JP6599044B2 - Wireless communication device - Google Patents

Description

  The present invention relates to a technique for performing wireless communication between wireless stations.

The wireless mesh network includes a plurality of wireless devices for the purpose of collecting various types of automation information or various types of sensor information wirelessly.
In a wireless mesh network, RPL (Routing Protocol for Low Power and Lossy Networks), which is one of routing protocols, is used.
RPL is a routing protocol for the purpose of using a low power consumption or low resource terminal (for example, a wireless sensor) in an unstable communication environment, and is standardized by RFC 6550 of IETF (Non-Patent Document). 1).

RPL is DODAG (Destination Oriented Directed
It is formed by a tree structure called “Acrylic Graph”.
In RPL, a path control message called DIO (DODAG Information Object) is used to construct an upstream path.
Also, in RPL, DAO (Destination is used to construct a downstream route.
A route control message called Advertisement Object) is used.
In addition, in RPL, a route control message called DIS (DODAG Information Solition) is used to search for an upstream route.

A radio station that constructs a route using the RPL protocol performs transmission and reception of DIO and DAO to construct a route. Specifically, the wireless station transmits / receives a route control message to / from neighboring wireless stations, and selects a connection destination in the route so as to be as close as possible to the parent station in the route, thereby constructing a route.
The DIO is a message for a wireless station whose path has been established to inform its existence, and is transmitted by broadcast.
The DIO is transmitted from each radio station including the master station, and each radio station excluding the master station selects an uplink path from the DIOs received from other radio stations.
DAO is a message for requesting connection of a downlink path, and is transmitted by unicast to a radio station selected by a downlink radio station as an uplink radio station. The upstream radio station receives the DAO and sets the DAO transmission source as the downstream radio station.

For example, the master station # 0 transmits DIO by broadcasting. Then, the DIO of the master station # 0 reaches each of the slave stations # 1 and # 2 within the coverage of the master station # 0. The slave station # 1 and the slave station # 2 select the master station # 0 as the upstream radio station, and transmit DAO to the master station # 0 by unicast. Thereby, the slave station # 1 and the slave station # 2 complete the path construction.
The slave station # 1 and the slave station # 2 that have completed the path construction transmit DIO by broadcast. The DIO of the slave station # 2 reaches the master station # 0, the slave station # 1, and the slave station # 3 within the coverage of the slave station # 2. Only the DIO of the slave station # 2 reaches the coverage of the slave station # 3. Therefore, the slave station # 3 transmits DAO to the slave station # 2 by unicast, and completes the path construction. The slave station # 2 transmits the DAO of the slave station # 3 to the master station # 0, which is an upstream radio station.

The upstream radio station and the downstream radio station are located within the communication range of each other. The communication range is called coverage.
The coverage of the master station # 0 and the coverage of the slave station # 3 do not overlap each other. Therefore, the master station # 0 and the slave station # 3 cannot be directly connected to each other, and the slave station # 2 whose coverage overlaps with both stations is responsible for relaying.

  In order to avoid message collision as much as possible between the wireless stations with overlapping coverage, carrier sense is always performed before transmission. Each wireless station confirms that no other wireless station is transmitting a message, and then starts transmitting a message.

Transmission of DIO and DAO by each wireless station is performed not only at the time of path construction after startup but also periodically so that path abnormality can be detected. As a result, the route continues to be maintained.
When the DIO is not received from the uplink radio station for a certain period, the downlink radio station determines that communication with the uplink radio station is not possible. Then, the downlink radio station changes the route by selecting a new uplink radio station.
When the DAO from the station on the downstream path is not received for a certain period, the local station determines that communication with the station on the downstream path is impossible, and deletes the downstream path to the station.

JP 2014-216726 A

“RPL: IPv6 Routing Protocol for Low-Power and Lossy Networks”, IETF, RFC 6550, March, 2012.

Patent Document 1 indicates that an instruction to change the transmission interval is given in accordance with the number of radio stations in the coverage. By changing the transmission interval at each wireless station, message collision is reduced.
However, the technique disclosed in Patent Document 1 is a technique for avoiding a collision with a message transmitted from a radio station in the same coverage.

The wireless mesh network using RPL has the following problems.
Each wireless station cannot detect that a wireless station that is not in coverage is transmitting a message. Therefore, when the first radio station in the first coverage and the second radio station in the second coverage transmit a message at the same time, the first radio in the third radio station included in both the first coverage and the second coverage. The message of the station and the message of the second wireless station collide.

Each wireless station performs DIO transmission when the period timer for DIO transmission expires, and the downstream wireless station that receives DIO from the upstream wireless station performs DAO transmission when the period timer for DAO transmission expires. Such an operation is periodically repeated. Thereby, each wireless station maintains a route.
However, if a DIO or DAO collision occurs, the path maintenance is suspended until the next opportunity.

In preparation for failure in message transmission / reception including such a collision, it is possible to maintain the route by increasing the period of detecting the route abnormality.
However, if the detection period of the path abnormality is extended, the time required for detecting the path abnormality also becomes longer. If detection of a path abnormality is delayed, it will take time until the system is restored by changing the path, and data communication cannot be normally performed until the system is restored.
Specifically, when a plurality of radio stations use the same radio station as an upstream radio station, the plurality of radio stations perform DAO transmission in response to DIO reception from the same radio station. Since a plurality of radio stations have different coverages, a plurality of DAOs transmitted from different coverages may collide with each other on the upstream radio station. The more downstream radio stations, the higher the probability that DAOs transmitted from different coverages will collide with upstream radio stations.

If random numbers are applied within a large range in the DAO transmission cycle, the probability of collision can be reduced. The RPL does not specifically define the DAO transmission period.
However, there is no clear means for applying random numbers within a large range in the DAO transmission cycle.
Therefore, it is necessary to set a range of random numbers to be applied to the DAO transmission cycle, assuming the maximum number of wireless stations terminated in the network.
As a result, the greater the number of radio stations that serve as relay stations, the longer it takes to reach DAO from each slave station to the master station.
For example, when the DAO of the slave station # 3 reaches the master station # 0 via the slave station # 2, the period required for transmission of DAO from the slave station # 3 to the slave station # 2, and the slave station # 2 The sum of the period required for transmitting DAO to the master station # 0 is the time required for the master station # 0 to detect that the slave station # 3 has completed the network connection.

The maximum required time required for DAO to reach the master station from the slave station is obtained by the following equation.
Maximum required time = Maximum time of DAO transmission cycle × (Number of relay stations + 1)
The DAO transmission cycle is determined by a random number. “+1” means DAO transmission from the slave station to the first relay station.

  In other words, if the range of random numbers applied to the DAO transmission cycle is greatly extended, the time required for route construction at startup and the time required for route change during operation will increase for the entire network.

  An object of the present invention is to enable a message to be transmitted at an appropriate transmission period.

The wireless communication apparatus of the present invention operates as a local station that is one of wireless stations.
The wireless communication device
Self-coverage information that is information on radio stations that exist within the coverage of the local station, and information on radio stations that exist within the coverage of a downlink station that is one of the radio stations that exist within the coverage of the local station. A storage unit for storing downlink coverage information;
A receiving unit for receiving a downlink message;
When the downlink message is received, a timer unit that starts a downlink timer in which a downlink transmission period determined based on the own coverage information and downlink coverage information stored in the storage unit is set;
A transmission unit that transmits a message including self-coverage information stored in the storage unit when the downlink timer expires.

  ADVANTAGE OF THE INVENTION According to this invention, a message can be transmitted with the suitable transmission period determined based on own coverage information and downlink coverage information.

1 is a configuration diagram of a wireless communication device 100 according to Embodiment 1. FIG. 1 is a configuration diagram of a wireless communication system 200 according to Embodiment 1. FIG. FIG. 3 shows a format of DIO in the first embodiment. FIG. 3 shows a format of a DODAG configuration in the first embodiment. FIG. 3 is a configuration diagram of a coverage management table 210 in the first embodiment. 4 is a flowchart of the operation of the master station in the first embodiment. 4 is a flowchart of operations of a slave station in the first embodiment. 4 is a flowchart of operations of a slave station in the first embodiment. 4 is a flowchart of operations of a slave station in the first embodiment. The flowchart of the random number range update (S300) in Embodiment 1. FIG. The flowchart of the random number range update (S300) in Embodiment 1. FIG. 5 is a flowchart of timer activation processing in the first embodiment. 5 is a flowchart of message generation processing in the first embodiment. 5 is a flowchart of reception processing in the first embodiment. 6 is a flowchart of transmission processing in the first embodiment. 6 is a flowchart of uplink station registration according to the first embodiment. 6 is a flowchart of registration of a downlink station in the first embodiment. 5 is a flowchart of updating own coverage information in the first embodiment. FIG. 9 is a diagram showing a format of transit information in the second embodiment. 9 is a flowchart of reception processing in the second embodiment. 10 is a flowchart of message generation processing according to the second embodiment. FIG. 6 is a configuration diagram of a wireless communication apparatus 100 in a third embodiment. FIG. 6 is a configuration diagram of a wireless communication apparatus 100 according to a fifth embodiment. 10 is a flowchart of reception processing in the fifth embodiment. The hardware block diagram of the radio | wireless communication apparatus 100 in embodiment.

  In the embodiments and the drawings, the same reference numerals are assigned to the same elements and corresponding elements. Description of elements having the same reference numerals will be omitted or simplified as appropriate. The arrows in the figure mainly indicate the flow of data or the flow of processing.

Embodiment 1 FIG.
A mode for determining an appropriate transmission period of DIO and DAO will be described with reference to FIGS.

*** Explanation of configuration ***
Based on FIG. 1, the structure of the radio | wireless communication apparatus 100 is demonstrated.
The wireless communication device 100 is a computer including hardware such as a processor 901, a memory 902, an auxiliary storage device 903, an RF circuit 904, a PHY control circuit 905, an antenna 906, and an oscillator 907. These hardwares are connected to each other via signal lines.

The processor 901 is an IC (Integrated Circuit) that performs arithmetic processing, and controls other hardware. For example, the processor 901 is a CPU (Central Processing Unit), a DSP (Digital Signal Processor), or a GPU (Graphics Processing Unit).
The memory 902 is a volatile storage device. The memory 902 is also called main memory or main memory. For example, the memory 902 is a RAM (Random Access Memory). Data stored in the memory 902 is stored in the auxiliary storage device 903 as necessary.
The auxiliary storage device 903 is a nonvolatile storage device. For example, the auxiliary storage device 903 is a ROM (Read Only Memory), a HDD (Hard Disk Drive), or a flash memory. Data stored in the auxiliary storage device 903 is loaded into the memory 902 as necessary.

The RF circuit 904 is a circuit that performs wireless communication. RF is an abbreviation for Radio Frequency.
The PHY control circuit 905 is a circuit that controls the physical layer. PHY is Physical
Abbreviation for Layer.
The antenna 906 is an antenna for realizing wireless communication.
The oscillator 907 is a circuit that generates clock pulses.

  The wireless communication apparatus 100 includes software elements such as a coverage management unit 110, a timer unit 120, a message generation unit 130, and a route management unit 140. A software element is an element realized by software.

The auxiliary storage device 903, a wireless communication Simple program for causing a computer to function as the coverage manager 110 and the timer unit 120 and the message generator 130 and the path management unit 140 is stored. The wireless communication program is loaded into the memory 902 and executed by the processor 901.
Further, the auxiliary storage device 903 stores an OS (Operating System). At least a part of the OS is loaded into the memory 902 and executed by the processor 901.
That is, the processor 901 executes the wireless communication program while executing the OS.
Data obtained by executing the wireless communication program is stored in a storage device such as the memory 902, the auxiliary storage device 903, a register in the processor 901, or a cache memory in the processor 901.

The memory 902 functions as a storage unit 191 that stores data. However, another storage device may function as the storage unit 191 instead of the memory 902 or together with the memory 902.
The RF circuit 904 functions as a receiving unit 192 that receives data. Further, the RF circuit 904 functions as a transmission unit 193 that transmits data.

  The wireless communication device 100 may include a plurality of processors that replace the processor 901. The plurality of processors share the role of the processor 901.

  The wireless communication program can be stored in a computer-readable manner in a nonvolatile storage medium such as a magnetic disk, an optical disk, or a flash memory. A non-volatile storage medium is a tangible medium that is not temporary.

Based on FIG. 2, the structure of the radio | wireless communications system 200 is demonstrated.
The wireless communication system 200 is a system including a plurality of wireless stations.
A solid line circle indicates a wireless station. A symbol in a solid circle is a station number for identifying a radio station.
The wireless communication device 100 operates as a wireless station.

Radio station # 0 is a master station in the radio communication system 200.
Radio stations # 1 to # 9 are slave stations in the radio communication system 200.

The range over which radio waves from the radio station reach, that is, the communication range of the radio station is called coverage.
Dashed ellipses indicate the respective coverages of the radio station # 0, the radio station # 1, the radio station # 5, and the radio station # 6.

A radio station existing in the coverage is called a coverage inner station.
The number of stations in the coverage is called the number of stations in the coverage.
A list of radio stations existing in the coverage is referred to as a coverage internal station list.
The number of stations in coverage and the list of stations in coverage are called coverage information.
For example, the in-coverage stations of the wireless station # 6 are the wireless station # 1, the wireless station # 6, the wireless station # 7, and the wireless station # 9. That is, the number of in-coverage stations of wireless station # 6 is four.

An in-coverage station that overlaps between coverages is called an overlapping station.
The number of in-coverage stations that overlap between coverages is referred to as the number of overlapping stations.
For example, the overlapping stations in the coverage of the wireless station # 6 and the coverage of the wireless station # 1 are the wireless station 1, the wireless station # 6, and the wireless station # 7. That is, the number of overlapping stations in the coverage of the wireless station # 6 and the coverage of the wireless station # 1 is three.

Each wireless station operates as its own station.
The own station directly communicates with the in-coverage station of the own station.
The own station communicates with a radio station that is out of the coverage of the own station via the in-coverage station of the own station.
For example, the wireless station # 6 directly communicates with each of the wireless station # 1, the wireless station # 7, and the wireless station # 9. Radio station # 6 communicates with radio station # 0 via radio station # 1.

A thick dotted line indicates a communication path.
In the communication path, the direction approaching the radio station # 0 is referred to as “up”, and the direction away from the radio station # 0 is referred to as “down”. The upstream communication path is referred to as an upstream path, and the downstream communication path is referred to as a downstream path.
A radio station located next to its own station in the uplink path is called an uplink station.
A radio station located next to its own station in the downlink path is called a downlink station.
For example, the upstream station of the wireless station # 6 is the wireless station # 1, and the downstream station of the wireless station # 6 is the wireless station # 9.

  The coverage information of the own station is called own coverage information, the coverage information of the uplink station is called uplink coverage information, and the coverage information of the downlink station is called downlink coverage information.

In the wireless communication system 200, a route control message for establishing a communication route is communicated.
A route control message transmitted in the downlink direction, that is, a downlink message is referred to as DIO. The DIO is communicated by broadcast.
A route control message transmitted in the upstream direction, that is, an upstream message is called DAO. The DAO is transmitted by unicast with the upstream station as the destination.

FIG. 3 shows a DIO format.
The format of DIO is defined in Non-Patent Document 1.
Options that are not defined in Non-Patent Document 1 can be added to the DIO.
Coverage information is stored in the DIO as an additional option.

FIG. 4 shows a format of a DODAG configuration which is one of DIO options.
DIOIntDouble. Column and DIOIntMin. A random number range is set in the column of. That is, the random number range is stored in the DIO as a configuration option.

The coverage management table 210 will be described with reference to FIG.
The coverage management table 210 is a table for managing coverage information and a random number range. The coverage management table 210 is stored in the storage unit 191.
The coverage management table 210 includes columns for a radio station, a direction, the number of stations in a coverage, a list of stations in a coverage, a first random number range, and a second random number range.
The radio station column indicates an identifier of the radio station.
The direction column indicates up or down.
The column of the number of stations in the coverage indicates the number of stations in the coverage.
The coverage internal station list column shows the coverage internal station list.
The column of the first random number range indicates a first random number range that is a random number range corresponding to the number of stations in the coverage.
The column of the second random number range indicates a second random number range that is a random number range corresponding to the coverage inner station list.
The random number range is a range of random numbers used for determining a cycle in which DIO or DAO is transmitted.
The random number range associated with the upstream station is called the upstream random number range. The uplink random number range is used to determine the period in which DAO is transmitted.
A random number range associated with a downlink station is referred to as a downlink random number range. The downlink random number range is used to determine the cycle in which the DIO is transmitted.

The coverage management table 210 of FIG. 5 is the coverage management table 210 of the wireless station # 6 in the wireless communication system 200 of FIG.
The number of in-coverage stations of own station # 6 is 4, and the in-coverage station list of own station # 6 is (# 1, # 6, # 7, # 9).

The uplink station of own station # 6 is radio station # 1.
The number of in-coverage stations of uplink station # 1 is 7, and the in-coverage station list of uplink station # 1 is (# 0, # 1, # 2, # 3, # 4, # 6, # 7).
The first random number range of uplink station # 1 is a random number range corresponding to the total number of stations in the coverage area of own station # 6 and uplink station # 1 (11 stations).
The number of overlapping stations in own station # 6 and upstream station # 1 is three (# 1, # 6, # 7).
The second random number range of uplink station # 1 is the number of stations (8 stations) obtained by subtracting the number of overlapping stations (3 stations) from the total number of stations in the coverage of own station # 6 and uplink station # 1 (11 stations). ) Is a random number range.

The downlink station of own station # 6 is radio station # 9.
The number of in-coverage stations of downlink station # 9 is 3, and the list of in-coverage stations of downlink station # 9 is (# 6, # 7, # 9).
The first random number range of the downlink station # 9 is a random number range corresponding to the total number (7 stations) of the in-coverage stations of the own station # 6 and the downlink station # 9.
The number of overlapping stations in own station # 6 and downlink station # 9 is 3 stations (# 1, # 6, # 7).
The second random number range of the downlink station # 9 is the number of stations (4 stations) obtained by subtracting the number of overlapping stations (3 stations) from the total number of stations in the coverage of the own station # 6 and the downlink station # 9 (7 stations). ) Is a random number range.

*** Explanation of operation ***
The operation of the wireless communication device 100 corresponds to a wireless communication method. The procedure of the wireless communication method corresponds to the procedure of the wireless communication program.

The operation of the master station will be described based on FIG.
FIG. 6 mainly describes the flow of operations of the master station, and details of each processing will be described later as operations of elements of the radio station.
When the master station activates the wireless function, the master station can perform wireless communication. The master station operates as follows after starting the wireless function.

In step S101, the timer unit 120 starts a DIO timer.
The DIO timer is a timer in which a DIO transmission cycle is set.
The DIO timer is called a downlink timer, and the DIO transmission cycle is called a downlink transmission cycle.

In step S102, when the DIO timer expires, the timer unit 120 detects the expiration of the DIO timer. The expiration of the timer means that the time set in the timer has elapsed. For example, a trickle timer shown in Non-Patent Document 1 is used.
If the DIO timer has expired, the process proceeds to step S103.
If the DIO timer has not expired, the process proceeds to step S111.

In step S103, the message generator 130 generates DIO, and the transmitter 193 transmits DIO by broadcasting.
After step S103, the process proceeds to step S101.

In step S111, when the DIO transmitted from the slave station reaches the antenna 906, the receiving unit 192 receives the DIO.
If the DIO is received, the process proceeds to step S300.
If the DIO has not been received, the process proceeds to step S121.

In step S300, the coverage management unit 110 updates the random number range.
After updating the random number range, the process proceeds to step S121.

In step S121, when the DAO transmitted from the slave station reaches the antenna 906, the receiving unit 192 receives the DAO.
If DAO is received, the process proceeds to step S122.
If the DAO has not been received, the process proceeds to step S102.

In step S122, the path management unit 140 registers the DAO transmission source in the path information as a downlink station.
The route information is information for registering the upstream station and the downstream station, and is stored in the storage unit 191.
After step S122, the process proceeds to step S102.

Based on FIG. 7, FIG. 8, and FIG. 9, the operation of the slave station will be described.
7 to 9 mainly describe the operation flow of the slave station, and details of each process will be described later as a process for each element of the radio station.
When the slave station activates the wireless function, the slave station can perform wireless communication. The slave station operates as follows after starting the wireless function.

In step S201 (see FIG. 7), when the DIO transmitted from the master station or another slave station reaches the antenna 906, the receiving unit 192 receives the DIO.
If the DIO is received, the process proceeds to step S300.
If the DIO has not been received, the process proceeds to step S201.

In step S300, the coverage management unit 110 updates the random number range.
After updating the random number range, the process proceeds to step S211.

  In step S211, the timer unit 120 starts the DIO timer.

In step S212, the timer unit 120 starts a DAO timer.
The DAO timer is a timer in which a DAO transmission cycle is set.
The DAO timer is called an upstream timer, and the DAO transmission cycle is called an upstream transmission cycle.

In step S221, when the DIO timer expires, the timer unit 120 detects the expiration of the DIO timer.
If the DIO timer has expired, the process proceeds to step S222.
If the DIO timer has not expired, the process proceeds to step S231.

In step S222, the message generator 130 generates DIO, and the transmitter 193 transmits DIO by broadcasting.
After step S222, the process proceeds to step S223.

  In step S223, the timer unit 120 starts the DIO timer.

In step S231, when the DAO timer expires, the timer unit 120 detects the expiration of the DAO timer.
If the DAO timer has expired, the process proceeds to step S232.
If the DAO timer has not expired, the process proceeds to step S221.

In step S232, the message generator 130 generates a DAO, and the transmitter 193 transmits the DAO to the upstream station by unicast.
After step S232, the process proceeds to step S241 (see FIG. 8).

A communication path is constructed by the processing from step S201 to step S232.
Thereafter, the processing after step S241 is executed.

In step S241 (see FIG. 8), when the DIO transmitted from the master station or another slave station reaches the antenna 906, the reception unit 192 receives the DIO.
If the DIO is received, the process proceeds to step S300.
If the DIO has not been received, the process proceeds to step S251.

In step S300, the coverage management unit 110 updates the random number range.
After updating the random number range, the process proceeds to step S242.

In step S242, the timer unit 120 determines whether the DAO timer has been started.
If the DAO timer has been started, the process proceeds to step S251.
If the DAO timer has not been started, the process proceeds to step S243.

  In step S243, the timer unit 120 starts the DAO timer.

In step S251, when the DAO transmitted from another slave station reaches the antenna 906, the receiving unit 192 receives the DAO.
If DAO is received, the process proceeds to step S252.
If the DAO has not been received, the process proceeds to step S261 (see FIG. 9).

  In step S252, the route management unit 140 registers the DAO transmission source in the route information as a downlink station.

In step S253, the timer unit 120 determines whether the DAO timer has been started.
If the DAO timer has been started, the process proceeds to step S261 (see FIG. 9).
If the DAO timer has not been started, the process proceeds to step S254.

In step S254, the timer unit 120 starts the DAO timer.
After step S254, the process proceeds to step S261 (see FIG. 9).

In step S261 (see FIG. 9), when the DIO timer expires, the timer unit 120 detects the expiration of the DIO timer.
If the DIO timer has expired, the process proceeds to step S262.
If the DIO timer has not expired, the process proceeds to step S271.

  In step S262, the message generation unit 130 generates DIO, and the transmission unit 193 transmits DIO by broadcasting.

  In step S263, the timer unit 120 starts the DIO timer.

In step S271, when the DAO timer expires, the timer unit 120 detects the expiration of the DAO timer.
If the DAO timer has expired, the process proceeds to step S272.
If the DAO timer has not expired, the process proceeds to step S241 (see FIG. 8).

In step S272, the message generator 130 generates a DAO, and the transmitter 193 transmits the DAO to the upstream station by unicast.
After step S272, the process proceeds to step S241 (see FIG. 8).

The update of the random number range (S300) will be described based on FIG.
The update of the random number range (S300) is mainly executed by the coverage management unit 110 when the DIO is received.

In step S301, the coverage management unit 110 determines whether the transmission source of the DIO is an uplink station or a downlink station.
Specifically, the coverage management unit 110 determines whether the transmission source of the DIO is a radio station registered as an uplink station in the route information or a radio station registered as a downlink station in the route information.
If the DIO transmission source is an upstream station or a downstream station, the process proceeds to step S311.
If the DIO transmission source is neither an upstream station nor a downstream station, the process proceeds to step S302.

In step S302, the coverage management unit 110 determines whether the local station is a slave station.
Specifically, attribute information indicating a master station or a slave station is stored in the storage unit 191 in advance. The coverage management unit 110 determines whether the local station is a slave station by referring to the attribute information.
If the own station is a slave station, the process proceeds to step S303.
When the own station is a master station, the random number range is not updated and the update of the random number range is completed.

In step S303, the coverage management unit 110 determines whether the uplink station is registered in the route information.
If the upstream station is not registered, the process proceeds to step S304.
If the uplink station has been registered, the random number range is not updated and the update of the random number range ends.

  In step S304, the coverage management unit 110 registers the DIO transmission source as an uplink station in the path information.

  In step S311, the coverage management unit 110 updates the number of transmission source in-coverage stations registered in the coverage management table 210 to the number of transmission source in-coverage stations set in the DIO.

  In step S312, the coverage management unit 110 updates the first random number range of the transmission source registered in the coverage management table 210.

Specifically, the coverage management unit 110 updates the first random number range of the transmission source as follows.
First, the coverage management unit 110 acquires the number of stations in the coverage area of the own station and the number of stations in the coverage area of the transmission source from the coverage management table 210.
Next, the coverage management unit 110 calculates the sum of the number of in-coverage stations of the own station and the number of in-coverage stations of the transmission source. The calculated value is referred to as the first total number of stations. The first total number of stations is expressed by the following equation.
Number of first total stations = Number of stations in coverage of own station + Number of stations in coverage of transmission source

Next, the coverage management unit 110 determines a first random number range based on the first total number of stations. The first random number range is narrower as the number of first total stations is smaller, and is wider as the number of first total stations is larger.
Then, the coverage management unit 110 updates the first random number range of the transmission source registered in the coverage management table 210 to the determined first random number range.

  After step S312, the process proceeds to step S321 (see FIG. 11).

In step S321 (see FIG. 11), the coverage management unit 110 determines whether the coverage internal station list is stored in the DIO. That is, the coverage management unit 110 determines whether there is a coverage internal station list in the DIO.
If there is a coverage internal station list in the DIO, the process proceeds to step S322.
If there is no coverage internal station list in the DIO, the process proceeds to step S331.

  In step S322, the coverage management unit 110 updates the coverage internal station list of the transmission source registered in the coverage management table 210 to the coverage internal station list set in the DIO.

  In step S323, the coverage management unit 110 updates the second random number range of the transmission source registered in the coverage management table 210.

Specifically, the coverage management unit 110 updates the second random number range of the transmission source as follows.
First, the coverage management unit 110 acquires from the coverage management table 210 the coverage in-station list of its own station and the coverage in-station list of the transmission source.
Next, the coverage management unit 110 merges the coverage in-station list of the own station and the coverage in-station list of the transmission source so that the radio stations do not overlap. As a result, a list of wireless stations existing in at least one of the coverage of the local station and the coverage of the transmission source can be obtained. The resulting list is called a merge list.
Next, the coverage management unit 110 counts radio stations included in the merge list. The number of radio stations included in the merge list is referred to as the second total station number. The second total number of stations is expressed by the following equation.
Second total number of stations = number of stations in coverage of own station + number of stations in coverage of transmission source-number of overlapping stations of own station and transmission source

Next, the coverage management unit 110 determines a second random number range based on the second total number of stations. The second random number range is narrower as the number of second total stations is smaller, and is wider as the number of second total stations is larger.
Then, the coverage management unit 110 updates the second random number range of the transmission source registered in the coverage management table 210 to the determined second random number range.

In step S331, the coverage management unit 110 determines whether the transmission source of the DIO is a downlink station.
Specifically, the coverage management unit 110 determines whether the transmission source of the DIO is a wireless station registered as a downlink station in the route information.
When the transmission source of the DIO is a downlink station, the process finishes updating the random number range.
If the source of DIO is not a downlink station, the process proceeds to step S332.

In step S332, the coverage management unit 110 calls the route management unit 140.
The route management unit 140 registers the transmission source of the DIO as the upstream station in the route information. Details will be described later.

Based on FIG. 12, the timer activation process will be described.
The timer activation process is executed by the timer unit 120 when the DIO timer or the DAO timer is activated.

  In step S <b> 401, the timer unit 120 acquires a random number range from the coverage management table 210.

Specifically, the timer unit 120 acquires the random number range as follows.
When starting the DIO timer, the timer unit 120 acquires the first random number range or the second random number range of the downlink station from the coverage management table 210.
When starting the DAO timer, the timer unit 120 acquires the first random number range or the second random number range of the uplink station from the coverage management table 210.

Specifically, the timer unit 120 acquires the first random number range or the second random number range as follows.
When the second random number range is set in the coverage management table 210, the timer unit 120 acquires the second random number range from the coverage management table 210.
When the second random number range is not set in the coverage management table 210, the timer unit 120 acquires the first random number range from the coverage management table 210.

  In step S402, the timer unit 120 calculates a transmission cycle using a random number within the random number range. The random number within the random number range means a value (random number) randomly selected from the random number range.

  The transmission cycle for the DIO timer is calculated by trickle algorithm (IETF RFC 6206) defined in Non-Patent Document 1 using a random number within a random number range.

The transmission cycle for the DAO timer is expressed by the following equation. rand {random number range} means a random number within the random number range.
Transmission cycle = rand {random number range} × unit time

  In step S403, the timer unit 120 sets a transmission cycle in the timer.

  In step S404, the timer unit 120 starts a timer.

The message generation process will be described based on FIG.
The message generation process is executed by the message generation unit 130 when DIO or DAO is generated.

In step S411, the message generation unit 130 generates a message body.
The message body is the part of the entire message excluding options.

Specifically, the message generator 130 generates a message body as follows.
When generating the DIO, the message generation unit 130 generates a message body using the DIO format.
When generating the DAO, the message generator 130 generates a message body using the DAO format.
The DIO format and the DAO format are defined in Non-Patent Document 1. The DIO format and the DAO format are stored in the storage unit 191 in advance.

If a DIO is generated, the process proceeds to step S412.
When the DAO is generated, the message generation process ends.

  In step S412, the message generation unit 130 generates an additional option for the coverage information of the local station, and adds the generated additional option to the message body.

Specifically, the message generator 130 generates an additional option for the coverage information of the local station as follows.
First, the message generation unit 130 acquires at least one of the number of stations in the coverage area of the own station and the list of coverage stations in the own station from the coverage management table 210 as the coverage information of the own station.
Then, the message generator 130 uses the additional option format to generate an additional option in which the coverage information of the local station is set. The generated additional option is an additional option for the coverage information of the local station. The format of the additional option is stored in the storage unit 191 in advance.

  In step S413, the message generation unit 130 generates a configuration option for the random number range, and adds the generated configuration option to the message body.

Specifically, the message generator 130 generates a configuration option for the random number range as follows.
First, the message generator 130 acquires the first random number range or the second random number range of the downlink station from the coverage management table 210.
Then, the message generation unit 130 generates a configuration option in which the acquired random number range is set using the configuration option format. The generated configuration option is a configuration option for the random number range. The format of the configuration option is stored in the storage unit 191 in advance.

Specifically, the message generator 130 acquires the first random number range or the second random number range as follows.
When the second random number range is set in the coverage management table 210, the message generator 130 acquires the second random number range from the coverage management table 210.
When the second random number range is not set in the coverage management table 210, the message generator 130 acquires the first random number range from the coverage management table 210.

The reception process will be described with reference to FIG.
The reception process is mainly executed by the reception unit 192 when the DIO or DAO reaches the antenna 906. DIO or DAO reaches the antenna 906 as a modulation signal.

In step S <b> 421, the reception unit 192 receives the modulated signal via the antenna 906.
In step S422, the receiving unit 192 demodulates the modulated signal. Thereby, a message is obtained.
In step S423, the receiving unit 192 outputs a message. The output message is DIO or DAO.

In step S460, the coverage management unit 110 updates the coverage information of the own station.
The update of the coverage information of the own station will be described later.

The transmission process will be described with reference to FIG.
The transmission process is executed by the transmission unit 193 when DIO or DAO is generated.

In step S431, the transmission unit 193 receives a message. The accepted message is DIO or DAO.
In step S432, the transmission unit 193 modulates the message. Thereby, a modulation signal is obtained.
In step S433, the transmission unit 193 transmits the modulated signal via the antenna 906.

Based on FIG. 16, the registration of the uplink station will be described.
The registration of the upstream station is executed by the path management unit 140 when the DIO is received.

In step S441, the path management unit 140 determines whether the uplink station is registered in the path information. That is, the path management unit 140 determines whether the uplink station has been registered.
If the upstream station has been registered, the process proceeds to step S442.
If the upstream station is not registered, the process proceeds to step S444.

In step S442, the path management unit 140 determines whether or not the uplink station update condition is satisfied.
For example, the update condition is a condition that the received power of DIO received from the transmission source is larger than the received power of DIO received from the upstream station. The update condition can be arbitrarily determined.
When the uplink station update condition is satisfied, the process proceeds to step S443.
When the update condition of the uplink station is not satisfied, the DIO transmission source is not registered as the uplink station, and the uplink station registration ends.

In step S443, the route management unit 140 updates the uplink station registered in the route information to the transmission source of the DIO.
After step S443, the update of the uplink station ends.

In step S444, the path management unit 140 registers the DIO transmission source as an upstream station in the path information.
After step S444, the update of the uplink station ends.

Based on FIG. 17, downlink station registration will be described.
The registration of the downlink station is executed by the path management unit 140 when DAO is received.

In step S451, the path management unit 140 determines whether the DAO is a message addressed to itself.
Specifically, the path management unit 140 refers to the DAO destination and determines whether the DAO destination is the local station.
If the DAO is a message addressed to the own station, the process proceeds to step S452.
When the DAO is not a message addressed to the own station, the DAO transmission source is not registered as the downlink station, and the registration of the downlink station is completed.

In step S452, the path management unit 140 determines whether the downlink station is registered in the path information. That is, the route management unit 140 determines whether the downlink station has been registered.
If the downlink station has been registered, the process proceeds to step S453.
If the downlink station is not registered, the process proceeds to step S454.

  In step S453, the path management unit 140 updates the downlink station registered in the path information to the DAO transmission source.

  In step S454, the path management unit 140 registers the DAO transmission source in the path information as a downlink station.

Based on FIG. 18, the update of own coverage information (S460) will be described.
The own coverage information update (S460) is executed by the coverage management unit 110 when DIO or DAO is received.

In step S461, the coverage management unit 110 determines whether the message transmission source is registered in the coverage-internal station list of the own station in the coverage management table 210. That is, the coverage management unit 110 determines whether the message transmission source has been registered.
When the message transmission source is already registered, the coverage information of the local station is not updated, and the update of the coverage information of the local station is completed.
If the message source is unregistered, the process proceeds to step S462.

  In step S462, the coverage management unit 110 adds 1 to the number of in-coverage stations of the own station in the coverage management table 210.

  In step S463, the coverage management unit 110 adds the transmission source of the message to the local station coverage list of the local station in the coverage management table 210.

*** Supplement of Embodiment 1 ***
In the first embodiment, the DIO storing the coverage information of the local station as an additional option is transmitted by broadcast. Thereby, the coverage information of the local station is made known to other wireless stations.
In the additional option, the coverage area list of the local station may be stored as the coverage information of the local station.
The size of the address (Prefix) indicating the station number differs depending on the system. When IPv6 is applied to the system, the size of the Prefix is 128 bits. For this reason, when the number of stations in the coverage of the own station is large, the message length of the DIO becomes too long.
Therefore, the local station may reduce the size of the Prefix by using a 16-bit short address as the Prefix.
Further, the own station divides the coverage in-station list of the own station into a plurality of times and stores it in the DIO, and informs other radio stations of the entire coverage in-station list of the own station by transmitting the DIO multiple times. Good.
In addition, the local station may generate an additional option for the local station coverage list of the local station and transmit a DIO to which the additional option for the local station coverage list of the local station is added as necessary. For example, when another wireless station requests a coverage internal station list and when its own coverage internal station list is updated, the local station has additional options for its own coverage internal station list. The added DIO is transmitted.

*** Effects of Embodiment 1 ***
The radio station can know the coverage information of the uplink station or the downlink station by receiving DIO from the uplink station or the downlink station.
The radio station can know the random number range of the uplink station by receiving DIO from the uplink station.
The own station increases or decreases the random number range in accordance with the number of stations in the coverage area of the own station in order to reduce the collision of DIOs transmitted from different coverages. Then, the local station determines a DIO transmission cycle using a random number within the random number range. Thereby, the own station can transmit DIO with a suitable transmission period based on the suitable random number range according to the number of stations in the coverage of the own station.

*** Other configurations ***
As described in Non-Patent Document 1, the slave station may quickly obtain DIO by DIS transmission.

Embodiment 2. FIG.
With respect to the form for notifying the appropriate effective period of the downlink route, differences from the first embodiment will be mainly described with reference to FIGS.

*** Explanation of configuration ***
FIG. 19 shows the format of transit information which is one of DAO options.
In the path lifetime field, the effective period of the down route is set. That is, the effective period of the downstream route is stored in the DAO as a transit option.

*** Explanation of operation ***
The reception process will be described based on FIG.
Steps S421 to S423 are as described in the first embodiment (see FIG. 14).
Step S460 is as described in the first embodiment (see FIG. 18).

In step S471, the path management unit 140 determines whether the received message is DAO.
If the received message is DAO, the process proceeds to step S472.
If the received message is DIO, the reception process ends.

In step S472, the route management unit 140 acquires the effective period of the downlink from the DAO transit option, and registers the effective period of the downlink in the route information.
When the effective period of the downlink route is already registered in the route information, the route management unit 140 updates the effective period of the downlink route registered in the route information to the effective period of the downlink route acquired from the DAO transit option. To do.

The message generation process will be described based on FIG.
Steps S411 to S413 are as described in the first embodiment (see FIG. 13).

In step S414, the message generation unit 130 determines whether the generated message is DAO.
If the generated message is DAO, the process proceeds to step S415.
If the message to be generated is DIO, the message generation process ends.

  In step S415, the message generation unit 130 generates a transit option for a valid period, and adds the generated transit option to the message body.

Specifically, the message generator 130 generates a transit option for the validity period as follows.
First, the message generation unit 130 determines a satisfaction effective period that is a period that is not insufficient as an effective period of a downlink route.
Then, the message generation unit 130 uses the transit option format to generate a transit option in which a satisfaction validity period is set. The generated transit option is a transit option for the valid period. The format of the transit option is stored in the storage unit 191 in advance.

Specifically, the message generation unit 130 determines the satisfaction validity period as follows. The satisfaction period corresponds to the number of stations in the coverage area of the own station.
First, the message generation unit 130 acquires the effective period of the downlink route from the route information.
Next, the message generation unit 130 acquires the first random number range or the second random number range of the uplink station from the coverage management table 210.
Next, the message generator 130 calculates the maximum DAO transmission period in the local station using the acquired random number range. The maximum transmission period is expressed by the following formula. The maximum random number is the maximum random number in the random number range.
Maximum transmission cycle = maximum random number × unit time

  Then, the message generator 130 adds the maximum transmission period to the effective period of the downlink. The time obtained is the satisfaction period.

*** Supplement for Embodiment 2 ***
The effective period of the downlink path determined in the own station is an effective period reflecting the number of stations in the coverage area of the uplink station, the random number range of the uplink station, and the maximum DAO transmission period in the own station.
The maximum DAO transmission period in the local station corresponds to the maximum DIO transmission period in the upstream station.

In the wireless communication system 200 of FIG. 2, when the slave station # 3 transmits DAO to the slave station # 2, the slave station # 2 is determined by the effective period of the downlink stored in the DAO, that is, the slave station # 3. The effective period of the downlink route is managed. Further, when the slave station # 2 transmits the DAO of the slave station # 3 to the master station # 0, the slave station # 2 receives the DAO in the slave station # 2 during the effective period of the downlink determined by the slave station # 3. Add the maximum transmission period of.

*** Effects of Embodiment 2 ***
The local station transmits DAO to the upstream station upon receiving DIO from the upstream station. For this reason, when the DIO transmission cycle in the upstream station increases, the effective period of the downstream path may be insufficient.
Therefore, when transmitting the DAO, the local station calculates the maximum time of the DIO transmission cycle in the upstream station, increases or decreases the effective period of the downstream path according to the calculated time, and transmits the DAO to the upstream station.

  The own station can determine an appropriate DAO transmission cycle and an appropriate effective period of the downlink path according to the number of stations in the coverage area of the own station.

  Even if the number of relays increases, the sum of the effective periods of the downlink path in each section from the master station to the slave station may be set as the effective period of the downlink path in the own station. Even if the random number range of the transmission period of DIO or DAO varies between wireless stations, it is possible to avoid a shortage of the effective period of the downlink.

Embodiment 3 FIG.
With regard to a mode for determining an appropriate transmission cycle of an application message, differences from the first embodiment and the second embodiment will be mainly described with reference to FIG.

*** Explanation of configuration ***
Based on FIG. 22, the structure of the radio | wireless communication apparatus 100 is demonstrated.
The wireless communication apparatus 100 includes an application unit 150 in addition to the software elements described in the first embodiment (see FIG. 1).
The wireless communication program causes the computer to function as the coverage management unit 110, the timer unit 120, the message generation unit 130, the path management unit 140, and the application unit 150.
The storage unit 191 stores an application executed by the application unit 150. An application means an application program.

*** Explanation of operation ***
The application unit 150 generates an application message by executing an arbitrary application.
The application message is a message generated by executing an arbitrary application, and is a message different from the route control message.

In the reception process (see FIG. 14 or FIG. 20), the reception unit 192 receives application messages in addition to DIO and DAO.
The coverage management unit 110 also updates the coverage information of its own station (S400) even when an application message is received. That is, the coverage management unit 110 registers the transmission source of the application message in its own coverage information.
Even when the application message is generated, the timer unit 120 executes timer activation processing (see FIG. 12). That is, the timer unit 120 starts an application timer. The application timer is a timer in which an application message transmission cycle is set. The application message transmission cycle is the same as the DIO transmission cycle or the DAO transmission cycle. Specifically, when the destination of the application message is a downlink station, the transmission cycle of the application message is the same as the transmission cycle of the DIO. When the destination of the application message is an upstream station, the transmission cycle of the application message is the same as the transmission cycle of DAO.
When the application timer expires, the transmission unit 193 transmits an application message.

*** Effects of Embodiment 3 ***
According to the third embodiment, the collision of application messages between different coverages can be reduced.

Embodiment 4 FIG.
The point of determining an appropriate backoff of the MAC layer message will be described mainly with respect to differences from the first to third embodiments.

*** Explanation of operation ***
The transmission unit 193 transmits the MAC layer message. The MAC layer message is a message communicated in the MAC layer. DIO, DAO and application messages are included in the MAC layer message. MAC is an abbreviation for Media Access Control.
In IEEE 802.15.4, a waiting time called back-off is defined in order to reduce the probability that a plurality of wireless stations in the same coverage transmit a MAC layer message at the same time. The back-off is expressed by the following formula. A bank-off slot is a unit time for back-off.
Backoff = Backoff slot × random number

Even before the MAC layer message is transmitted, the timer unit 120 executes timer activation processing (see FIG. 12). That is, the timer unit 120 calculates backoff and starts the MAC layer timer. The MAC layer timer is a timer for which backoff is set. The back-off is expressed by the following formula.
Back-off = back-off slot x rand {random number range}

The backoff of the MAC layer message to the uplink station is calculated using the random number range of the uplink station. The backoff calculated using the random number range of the upstream station is called upstream backoff.
The back-off of the MAC layer message to the downlink station is calculated using the random number range of the downlink station. The backoff calculated using the random number range of the downlink station is called downlink backoff.

  When the MAC layer timer expires, the transmission unit 193 transmits a MAC layer message.

*** Effects of Embodiment 4 ***
The probability that MAC layer messages are simultaneously transmitted from different coverages to the same coverage can be reduced, and collision of MAC layer messages can be reduced.

Embodiment 5. FIG.
A mode for avoiding the construction of a communication path in which two wireless stations are in a state of hidden terminal will be described mainly based on FIG. 23 with respect to differences from the first to fourth embodiments.

*** Explanation of configuration ***
Based on FIG. 23, the structure of the radio | wireless communication apparatus 100 is demonstrated.
The wireless communication apparatus 100 includes a hidden control unit 160 in addition to the software elements described in the first embodiment (see FIG. 1). Furthermore, the wireless communication device 100 may include the application unit 150 described in the third embodiment (see FIG. 22).
The wireless communication program causes the computer to function as the coverage management unit 110, the timer unit 120, the message generation unit 130, the path management unit 140 (the application unit 150), and the hidden control unit 160.

*** Explanation of operation ***
The reception process will be described based on FIG.
Steps S471 and S472 described in the second embodiment (see FIG. 20) may be added to the reception process.

  Step S421 is as described in the first embodiment (see FIG. 14).

In step S480, the receiving unit 192 measures the power of the received modulated signal. The measured power is called the received power of the transmission source.
The hidden control unit 160 stores the received power of the transmission source in the storage unit 191. Specifically, the hidden control unit 160 stores the received power of the transmission source in the storage unit 191 in association with the station number of the transmission source.

Steps S422 and S423 are as described in the first embodiment (see FIG. 14).
Step S460 is as described in the first embodiment (see FIG. 18).

In step S481, the hidden control unit 160 determines whether the received message is DAO.
If the received message is DAO, the process proceeds to step S482.
If the received message is not DAO, the reception process ends.

  In step S482, the hidden control unit 160 compares the received power sum of the uplink station and the transmission source with a power threshold value.

Specifically, the hidden control unit 160 operates as follows.
First, the hidden control unit 160 acquires the received power of the uplink station and the received power of the transmission source from the storage unit 191. The received power of the upstream station is the received power of DIO from the upstream station, and the received power of the transmission source is the received power of DAO from the transmission source.
Next, the hidden control unit 160 calculates the sum of the received power of the uplink station and the received power of the transmission source. The calculated sum is the received power sum.
Then, the hidden control unit 160 compares the received power sum with the power threshold value. The power threshold is a predetermined value.
If the received power sum exceeds the power threshold, the process proceeds to step S483.
If the received power sum is less than or equal to the power threshold, the reception process ends.

In step S483, the hidden control unit 160 rejects the DAO request.
Specifically, the hidden control unit 160 generates a DAO-ACK message indicating rejection. Then, the transmission unit 193 transmits a DAO-ACK message. The DAO-ACK message is a response message to DAO. The rejection of the request by DAO means the rejection of becoming an upstream station, that is, the rejection of path construction.

*** Effect of Embodiment 5 ***
The outline and effects of the fifth embodiment will be described by taking the relationship among the slave station # 1, the slave station # 7, and the master station # 0 in the wireless communication system 200 of FIG.
When the sum of the received powers of the master station # 0 and the slave station # 7, which are the in-coverage stations of the slave station # 1, exceeds the threshold, the slave station # 1 has a relationship between the master station # 0 and the slave station # 7. Estimated to be in a hidden terminal relationship.
The hidden terminal relationship is a relationship in which two wireless stations are not in-coverage stations of each other.

Specifically, slave station # 1 receives DAO from slave station # 7, and the sum of the received power of DAO from slave station # 7 and the received power of DIO from master station # 0 exceeds the threshold value. Judgment is made.
When the sum of the received powers exceeds the threshold value, the slave station # 1 indicates a refusal to DAO by a DAO-ACK message to the slave station # 7.

The slave station # 7 abandons the path construction with the slave station # 1, searches for another path, and constructs a detour path.
As a result, the slave station # 7 can avoid building a communication path that is in a hidden terminal relationship with the master station # 0 across the slave station # 1.

*** Other configurations ***
Whether or not there is a hidden terminal relationship may be determined based on the message transmission success rate instead of the received power.

*** Effect of the embodiment ***
The radio station can appropriately determine the transmission period of DIO according to the number of stations in the coverage. As a result, it is not necessary to take an unnecessarily long time for detecting an abnormality in the upstream path.
The downlink station can know the maximum value of the DIO transmission cycle of the uplink station by receiving the DIO. Therefore, the downlink station can determine an effective period of the downlink path appropriate for the transmission period of the DIO of the uplink station. As a result, it is not necessary to take a longer time than necessary to detect an abnormality in the downstream path.
Since uplink station is notified by DIO number in station coverage, the own station, depending on the total number in the station of the coverage of the upper Ri station and the own station, to properly determine the random number range of the transmission cycle of DAO it can.
Since the random number range of the DAO transmission cycle is optimally determined, the probability that a plurality of DAOs arriving from a plurality of coverages collide at the same radio station can be reduced.
Also in the transmission of application messages, it is possible to reduce the probability that a plurality of application messages arriving from a plurality of coverages collide at the same radio station.

*** Supplement to the embodiment ***
In the embodiment, the function of the wireless communication device 100 may be realized by hardware.
FIG. 25 shows a configuration when the function of the wireless communication apparatus 100 is realized by hardware.
The wireless communication device 100 includes a processing circuit 990. The processing circuit 990 is also called a processing circuit.
The processing circuit 990 is a dedicated electronic circuit that implements the coverage management unit 110, the timer unit 120, the message generation unit 130, the path management unit 140, the application unit 150, the hidden control unit 160, and the storage unit 191.
For example, the processing circuit 990 is a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, a logic IC, GA, ASIC, FPGA, or a combination thereof. GA is an abbreviation for Gate Array, ASIC is an abbreviation for Application Specific Integrated Circuit, and FPGA is an abbreviation for Field Programmable Gate Array.

  The wireless communication device 100 may include a plurality of processing circuits that replace the processing circuit 990. The plurality of processing circuits share the role of the processing circuit 990.

  The embodiments are exemplifications of preferred forms and are not intended to limit the technical scope of the present invention. The embodiment may be implemented partially or in combination with other embodiments. The procedure described using the flowchart and the like may be changed as appropriate.

  100 wireless communication device, 110 coverage management unit, 120 timer unit, 130 message generation unit, 140 route management unit, 150 application unit, 160 hidden control unit, 191 storage unit, 192 reception unit, 193 transmission unit, 200 wireless communication system, 210 Coverage management table, 901 processor, 902 memory, 903 auxiliary storage device, 904 RF circuit, 905 PHY control circuit, 906 antenna, 907 oscillator, 990 processing circuit.

Claims (5)

A wireless communication device that operates as one of the wireless stations,
Self-coverage information that is at least one of the number of radio stations and a list of radio stations for radio stations existing within the coverage of the local station, and a downlink station that is one of the radio stations existing within the coverage of the local station Downlink coverage information that is at least one of the number of radio stations and a list of radio stations for radio stations existing in the coverage of the mobile station, and the coverage of the upstream station that is one of the radio stations existing in the coverage of the local station A storage unit that stores uplink coverage information that is at least one of the number of radio stations and the radio station list for radio stations existing in
A receiving unit for receiving a downstream message and an upstream message;
A coverage management unit for storing, in the storage unit, uplink coverage information included in the received downlink message when a downlink message is received;
When a downlink message is received, a downlink timer with a downlink transmission cycle is started. When an downlink message is received and when an uplink message is received, an uplink timer with an uplink transmission cycle is started. A timer section to
A transmission unit that transmits a downlink message including self-coverage information stored in the storage unit when the downlink timer expires, and a transmission unit that transmits an uplink message when the uplink timer expires,
The coverage management unit determines an uplink random number range based on the own coverage information and the uplink coverage information, determines a downlink random number range based on the own coverage information and the downlink coverage information,
The radio communication apparatus, wherein the timer unit calculates the uplink transmission cycle using a random number selected from the uplink random number range, and calculates the downlink transmission cycle using a random number selected from the downlink random number range. The wireless communication device includes a message generation unit that generates a message,
The uplink message includes a valid period of the downlink route,
The message generation unit calculates a maximum transmission period using the uplink random number range, calculates a satisfaction effective period by adding the maximum transmission period to an effective period of a downlink path included in the uplink message, and the satisfaction effective period A message containing
The wireless communication apparatus according to claim 1, wherein the transmission unit transmits a message including the satisfaction validity period. The timer unit starts an application timer in which the uplink transmission cycle or the downlink transmission cycle is set,
The wireless communication apparatus according to claim 1, wherein the transmission unit transmits an application message when the application timer expires. The timer unit calculates a backoff using the upstream random number range or the downstream random number range, and starts a MAC layer timer in which the backoff is set,
The wireless communication apparatus according to claim 1, wherein the transmission unit transmits a MAC layer message when the MAC layer timer expires. The wireless communication device includes a hidden control unit that rejects a request by the uplink message,
The wireless communication apparatus according to claim 1, wherein the hidden control unit rejects a request by the uplink message when a sum of reception power of the uplink message and reception power of the downlink message exceeds a power threshold.

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