the communication from the terminal node to the relay node are not confirmed. Therefore, even if the relay node connection process is performed, there may occur a Y node that cannot be connected to another node or an end node that cannot be connected to the relay node. A node not connected to such a relay node needs to request a terminal node in the vicinity where it can communicate from the self node to become a relay node when communication becomes necessary. By introducing the relay request processing to such a neighboring node, the reliability of the connection can be improved.

In the ad hoc network, since the relay node used for communication is likely to move or disappear, the relay request process is not peculiar to the relay node selection process and is essential. It is provided as a function.

Also in the above-mentioned example 2, the connection of the relay node can be confirmed as in the case of example 1.

By utilizing the present invention, it is possible to easily construct a wireless relay network by transmitting and receiving signals corresponding to various network forms (topologies).

[0128]

As described above, according to the present invention, it is not necessary to collect position information of individual nodes in the process of selecting relay nodes in a wireless relay system such as an ad hoc multi-hop network, and A wireless relay device selecting method, a wireless device, and a network using the same which can make the time required for the communication, calculation, and selection work performed by a node to be constant irrespective of the number of nodes performing relay node selection A system can be provided.

Even if the number of nodes that select relay nodes becomes very large, the selection of relay nodes is always completed within a fixed time. Therefore, when constructing a large-scale wireless system with a large number of nodes to accommodate. Since the time until construction can be easily grasped, it becomes possible to perform efficient work in system development or system operation.

Further, when the relay node selection method of the present invention is used, nodes that do not correspond to relay nodes do not need to transmit a signal for selection in the selection process, so that the power consumption of the node can be reduced. .

Moreover, at the time of completion of the selection, each node holds the information indicating which node is selected as the relay node within the range that it can receive.
After the selection process is completed, it is possible to omit communication to notify each node of the relay node again, so that radio waves can be efficiently used.

[Brief description of drawings]

FIG. 1 is a diagram of a configuration example of a wireless device according to the present invention.

FIG. 2 is a diagram of a communication range of each node and an arrangement example.

FIG. 3 is an example of a flowchart for selecting a relay node in the present invention up to confirmation of connection.

FIG. 4 is a diagram showing an example of a communication state during a relay node selection process of a wireless device.

[Explanation of symbols]

10 wireless devices 11 Time measurement section 12 Memory 13 Wireless communication section 14 Receiver 15 Transmitter

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yoshinori Izumi             1-10-11 Kinuta, Setagaya-ku, Tokyo, Japan             Broadcasting Association Broadcast Technology Institute (72) Inventor Makoto Yamamoto             1-10-11 Kinuta, Setagaya-ku, Tokyo, Japan             Broadcasting Association Broadcast Technology Institute (72) Inventor Toshiyuki Fujisawa             2-2-1 Jinnan 2-chome, Shibuya-ku, Tokyo             Sending Association Broadcast Center F term (reference) 5K033 AA01 AA04 CB06 DA02 DA17                       DB18                 5K072 AA11 BB27 CC04 DD16 DD17                       EE31 FF11 GG12 GG13 GG14                       GG26

Claims (13)

[Claims] 1. A wireless relay system comprising a plurality of wireless systems configured by a plurality of wireless devices functioning as a relay node for relaying or a terminal node for not relaying, wherein each wireless device is provided at predetermined time intervals or in advance A wireless relay system, which determines whether to function as the relay node or the terminal node at a predetermined time. 2. In a wireless device that constitutes the wireless relay system, every predetermined time or at a predetermined time,
A radio apparatus for determining whether to function as the relay node or the terminal node. 3. A node determination signal capable of determining which one of the nodes is transmitted is transmitted at a predetermined time interval or from a predetermined time with a time interval calculated for each wireless device. The wireless device according to claim 2, further comprising: 4. When the node determination signal is transmitted,
4. The wireless device according to claim 2, wherein the wireless device of its own serves as a relay node. 5. When the node determination signal is received,
5. The wireless device according to claim 2, wherein the wireless device of its own becomes a terminal node without transmitting the node determination signal. 6. The wireless device, when receiving a plurality of the node determination signals, becomes a node that relays between the relay nodes that have transmitted the node determination signals. The wireless device according to claim 1. 7. The wireless device according to claim 2, wherein the node determination signal has identification information for identifying each wireless device. 8. A node selection method for selecting one of the nodes in a wireless device that functions as a relay node that performs relay or a terminal node that does not perform relay, and determines whether the node is one of the nodes. A node selection method, comprising: a transmission step of transmitting a node determination signal capable of performing the transmission, at predetermined time intervals or from a predetermined time at a time interval calculated for each wireless device. 9. When the node determination signal is transmitted,
9. The node selection method according to claim 8, wherein its own wireless device serves as a relay node. 10. The node selection method according to claim 8, wherein when the node determination signal is received, the wireless device of its own becomes a terminal node without transmitting the node determination signal. 11. The wireless device, when receiving a plurality of the node determination signals, becomes a node that relays between the relay nodes that have transmitted the node determination signals. The method for selecting a node according to one item. 12. When a plurality of the node determination signals are received, the node relaying between the relay nodes confirms the communication connection via the node relaying between the relay nodes. 12. The node selection method according to any one of 8 to 11. 13. The node selection method according to claim 8, wherein the node determination signal has identification information for identifying each wireless device.