JP2022131321A - Communication system and position estimation method - Google Patents

Abstract

To provide a communication system and a position estimation method that can estimate the position of a wireless communication device without being hindered by obstacles in a wireless section.SOLUTION: There is provided a communication system 100 comprising a gateway device 1, a base station 2 and a plurality of wireless communication devices 31 to 3n where at least one wireless communication device of the plurality of wireless communication devices relays and forwards a signal so that data is transmitted and received between the base station and the wireless communication devices. The wireless communication devices comprise one or more first wireless communication devices deployed fixedly and one or more second wireless communication devices each deployed on a mobile body. The base station estimates a position of a given second wireless communication device based on position information of one of the plurality of first communication devices which is the closest to the given second wireless communication device.SELECTED DRAWING: Figure 1

Description

The present invention relates to a communication system and a position estimation method for estimating the position of a node located in a mobile body.

Conventionally, in a communication system composed of wireless communication devices using a multi-hop method, in a free space where there are no obstacles in the wireless section, the position of the wireless communication device is calculated by calculating the estimated distance using the radio wave intensity. can be estimated. Moreover, in such a communication system, it is also possible to estimate the position of a wireless communication device based on the number of multi-hops (see Patent Document 1, for example).

WO2014/013578

However, when there is an obstacle in the wireless section such as in an urban area or a construction site, the estimated distance cannot be calculated appropriately using the radio wave intensity due to the influence of radio wave reflection and the like. Therefore, it was difficult to estimate the position of the wireless communication device. In addition, even when estimating the position of a wireless communication device based on the number of multi-hops, it is difficult to estimate the position of the wireless communication device in special environments such as tunnels and construction sites due to radio reflections. rice field.

Therefore, there is a demand for a communication system and a position estimation method capable of estimating the position of a wireless communication device even when an obstacle exists in the wireless section.

A communication system according to the present invention includes a base station and a plurality of wireless communication devices, wherein at least one of the plurality of wireless communication devices relays and transfers a signal, A communication system for transmitting and receiving data to and from a device, wherein the wireless communication device includes one or more first wireless communication devices arranged in a fixed manner and one or more first wireless communication devices arranged in a mobile body. and a second wireless communication device, wherein the base station provides location information of a first wireless communication device closest to a predetermined second wireless communication device among one or more of the first wireless communication devices. , the position of the predetermined second wireless communication device is estimated.

Also, a position estimation method according to the present invention includes a base station, one or more first wireless communication devices that are fixedly arranged, and one or more second wireless communication devices that are arranged on a mobile object. a plurality of wireless communication devices, wherein at least one wireless communication device of the plurality of wireless communication devices relays and transfers signals, and transmits and receives data between the base station and the wireless communication device; A position estimation method for a communication system, comprising: based on position information of a first wireless communication device closest to a predetermined second wireless communication device among one or more first wireless communication devices, the predetermined to estimate the position of the second wireless communication device.

As described above, according to the present invention, the position of the second wireless communication device placed on the mobile object is estimated based on the position information of the first wireless communication device fixedly placed. Therefore, the position of the wireless communication device can be estimated even when an obstacle exists in the wireless section.

1 is a block diagram showing an example of a configuration of a communication system according to Embodiment 1; FIG. 2 is a block diagram showing an example of the configuration of the GW device in FIG. 1; FIG. 2 is a block diagram showing an example of the configuration of a base station in FIG. 1; FIG. 4 is a functional block diagram showing an example of a configuration of a CPU in FIG. 3; FIG. 2 is a block diagram showing an example of the configuration of the wireless communication device of FIG. 1; FIG. 6 is a functional block diagram showing an example of a configuration of a CPU in FIG. 5; FIG. FIG. 4 is a schematic diagram for explaining costs between nodes; 8 is a schematic diagram showing an example of a routing table of node c shown in FIG. 7; FIG. FIG. 4 is a schematic diagram for explaining switch definition information; 7 is a flow chart showing an example of the flow of address setting processing by the wireless communication device of the communication system according to Embodiment 1; 7 is a flow chart showing an example of the flow of radio wave intensity information acquisition processing by the wireless communication device of the communication system according to Embodiment 1; 4 is a flowchart showing an example of the flow of position estimation processing by a base station of the communication system according to Embodiment 1;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to the following embodiments, and various modifications can be made without departing from the gist of the present invention. In addition, the present invention includes all possible combinations of the configurations shown in the following embodiments. Also, in each figure, the same reference numerals denote the same or corresponding parts, which are common throughout the specification.

Embodiment 1.
A communication system according to the first embodiment will be described.

[Configuration of communication system 100]
FIG. 1 is a block diagram showing an example of the configuration of a communication system according to the first embodiment. As shown in FIG. 1, a communication system 100 includes a gateway device (hereinafter referred to as "GW device") 1, a base station 2, and a plurality of wireless communication devices 3 ₁ to 3 _n (n is an integer of 2 or more). ) and

The GW device 1 is one of host devices in this communication system 100, and is connected to host devices (not shown) including the GW device 1 via a network (not shown). The GW device 1 communicates with the base station 2 using, for example, TCP/IP (Transmission Control Protocol/Internet Protocol) as a communication protocol. Serial communication is used as communication between the GW device 1 and the base station 2 .

The base station 2 is a master station device for the wireless communication devices 3 ₁ to 3 _n , and relays communication between the wireless communication devices 3 ₁ to 3 _n and the host device. The base station 2 and the wireless communication devices 3 ₁ to 3 _n communicate using, for example, a short-range wireless communication protocol whose basic specifications are defined by the wireless communication standard IEEE (Institute of Electrical and Electronic Engineers) 802.15.4. . When the GW device 1 notifies the information for the GW device 1 to communicate with the wireless communication devices 3 ₁ to 3 _n by wire, the base station 2 wirelessly transmits this information to each of the wireless communication devices 3 ₁ to 3 _n . It is responsible for performing media conversions to notify the

The wireless communication devices 3 ₁ to 3 _n are sensor units that acquire various types of information about the positions of their own devices as sensor information, for example, by sensors. Each of the wireless communication devices 3 ₁ to 3 _n communicates with the base station 2 using a multi-hop method of indirectly communicating with a communication target device using another wireless communication device as a relay. . The wireless communication devices 3 ₁ to 3 _n are units driven by, for example, a battery as a power supply, and periodically transmit packets containing acquired sensor information to the GW device 1 via the base station 2. .

(GW device 1)
FIG. 2 is a block diagram showing an example of the configuration of the GW device in FIG. As shown in FIG. 2, the GW device 1 includes a CPU (Central Processing Unit) 11, a RAM (Random Access Memory) 12, a flash memory 13, a maintenance communication unit 14, an external output communication unit 15, and a GW-side wired communication unit. 16.

The flash memory 13 is a nonvolatile memory, and stores BOOT, which is a basic program to be executed by the CPU 11 when the GW device 1 is started, and various programs. The CPU 11 executes various types of processing such as arithmetic processing according to programs stored in the flash memory 13 . The RAM 12 stores programs read from the flash memory 13 when the CPU 11 executes the programs. In addition, the RAM 12 stores calculation results when the CPU 11 performs calculation processing.

The maintenance communication unit 14 is a communication interface to which a maintenance PC (Personal Computer) is connected during debugging. The external output communication unit 15 is a communication interface used when outputting to an external device or the like. The external output communication unit 15 is, for example, a serial port. The GW-side wired communication unit 16 is a communication interface for communicating with the base station 2 . The GW-side wired communication unit 16 is, for example, a USB (Universal Serial Bus) port.

(Base station 2)
3 is a block diagram showing an example of the configuration of the base station in FIG. 1. FIG. As shown in FIG. 3, the base station 2 includes a CPU 21, a RAM 22, a flash memory 23, a first wireless communication section 24, an external output communication section 25, and a base station side wired communication section .

The flash memory 23 is a nonvolatile memory, and stores BOOT, which is a basic program to be executed by the CPU 21 when the base station 2 is activated, and various programs. The CPU 21 executes various types of processing such as arithmetic processing according to programs stored in the flash memory 23 . The functions and specific processing of the CPU 21 will be described later.

The RAM 22 stores programs read from the flash memory 23 when the CPU 21 executes the programs. Also, the RAM 22 stores the calculation result when the CPU 21 performs the calculation process. For example, in the first embodiment, the RAM 22 stores the maximum intensity set as the maximum among the radio wave intensity information acquired from the wireless communication devices 3 ₁ to 3 _n . The RAM 22 also stores a threshold for radio field intensity information acquired from each node. The threshold is set to "-90 dB", for example.

The first wireless communication unit 24 is a communication interface used when communicating with the wireless communication devices 3 ₁ to 3 _n . The first wireless communication unit 24 transmits downlink packets directly to a predetermined wireless communication device or indirectly via another wireless communication device. Also, the first wireless communication unit 24 receives upstream packets directly from a predetermined wireless communication device or indirectly via another wireless communication device.

The external output communication unit 25 is a communication interface used when outputting to an external device or the like. The external output communication unit 25 is, for example, a serial port. The base station side wired communication unit 26 is a communication interface for communicating with the GW device 1 . The base station side wired communication unit 26 is, for example, a USB port.

(CPU 21)
FIG. 4 is a functional block diagram showing an example of the configuration of the CPU in FIG. 3; As shown in FIG. 4 , the CPU 21 has a list collecting section 211 , a determining section 212 , a parameter setting section 213 and a transmission/reception processing section 214 . Note that only the configuration for executing the functions according to the first embodiment is shown here, and the description of other configurations is omitted.

The list collection unit 211 collects and updates the connection list based on control packets, which are broadcast frames periodically transmitted from the wireless communication devices 3 ₁ to 3 _n , which are respective nodes, to the base station 2 . The connection list is for managing nodes that can communicate with the base station 2 . In Embodiment 1, the connection list includes wireless communication devices capable of communicating with the base station 2 among the wireless communication devices 3 ₁ to 3 _n .

Specifically, the list collection unit 211 receives a request for connection from the wireless communication devices 3 ₁ to 3 _n , which are nodes, to the base station 2, and the base station 2 authenticates the request. add the wireless communication device to the connection list. In addition, when control packets that are periodically transmitted from each wireless communication device to the base station 2 are not transmitted for a certain period of time, the list collection unit 211 deletes the node from the connection list.

The determination unit 212 performs various determinations performed during processing by the base station 2 . In Embodiment 1, the determination unit 212 determines whether or not the addresses of the wireless communication devices 3 ₁ to 3 _n are fixed addresses. A fixed address is an address that is fixedly assigned to a node, and indicates that the node is fixedly arranged. That is, when the addresses of the wireless communication devices 3 ₁ to 3 _n are fixed addresses, the determination unit 212 can determine that the wireless communication devices are fixedly arranged. Further, when the wireless communication device 3 ₁ to 3 _n addresses are not fixed addresses, the determination unit 212 can determine that the wireless communication device is located in a mobile object.

The determining unit 212 also determines whether or not a response to the measurement packet transmitted to the wireless communication devices 3 ₁ to 3 _n has been received, and the validity of the radio wave intensity obtained based on the received response. Furthermore, the determination unit 212 compares the maximum intensity of radio waves and the acquired intensity of radio waves, and determines which value is greater. A measurement packet is a signal transmitted to the wireless communication devices 3 ₁ to 3 _n in order to measure the radio field intensity of the wireless communication devices 3 ₁ to 3 _n .

A determination as to whether the radio wave intensity is valid is made, for example, based on the magnitude of the acquired radio wave intensity. This is because when the radio wave intensity is weak, the received radio waves are considered to be due to errors such as reflection. In this case, the determination unit 212 compares the threshold for the radio wave intensity stored in the RAM 22 with the acquired radio wave intensity, and determines the validity of the radio wave intensity based on the comparison result.

The parameter setting unit 213 sets various parameters such as the table index i and the maximum strength of radio waves. The table index i is a parameter used when confirming the radio wave intensity of each wireless communication device 3 ₁ to 3 _n . The transmission/reception processor 214 transmits measurement packets to the wireless communication devices 3 ₁ to 3 _n and receives responses to the measurement packets from the wireless communication devices 3 ₁ to 3 _n .

(Wireless communication devices 3 ₁ to 3 _n )
FIG. 5 is a block diagram showing an example of the configuration of the wireless communication device of FIG. 1. As shown in FIG. Since the wireless communication devices 3 ₁ to 3 _n have the same configuration, the configuration of the wireless communication device 3 ₁ will be explained here. As shown in FIG. 5 , the wireless communication device 31 includes _a CPU 31 , RAM 32 , flash memory 33 , second wireless communication section 34 , external output communication section 35 , sensor 36 and switch 37 .

The flash memory 33 is a nonvolatile memory, and stores BOOT, which is _a basic program to be executed by the CPU 31 when the wireless communication device 31 is started, and various programs. The CPU 31 executes various types of processing such as arithmetic processing according to programs stored in the flash memory 33 . The functions and specific processing of the CPU 31 will be described later.

The RAM 32 stores programs read from the flash memory 33 when the CPU 31 executes the programs. Also, the RAM 32 stores the calculation result when the CPU 31 performs the calculation process. The RAM 32 also stores switch numbers of the switches 37 and switch definition information that associates switch numbers with operations. Details of the switch definition information will be described later.

The second radio communication unit 34 is a communication interface used when communicating with the base station 2 or the radio communication devices 3 ₂ to 3 _n . The second radio communication unit 34 receives a downlink packet sent from a host device such as the GW device 1 to its own device via the base station 2 or one of the other radio communication devices 3 ₂ to 3 _n . do. Also, the second radio communication unit 34 transmits uplink packets to host devices such as the GW device 1 via the base station 2 or other radio communication devices 3 ₂ to 3 _n . For example, the second wireless communication unit 34 periodically transmits control packets, which are broadcast frames.

The external output communication unit 35 is a communication interface used for external output. _The sensor 36 detects various states in the wireless communication device 31 and outputs sensor information indicating the detection results. As the sensor 36, for example, a temperature sensor that detects temperature, a humidity sensor that detects humidity, a water immersion sensor that detects water immersion, an acceleration sensor that detects vibration, and the like are used.

The switch 37 can be set to a plurality of states. In Embodiment 1, the switch 37 is provided for setting the number of the device itself, and the number is set by the user. The set number is unique to each of the wireless communication devices 3 ₁ to 3 _n , and the switch 37 supplies the CPU 31 with the switch number indicating the set number. A rotary switch, for example, is used as the switch 37 .

(CPU 31)
6 is a functional block diagram showing an example of the configuration of the CPU in FIG. 5. FIG. As shown in FIG. 6 , the CPU 31 has a switch setting acquisition section 311 , a switch number determination section 312 , an information acquisition section 313 , an address setting section 314 and a transmission/reception processing section 315 . Note that only the configuration for executing the functions according to the first embodiment is shown here, and the description of other configurations is omitted.

The switch setting acquisition unit 311 acquires the switch number set in the switch 37 and stores the acquired switch number in the RAM 32 . The switch number determination unit 312 determines whether or not the switch number is 0 during address setting processing and radio wave intensity information acquisition processing, which will be described later.

The information acquisition unit 313 acquires various types of information such as information received from the outside or information obtained by the sensor 36 or the like of the device itself. In Embodiment 1, the information acquisition unit 313 acquires radio wave intensity information indicating the radio wave intensity of another wireless communication device based on a control packet received from another wireless communication device.

The address setting unit 314 sets the address of its own device based on the result of determination by the switch number determination unit 312 . The transmission/reception processing unit 315 performs processing for transmitting the radio wave intensity information acquired by the information acquisition unit 313 to the base station 2 via the second wireless communication unit 34 .

[Operation of communication system 100]
The operation of communication system 100 according to the first embodiment will be described. First, basic communication operations between the base station 2 and the wireless communication devices 3 ₁ to 3 _n in the communication system 100 will be described.

(basic action)
For example, when the wireless communication devices 3 ₁ to 3 _n communicate using the multi-hop method defined by the wireless communication standard IEEE802.15.4, the base station 2 periodically communicates between the wireless communication devices. Uplink communication routes from the wireless communication devices 3 ₁ to 3 _n are determined based on the route information. The radio communication devices 3 ₁ to 3 _n transmit data to the GW device 1, which is a host device, using the upstream communication path determined by the base station 2. FIG. The GW device 1 uses the downstream communication path to transmit control packets including control information regarding settings to the wireless communication devices 3 ₁ to 3 _n via the base station 2 .

(Determination of communication route)
Here, a method of determining a communication route by the communication system 100 will be described. FIG. 7 is a schematic diagram for explaining costs between nodes. FIG. 7 shows link costs between nodes in a plurality of nodes a to g. A link cost is a cost determined by the strength of radio waves with other nodes located in the vicinity of a certain node, and is indicated, for example, by three-level values from "1" to "3". A smaller link cost value indicates a shorter distance.

FIG. 8 is a schematic diagram showing an example of a routing table of node c shown in FIG. In FIG. 8, node a corresponds to the base station 2 in the first embodiment, and nodes b to g correspond to the wireless communication devices 3 ₁ to 3 _n .

In the routing table of FIG. 8, the item "destination" indicates a node to which node c sends a packet and which is the parent of node c. The item "link cost" indicates the cost for other nodes located around node c, as described above. The item “path cost” indicates the cost from the destination node to the node a corresponding to the GW device 1 . In this example, the value of the path cost is the sum of the cost values from the destination node of node c to node a.

The item "parent" indicates a node that is the parent of the node described in the item "destination". The item "fixed connection" indicates a node that is forcibly selected as a parent regardless of the link cost and path cost values. The node with the number set by the switch 37 is selected for the fixed connection. In the example shown in FIG. 8, considering the link cost and path cost, node b is desirable as the destination (parent) of node c.

In a typical communication system, the node with the superior path cost is selected as the parent. On the other hand, in the communication system 100 according to the first embodiment, the fixed connection is set by the switch 37, and the parent designated by the fixed connection is selected.

(switch definition information)
FIG. 9 is a schematic diagram for explaining switch definition information. In FIG. 9, the switch numbers and operations of the switches 37 are associated with each other. In the switch definition information, the item “switch number” indicates the number set for the switch 37 . Note that the numbers are in hexadecimal notation. The item "operation" indicates the operation when the switch 37 is set to the corresponding switch number.

For example, when the switch number is set to "0", the corresponding wireless communication device operates as "no fixed connection". That is, the wireless communication device operates as a mobile wireless communication device. Also, when the switch number is set to "1", the corresponding wireless communication device operates as if it is fixedly arranged with the GW device 1 as the parent. Furthermore, when the switch number is set to "2" to "F", the corresponding wireless communication device uses the switch number as a fixed address and operates as if it is fixedly arranged.

Specifically, for example, the wireless communication devices placed at predetermined intervals in a tunnel or the wireless communication devices placed on each floor of a building have the switch number "2" of the switch 37 so as to establish a fixed connection. ~ is set to "F". In addition, the switch number of the switch 37 is set to "0", which is "no fixed connection", for the wireless communication device placed on a moving person or a heavy machine.

When the switch numbers are set to "2" to "F", the corresponding wireless communication devices are assigned addresses "0x0002" to "0x000F" corresponding to the switch numbers as fixed addresses and are fixedly arranged. works as a thing. Note that "0x" indicates that the value of the address is in hexadecimal notation. Also, when the switch number is set to "0", the corresponding wireless communication device is assigned any one of the addresses "0x0010" to "0xFFFE" and operates as if it is located in a mobile unit. These addresses are assigned by the base station 2 based on the MAC address or the like of the wireless communication device.

(Position estimation of wireless communication devices 3 ₁ to 3 _n )
Position estimation of the wireless communication devices 3 ₁ to 3 _n by the communication system 100 according to the first embodiment will be described. In the communication system 100 according to the first embodiment, the base station 2 is a radio communication device that is not fixedly arranged and is arranged on a moving object such as a person or a heavy machine among the radio communication devices 3 ₁ to 3 _n . , a measurement packet for measuring the radio wave intensity is transmitted. Then, the base station 2 receives a response to the measurement packet from the mobile wireless communication device, and estimates the position of the mobile wireless communication device based on the received measurement packet response.

At this time, the wireless communication device of the mobile device transmits a packet containing the radio field strength between itself and the wireless communication device fixedly arranged closest to itself to the base station 2 as a response to the measurement packet. .

In order to perform such operations, the wireless communication devices 3 ₁ to 3 _n according to the first embodiment perform address setting processing and radio wave intensity information acquisition processing, which will be described below. Further, the base station 2 performs position estimation processing described below.

(Address setting process by wireless communication devices 3 ₁ to 3 _n )
FIG. 10 is a flowchart showing an example of the flow of address setting processing by the wireless communication device of the communication system according to the first embodiment. Here, the operation of the wireless communication device 31 will be described as _an example. The address setting process is a process for setting whether each wireless communication device 3 ₁ to 3 _n is fixedly arranged or arranged in a mobile body.

_First , when the wireless communication device 31 is activated in step S1, the switch setting acquisition unit 311 of the CPU 31 reads the switch number set in the switch 37 from the RAM 32 in step S2.

Next, in step S3, the switch number determination unit 312 determines whether or not the read switch number is zero. If the switch number is other than 0 (step S3: YES), the address setting unit 314 sets the read switch number as a fixed address in step S4. On the other hand, if the switch number is 0 (step S3: NO), the address setting unit 314 sets the address of the device to "no fixed address" in step S5.

Thus, the wireless communication device 31 _sets its own address based on the setting of the switch 37 . That is, the wireless communication device 31 is set with a “fixed address” when the device is installed in a moving object such as a person or a heavy machine, and is set with an address other than the fixed address when it is fixedly installed.

(Processing for acquiring radio wave intensity information by wireless communication devices 3 ₁ to 3 _n )
FIG. 11 is a flowchart showing an example of the flow of radio wave intensity information acquisition processing by the wireless communication device of the communication system according to the first embodiment. Here, the operation of the wireless communication device 31 will be described as _an example. The radio wave intensity information acquisition process is a process for acquiring radio wave intensity information indicating the radio wave intensity with respect to another fixedly placed wireless communication device when the own device is placed in a mobile object.

First, in step S<b>11 , the wireless communication device 31 receives the measurement packet transmitted from the base station ₂ via the second wireless communication unit 34 . In step S12, the switch number determination unit 312 of the CPU 31 determines whether or not the switch number of its own device read from the RAM 32 is zero. If the switch number is 0 (step S12: YES), the information acquisition unit 313 acquires the radio wave intensity information of its own device in step S13. Then, the transmission/reception processing unit 315 transmits the acquired radio wave intensity information to the base station 2 via the second wireless communication unit 34 as a response to the received measurement packet. On the other hand, if the switch number is other than 0 (step S12: NO), the series of processing ends.

In this way, when the wireless communication device 31 receives a measurement packet from the base station ₂ and does not have a fixed address set as its own address, the wireless communication device 31 responds to the radio field intensity measurement request from the base station 2. to measure the signal strength. Then, the wireless communication device 31 transmits the radio wave intensity, which is the measurement result, to the base station ₂ .

(Position estimation processing by base station 2)
FIG. 12 is a flowchart showing an example of the flow of position estimation processing by the base station of the communication system according to the first embodiment. Position estimation processing is processing for estimating the position of a mobile radio communication device based on the position information of a fixedly arranged radio communication device and the radio wave intensity for that radio communication device.

First, in step S21, the list collection unit 211 of the CPU 21 collects the currently connected connection list. In step S22, the determination unit 212 determines whether or not the following steps S23 to S32 have been completed for all the wireless communication devices 3 ₁ to 3 _n in the connection list. If the processing for all the wireless communication devices 3 ₁ to 3 _n has not been completed (step S22: NO), the processing moves to step S23. When the processing for all the wireless communication devices 3 ₁ to 3 _n is completed (step S22: YES), the series of processing is completed.

In step S23, the determination unit 212 determines whether or not the address of the target wireless communication device in the connection list is an address that does not allow fixed connection. If the address of the target wireless communication device is an address that is not fixedly connected (step S23: YES), the transmission/reception processing unit 214 sends the measurement packet to this wireless communication device via the first wireless communication unit 24 in step S24. to send. On the other hand, if the address of the target wireless communication device is not an address that is not fixedly connected, that is, if it is a fixed address (step S23: NO), the process proceeds to step S33.

In step S25, the determination unit 212 determines whether or not a response to the transmitted measurement packet has been received. If a response to the measurement packet is received (step S25: YES), the parameter setting unit 213 initializes the fixed address table index i and the maximum radio wave intensity in step S26. In this case, the parameter setting unit 213 sets the value of the table index i to "1" and the value of the maximum strength to "0". Moreover, when the response to the measurement packet is not received (step S25: NO), the process proceeds to step S31.

In step S27, the determination unit 212 determines whether or not the radio field intensity acquired as a response to the measurement packet is valid. If the acquired radio wave intensity is valid (step S27: YES), the parameter setting unit 213 sets the acquired radio wave intensity as the acquired intensity in step S28. Moreover, when the acquired radio wave intensity is invalid (step S27: NO), the process proceeds to step S31.

In step S<b>29 , the determination unit 212 compares the maximum intensity of radio waves stored in the RAM 22 with the obtained intensity. As a result of the comparison, if the acquired intensity is greater than the maximum intensity (step S29: YES), the parameter setting unit 213 updates the maximum intensity with the acquired intensity in step S30. Also, based on the value of the table index i, the parameter setting unit 213 holds the location information of the wireless communication device fixedly arranged at the closest location to the responding wireless communication device. The location information can be determined based on the fixed address of the switch number corresponding to the value of table index i. On the other hand, if the obtained intensity is equal to or less than the maximum intensity (step S29: NO), the process proceeds to step S31.

In step S31, the CPU 21 increments the value of the table index i by one. In step S32, the determination unit 212 determines whether the value of the table index i is the maximum value. When the value of the table index i is the maximum value (step S32: YES), the CPU 21 changes the connection list to the next list in step S33. Then, the process returns to step S22. Moreover, when the value of the table index i is not the maximum value (step S32: NO), the process returns to step S27.

The processing from step S22 to step S32 is repeated by the number of collected connection lists. As a result, the wireless communication device with the fixed address having the highest radio wave intensity is searched for among the wireless communication devices 3 ₁ to 3 _n .

In this way, the base station 2 transmits measurement packets to the wireless communication devices located on the mobile unit among the wireless communication devices 3 ₁ to 3 _n , and receives responses to the measurement packets. Then, the base station 2 acquires the location information of the fixed wireless communication device closest to the wireless communication device that returned the response and the radio field intensity information for the wireless communication device included in the received response. This allows the base station 2 to estimate the position of the mobile wireless communication device that returned the response.

As described above, in the communication system 100 according to the first embodiment, the base station 2 is the second radio communication device arranged in a predetermined mobile unit among the first radio communication devices arranged in a fixed manner. A position of the second wireless communication device is estimated based on the position information of the first wireless communication device closest to the device. This makes it possible to estimate the position of the wireless communication device even when there is an obstacle in the wireless section.

Although the first embodiment of the present invention has been described above, the present invention is not limited to the first embodiment described above, and various modifications and applications are possible without departing from the gist of the present invention. be. For example, in Embodiment ₁ , the case where the wireless communication devices 3 ₁ to 3 _n transmit the sensor information acquired by the sensor 36 to the base station 2 has been described. ˜3 _n may transmit data other than sensor information to the base station 2 .

1 gateway device, 2 base station, 3 ₁ to 3 _n wireless communication device, 11 CPU, 12 RAM, 13 flash memory, 14 maintenance communication unit, 15 external output communication unit, 16 GW side wired communication unit, 21 CPU, 22 RAM, 23 flash memory, 24 first wireless communication unit, 25 external output communication unit, 26 base station side wired communication unit, 31 CPU, 32 RAM, 33 flash memory, 34 second wireless communication unit, 35 for external output communication unit 36 sensor 37 switch 100 communication system 211 list collection unit 212 determination unit 213 parameter setting unit 214 transmission/reception processing unit 311 switch setting acquisition unit 312 switch number determination unit 313 information acquisition unit 314 address setting unit 315 transmission/reception processing unit;

Claims (4)

A method comprising a base station and a plurality of wireless communication devices, wherein at least one of the plurality of wireless communication devices relays and transfers signals, and transmits and receives data between the base station and the wireless communication devices A communication system for performing
The wireless communication device
one or more fixedly arranged first wireless communication devices;
and one or more second wireless communication devices located on the mobile body,
The base station
Based on the position information of the first wireless communication device closest to the predetermined second wireless communication device among the one or more first wireless communication devices, the position of the predetermined second wireless communication device is determined. Communication system to estimate. The second wireless communication device,
Acquiring radio wave intensity information indicating radio wave intensity from the first wireless communication device in the vicinity,
transmitting the acquired radio field intensity information to the base station;
The base station
The communication system according to claim 1, wherein the location information of the first wireless communication device closest to the second wireless communication device is acquired based on the radio field intensity information received from the second wireless communication device. The wireless communication device
having a switch with multiple states set;
3. The communication system according to claim 1, wherein one of said first wireless communication device and said second wireless communication device is set based on the state of said switch. a base station; and a plurality of wireless communication devices including one or more first wireless communication devices arranged in a fixed manner and one or more second wireless communication devices arranged in a mobile body; A position estimation method for a communication system in which at least one of the wireless communication devices relays signals and transmits and receives data between the base station and the wireless communication device,
Based on the position information of the first wireless communication device closest to the predetermined second wireless communication device among the one or more first wireless communication devices, the position of the predetermined second wireless communication device is determined. The location estimation method to estimate.

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