JP2013090135A - Position discrimination system and communication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a position discrimination system and a communication method, capable of reducing the exchange of communication route information between relay devices, with improved position discrimination accuracy by specified low power radio.SOLUTION: A position discrimination system 1 includes a plurality of relay devices 10 (relay devices 10-1, 10-2, 10-3) installed on a ceiling or a wall of a building, a position discrimination unit 12 and a small-sized transmitter 11. Because the transmitter is of a pendant type, the transmitter 11 can be carried at all times by wearing, and by the depression of a switch by a person in case of an emergency, the transmitter 11 transmits a radio wave including ID information. A certain number of relay devices 10 located in a mesh shape receive the radio wave, and the relay device receiving the radio wave transfers the ID information and a reception electric field intensity to the position discrimination unit 12. By this, the position discrimination unit 12 discriminates the occurrence of an emergency state and the location of the transmitter 11.

Description

  The present invention relates to a position determination system and a communication method for estimating the position of a moving transmitter, and more particularly to a position determination system and a communication method using specific low-power radio.

  2. Description of the Related Art Conventionally, a position determination system that transmits a predetermined radio wave from a moving transmitter and estimates the position of the transmitter with high accuracy by a plurality of receivers that receive the radio wave is known. In Patent Document 1, a unique marker number is transmitted on a radio wave from a transmitter, received by three or more transmitters and receivers installed at known positions, and received field strength is measured. A position discrimination system that estimates the position of a transmitter using number data is disclosed.

  In the position determination system of Patent Document 1, each transmitter / receiver predetermined in a wireless area receives radio waves from a transmitter, and the distance from each transmitter / receiver to the transmitter is determined based on the relationship between received electric field strength and distance. It is estimated by correcting the formula. When trying to estimate the position of the transmitter with such a combination of the transmitter and the receiver, the position estimation accuracy is proportional to the communication distance and becomes equal to or larger than the communication area size. Therefore, in order to increase the position accuracy, it is necessary to lower the transmission output of the transmitter or lower the sensitivity of the receiver, narrow the area for the receiver, and arrange many receivers.

  Therefore, the present applicant has disclosed a wireless communication system as shown in Patent Document 2. In Patent Document 2, a wireless communication system that communicates via a plurality of relay stations can be constructed by using a specific low power radio to narrow a wireless communication zone. By connecting a large number of nodes, the position estimation accuracy is improved, and a plurality of child nodes serving as relay stations can be connected to ensure communication reliability with a simple protocol.

JP 2002-236166 A JP 2009-4975 A

  As shown in Patent Document 1, the radio waves transmitted by the transmitter are collected by using three or more transmitters / receivers, and the identification number and the received electric field strength are collected. The distance is calculated by the Friis equation based on the relationship between the distance and the received electric field strength. When obtaining, the position of the transmitter can be accurately estimated by using the wireless communication system disclosed in Patent Document 2.

  However, in a system that communicates with a simple protocol as in Patent Document 2, it is necessary to arrange a repeater so that wireless zones overlap in order to eliminate a wireless dead zone. There may be a case where a radio collision occurs when the machine receives the signal and a plurality of repeaters simultaneously transmit the identification number and the received electric field strength. In this case, when the label number from the repeater with the first strongest received electric field strength and the received electric field strength disappear, the location from the repeater with the next strongest received electric field strength is recognized as the position of the transmitter. As a result, the position determination is wrong. In addition, when relaying by a plurality of relays is necessary, the exchange of communication path information between the relays increases.

  In order to improve the accuracy of position determination, how to avoid wireless collision and prevent the loss of information and reduce the exchange of communication path information between repeaters has been an issue. SUMMARY OF THE INVENTION An object of the present invention is to provide a position determination system and a communication method capable of improving the position determination accuracy by specific low power radio and reducing the exchange of communication path information between repeaters.

  In order to achieve the above-described object, a position determination system according to the present invention includes a portable transmitter that transmits a radio wave including its own ID information, and a transmitter that receives the radio wave transmitted by the transmitter. ID information and received electric field strength are acquired, and the received electric field strength is transmitted to a unit that displays the position of the transmitter together with the ID information, or transmitted through another relay device, and at least one relay A position display unit that collects ID information transmitted from the transmitter and the received electric field strength and displays the location of the repeater having the maximum reception sensitivity as the position of the transmitter. A repeater exceeding the threshold is characterized by starting transmission before other repeaters.

  In the position determination system according to the present invention, the repeater is characterized in that the transmission time is adjusted by a random delay.

  Further, in the position determination system according to the present invention, the transmitter, the relay unit, and the position determination unit use the same frequency, prevent transmission of information by adjusting the transmission time, and relay destinations of a plurality of relay units It is characterized in that information is stored in a repeater and communicated by relaying multihop.

  In the communication method of the position determination system according to the present invention, the portable transmitter transmits a radio wave including ID information, the relay receives the radio wave transmitted by the transmitter, and transmits the received electric field strength together with the ID information to the transmitter. The position display unit collects the relay process to be transmitted to the position display unit for displaying the position of the position, or the relay process to be transmitted through another relay unit, the ID information and the received electric field strength transmitted from at least one relay unit, A position display step of displaying the location of the repeater where the highest received electric field strength is obtained as the position of the transmitter, and the repeater step includes a repeater having a received electric field strength exceeding a threshold value and other relays. The transmission is started before the machine.

  In the communication method of the position determination system according to the present invention, the relay process is characterized in that the transmission time is adjusted by a random delay.

  Moreover, in the communication method of the position determination system according to the present invention, in the relay process, the transmitter, the relay, and the position determination unit use the same frequency, and the collision of information is prevented by adjusting the transmission time, and The relay destination information of a plurality of relay devices is stored in the relay device, and communication is performed by relaying multihop.

  By using the position determination system and the communication method according to the present invention, there is an effect of improving the accuracy of position determination by specific low-power radio. Also, there is an effect of suppressing the exchange of communication route information between relay devices by constructing route information centered on the relay device and registering and fixing the route information in the relay device.

It is an outline figure showing the whole outline of a position discriminating system concerning an embodiment of the present invention. It is a block diagram which shows the structure of the position discrimination system which concerns on embodiment of this invention. It is explanatory drawing explaining the communication timing in the position discrimination system which concerns on this embodiment. It is explanatory drawing explaining the format structure of the radio | wireless packet shown in FIG. It is explanatory drawing explaining the wireless network which concerns on this embodiment. It is explanatory drawing explaining an example of the relay path | route of the position determination system which concerns on this embodiment. It is a flowchart figure which shows the main routine process of the position determination system which concerns on this embodiment. It is a flowchart figure which shows the processing flow of the relay machine which concerns on this embodiment. It is the time chart figure which showed the process of the relay machine by the flow of the process of FIG. It is explanatory drawing explaining the relay route information (routing information) memorize | stored in the memory of the relay machine which concerns on this embodiment. It is explanatory drawing explaining the radio | wireless zone of the position determination system which concerns on other embodiment. It is explanatory drawing explaining the example of a display of the position determination unit which concerns on this embodiment.

  Hereinafter, the best mode for carrying out the present invention (hereinafter referred to as an embodiment) will be described with reference to the drawings.

  FIG. 1 shows an overall outline of the position determination system 1. The position determination system 1 includes a plurality of relay units 10 (relay units 10-1, 10-2, 10-3) installed on a ceiling or a wall in a building, a position determination unit 12, and a small size. And a transmitter 11. Since the transmitter is a pendant type, the transmitter 11 can be worn with the transmitter 11 at all times, and when a person pushes down the switch in an emergency, the transmitter 11 transmits radio waves including ID information. Several relay devices 10 arranged in a mesh form receive the radio wave, and the received relay device 10 transfers the ID information and the received electric field strength to the position determination unit 12 so that the position determination unit 12 is in an emergency situation. And the location of the transmitter 11 is discriminated.

  Here, the transmitter 11, the repeater 10, and the position determination unit 12 have established communication by specific low-power radio, and a position determination system is formed by arranging repeaters at intervals of several tens of meters to form a wireless network. It is possible to build By using this position determination system as an emergency call system such as a hospital or a care facility, it is possible to determine the emergency call and whereabouts.

  FIG. 2 shows the configuration of the position determination system 1 and shows the structure of the transmitter 11, the plurality of relays 10, and the position determination unit 12. One of the characteristic features of the present embodiment is that, in order to reduce the size and weight of the transmitter 11 and prolong the battery life, the transmitter 11 specializes only in the transmission function, and transmits radio waves after the transmission start switch 13 is pushed down as much as possible. The time is short (for example, several seconds). The transmitter 11 transmits the ID information and the transmission unit 15 to the relay unit or the position determination unit, the antenna 16 connected to the transmission unit 15, the transmission start switch 13, and the transmission start switch 13 when pressed. And a control unit 14 that transmits ID information.

  The repeater 10 includes a receiving unit 17 that receives ID information from the transmitter 11, a transmitting unit 18 that transmits ID information and the like to the position determination unit 12, and an antenna 21 connected to the receiving unit 17 and the transmitting unit 18. A control unit 19 for calculating reception signal strength indication (RSSI) of radio waves received from the transmitter 11 and controlling transmission / reception of ID information, and a memory 28 for storing relay information and the like. Yes. When receiving the radio wave including the ID information from the transmitter 11, the relay device 10 transmits the ID information and the received electric field strength to the position determination unit 12. The repeater 10 is mounted in the vicinity of the lamp on the ceiling or wall of the building, and is arranged in a mesh shape at intervals of several tens of meters. A plurality of repeaters 10 can be relayed and transmitted to the position determination unit 12. It is.

  The position determination unit 12 includes a receiving unit 25 that receives ID information and received electric field strength (RSSI) from the repeater 10, a transmitting unit 26 that transmits information to the repeater 10 and the position determining unit 12, a receiving unit 25, Controls the antenna 27 connected to the transmission unit 26, the operation / display unit 22 that displays relay information, position names, etc. for the repeater 10 and displays the determined position, and the reception / operation / display unit 22 of ID information. It has the control part 23 and the memory 24 which memorize | stores relay information etc. The position discriminating unit 12 communicates with a plurality of repeaters 10 and displays the position of the repeater 10 that has received a radio wave having a high received electric field strength on the operation / display unit 22 as the position of the transmitter 11. In addition, the position determination unit 12 realizes a multi-hop wireless network by determining an optimum relay destination described later and storing it in each relay station. Here, the wireless network based on multi-hop is not only that terminals such as the transmitter 11, one repeater 10 and the position determination unit 12 communicate directly but also via other terminals (relay 10). It is a wireless network that enables communication with a wider range of terminals (relay device 10).

  FIG. 3 shows communication timings in the position determination system, with the reception side on the upper side and the transmission / reception timing on the transmission side on the lower side. In the present embodiment, in order to reduce the power consumption in the reception process, for example, the reception operation is executed for several tens of ms at an interval of N = 500 ms, and then the sleep state is set. Also, in the transmission process, the preamble is repeatedly transmitted for Nmsec or more before the actual message is transmitted, so that the actual message can be received by transmitting the actual message after the preamble even in intermittent reception.

  FIG. 4 shows a format configuration of the wireless packet shown in FIG. The radio packet transmitted by the transmission side includes a preamble and an actual message. In the preamble, the transmission side repeatedly transmits bit synchronization, frame synchronization, system ID, transmission ID, and error check CRC. After that, the transmitting side sets the bit synchronization, frame synchronization, system ID, transmission source ID, message type, data length, data, CRC, etc. that become the actual message at the timing when the reception side is ready to receive the repetition information of the preamble by intermittent reception. Send. Here, from the bit synchronization to the transmission source ID is the same as the preamble, but the message type, data length, data, etc. after the transmission destination ID are different from the preamble. The message type includes a status collection message for collecting the communication status of each repeater and a route construction message for transmitting the relay information to be relayed to each relay station for the purpose of building route information. The data length indicates the length of the subsequent data, and it is possible to store route information necessary for creating a routing table, received electric field strength, and the like in the data.

  FIG. 5 shows a wireless network of the position determination system, and shows devices constituting the wireless network and their wireless arrival zones. In FIG. 5, one transmitter 11, four relay devices (relay devices 10-1 to 10-4), and one position determination unit 12 are arranged, and the relay device 10-1 and the relay device are relayed. Since the radio arrival zones with the machine 10-2 intersect, the relay machine 10-1 and the relay machine 10-2 can communicate with each other. Similarly, repeater 10-1 and repeater 10-3, repeater 10-2 and repeater 10-4, repeater 10-4 and repeater 10-3, repeater 10-3 and position determination unit 12 Communication is possible. In FIG. 5, the transmitter 11 is located between the repeater 10-1 and the repeater 10-2, and radio waves from the transmitter 11 are received by the repeater 10-1 and the repeater 10-2. The data is transmitted to the position determination unit 12 through two relay routes. The first relay path is the transmitter 11, the relay machine 10-1, the relay machine 10-3, and the position determination unit 12, and the second relay path is the transmitter 11, the relay machine 10-2, and the relay machine 10. -4, the repeater 10-3 and the position determination unit 12.

  FIG. 6 shows an example of the relay route of the position determination system. For convenience of explanation, the communication direction using the wireless arrival zone of the transmitter 11 is indicated by an arrow, and the wireless arrival zone is omitted. When the transmission start switch of the transmitter 11 is first depressed, a radio wave including ID information is transmitted from the transmitter 11 (ID1). The radio wave (wireless packet) transmitted from the transmitter 11 is received by the relay device 10-1 (ID2), the relay device 10-2 (ID3), and the relay device 10-3 (ID4). Next, the flow of processing of the position determination system in the present embodiment under the above-described situation will be described with reference to FIGS.

  FIG. 7 shows a main routine process of the position determination system. The main routine process is executed in association with a plurality of repeaters, position determination units, and transmitters. The relay route confirmation in step S10 is to confirm the relay route between a plurality of repeaters and the position determination unit, and the location of each repeater, the ID information, and the relay route when the repeater is installed are actually It confirms whether it corresponds with the position determination system. If the relay routes are different, the position determination unit executes processing such as storing the new relay route in the corresponding relay device by setting the relay route in step S12. Details of the processing contents of the relay route setting will be described later.

  After the relay path by the position determination unit is correctly set, the relay and the position determination unit execute the position determination process by repeating the transmitter position determination in step S14 and step S16 which is a loop process. In this process, the relay device receives the wireless packet transmitted from the transmitter, and transmits the received electric field strength of the wireless packet and the ID information of the transmitter to the position determination unit in a wireless packet. The position determination unit determines the position of the repeater that shows the strongest received electric field strength as the position of the transmitter based on the received electric field strength received by at least one repeater and the ID information of the transmitter. When similar wireless packets are received from a plurality of relays, the expected position may be displayed assuming that there is a transmitter in the middle of the plurality of relays.

  FIG. 8 shows the processing flow of the repeater, and FIG. 9 is a time chart showing the processing of the repeater according to the processing flow of FIG. 6, where the horizontal axis shows the elapsed time, and the vertical axis shows the transmitter and each repeater. The transmission / reception timing for every 10 ms slot is shown. Hereinafter, the flow of processing will be described with reference to FIGS. 8 and 9 based on an example of the relay route of the position determination system shown in FIG. In FIG. 8, when the repeater starts processing, first, a signal such as a wireless packet transmitted from the transmitter by intermittent reception is monitored. Next, as shown in FIG. 9, when the transmitter switch is pressed, the transmitter (ID1) transmits a wireless packet including ID1, and in step S20, the relay device 10-1 (ID2) and the relay device 10 are transmitted. -2 (ID3) and repeater 10-3 (ID4) receive the wireless packet.

  In step S22, each repeater decodes the ID information of the transmission source from the received wireless packet, extracts the ID information, and determines in step S23 whether the ID information (ID1) of the transmitter is present. If it is determined in step S23 that the ID information is not from the transmitter, the process returns to step S20. If it is determined in step S24 that the ID information is from the transmitter, the relay route is confirmed in step S24, and the relay route and the number of relays are read from the memory. Next, a predetermined slot allocation is confirmed in order to secure a slot for preferentially transmitting a radio packet having a large received electric field strength. Here, slots to be preferentially transmitted are 0 to 5 (first half slot), and slots to be normally transmitted are 6 to 9 (second half slot). Details of the slot allocation confirmation will be described later.

  Here, as shown in FIG. 6, in the repeater 10-1 (ID 2) and the repeater 10-2 (ID 3), the ID information that is the radio wave from the transmitter 11 is “ID 1”, and the received electric field strength is Radio waves that are above a certain value (RSSI large) are received. Further, the repeater 10-3 (ID4) receives radio waves whose ID information is “ID1” and is less than a certain value (RSSI is small). The repeater 10-4 (ID5) is out of service area and cannot receive radio waves from the transmitter 11 (ID1). For this reason, the wireless packet from the transmitter 11 is received by the three relay devices and transferred to the position determination unit 12 through the three relay routes.

  In step S26 to step S30 in FIG. 8, each repeater generates a random number from 0 to 5 in order to apply a random delay in the first half slot when the received electric field strength is a certain value or more (step S28). If is less than a certain value, a random delay is applied in the second half slot, so random numbers 6 to 9 are generated (step S30). By applying such a random delay, it is possible to shift the transmission timing from each repeater.

  In step S32, each relay station calculates a waiting time until transmission of ID information is started. Specifically, when the received electric field strength is equal to or greater than a certain value exceeding the threshold: ID information transmission start waiting time = waiting time (ms) = 10 ms * (random number of 0 to 5) (Equation 1), received electric field strength Is less than a certain value below the threshold: ID information transmission conversion waiting time = waiting time (ms) = 10 ms * (random number of 6 to 9)... Then, the process proceeds to step S34. Note that the possible values of the random numbers 0 to 5 in Expression 1 and 6 to 9 in Expression 2 are limited depending on the number of relay routes, for example, 0 to 3 in Expression 1 and 6 to 7 in Expression 2. Is done.

  By such processing, the repeater whose received electric field strength exceeds the threshold value can start transmission earlier than other repeaters, and the transmission signal collision at the same timing, which has been a problem in the past, has been caused. Can be prevented. In addition, when a plurality of relays are required, each repeater confirms a subsequent transmission destination based on the above-described slot allocation confirmation in step S34 and prepares for transfer with random delay.

  FIG. 10 shows relay route information (routing information) stored in the memory of the repeater used for slot allocation confirmation. The relay route information is set in each relay by the position determination unit in steps S10 and S12 of FIG. For example, the relay route information of the relay machine 10-1 (ID2) in FIG. 10 can be transmitted to the position determination unit with the number of times of relaying twice when relaying the relay machine 10-2 (ID3) indicated as "identification code". Yes, it is shown that if the relay device 10-3 (ID4) is relayed, it can be transmitted to the position determination unit with one relay count. Further, “Reception level” in FIG. 10 indicates the reception level of the reception electric field strength in the repeater, and “Decision” in FIG. 10 indicates that the repeater 10-3 (ID4) having a small number of relays is determined by the initial setting. Indicates that it is a relay destination. From this relay route information, each relay station can know the transmission destination in the subsequent stage.

  In step S36 of FIG. 8, based on the calculated waiting time, each repeater transmits the received electric field strength together with the ID information. Here, as shown in the first cycle of FIG. 9A, the repeater 10-1 (ID2) has a large received electric field strength (RSSI). ID1) and the received electric field strength (RSSI large) are transmitted, and the radio packet is received by the repeater 10-3 (ID4). Next, as shown in the second cycle of (B) in FIG. 9, the repeater 10-2 (ID3) similarly receives the ID information (ID1) and the received electric field strength (large RSSI) with a delay of 20 ms based on Equation 1. The wireless packet is received by the repeater 10-4 (ID5).

  As shown in the third cycle of FIG. 9C, the repeater 10-3 (ID4) transmits ID information (ID1) and received electric field strength (high RSSI) by opening one slot based on the relay route information. The wireless packet is received by the position determination unit (ID0). Next, as shown in the fourth cycle of (D) in FIG. 9, the repeater 10-4 (ID5) uses the wireless packet received from the repeater 10-2 (ID3) in the second cycle based on the relay route information. One slot is opened to transmit ID information (ID1) and reception field strength (RSSI high), and the wireless packet is received by the repeater 10-3 (ID4). Next, the repeater 10-3 (ID4) transmits ID information (ID1) and received electric field strength (RSSI large) in the next slot, and the wireless packet is received by the position determination unit (ID0).

  Since repeater 10-3 (ID4) has a small received electric field strength (RSSI), ID information (ID1) and received electric field strength (RSSI) are transmitted with a delay of 70 ms based on Equation 2, and the radio packet is located Received by the discrimination unit (ID0). Since the repeater has a transmitter and a receiver, it is possible to perform transmission and reception separately by avoiding transmission / reception in the same slot as described above.

  By the processing of the repeater described above, the position determination unit (ID0) is configured so that the repeater 10-1 (ID2), the repeater 10-2 (ID3), and the repeater are in descending order of the RSSI from the repeater located in the vicinity of the transmitter. The wireless packet of 10-3 (ID4) is received, and the position corresponding to the repeater 10-1 (ID2) having the maximum received electric field strength is displayed as the position of the transmitter.

  FIG. 11 shows a wireless zone of the position determination system 2 according to another embodiment. In this embodiment, a wide wireless zone is formed by nine repeaters (10-1 to 10-9), and the repeaters (10-1 to 10-4) are equidistant from the transmitter 11. This is an example in which the transmitter 11 is moved. Depending on the movement position of the transmitter 11, up to four repeaters 10 may exhibit a large received electric field strength, and the number of relays may be up to three depending on the relay route information. In such a case, the number of slots shown in FIG. 9 is increased, and the repeater 10 whose received electric field strength exceeds the threshold value can start transmission before the other repeaters 10. Further, as the number of repeaters 10 increases, not only the repeater 10 that exhibits the maximum RSSI is determined as the position of the transmitter 11, but also the position of the transmitter 11 is determined by combining the received electric field strength (RSSI) of a certain value or more. It is also suitable to do.

  FIG. 12 is a display example of the position determination unit. The operation / display unit 22 displays a floor plan in the building where the repeater is placed, and the repeater is displayed at a position corresponding to the place where the repeater is placed. In this embodiment, there are two types of position display modes. When the transmitter switch is pressed in the first display mode, as shown in FIG. , And the pressed time. In the second display mode, when the switch of the transmitter is pressed, an intermediate point proportional to the received electric field strength of the plurality of relays is displayed as the position of the transmitter, and reception from a plurality of relays is indicated. Display as a text message.

  As described above, by using the position determination system and the communication method according to the present embodiment, the position determination can be performed by combining the received electric field strength measured by the repeater and the short-range communication using the specific low power radio. Accuracy can be improved. As the specific low power radio, in addition to the conventional low power communication system, a second generation low power data communication system (ARIB STD-T66) may be preferably used. In addition, by constructing route information centered on the repeater and registering and fixing the route information in the relevant repeater, the exchange of communication route information between repeaters is suppressed, so that relaying is possible. The communication traffic in can be reduced.

  In this embodiment, the relay route information of the relay device is managed using the position determination unit, but the present invention is not limited to this, and a server or a management unit for managing the relay route information of the relay device is separately provided, A position determination system in which a plurality of position determination units may receive the ID information and the received electric field strength from the server or the management unit, collectively determine the position determination of the transmitter, and transmit the result to the position determination unit However, it is preferable.

  1, 2 Position determination system, 10 Repeater, 11 Transmitter, 12 Position determination unit, 13 Transmission start switch, 15, 18, 26 Transmitter, 16, 21 Antenna, 17, 25 Receiver, 14, 19, 23 Control Part, 22 operation / display part, 24, 28 memory.

Claims (6)

A portable transmitter that transmits radio waves including its own ID information;
Receives the radio wave transmitted by the transmitter, acquires the transmitter ID information and the received electric field strength, and transmits the received electric field strength together with the ID information to the unit that displays the position of the transmitter, or via another relay device A plurality of repeaters that transmit
A position display unit that collects ID information and received electric field strength transmitted from at least one repeater, and displays the placement location of the repeater with the maximum reception sensitivity as the position of the transmitter;
Have
A position determination system characterized in that a repeater whose received electric field strength exceeds a threshold starts transmission before other repeaters. The position determination system according to claim 1,
The position determination system characterized in that the transmission time of the repeater is adjusted by random delay. The position determination system according to claim 1 or 2,
The transmitter, repeater, and position determination unit use the same frequency to prevent transmission of information by adjusting the transmission time, and store relay destination information of multiple repeaters in the repeater, allowing relaying A position determination system characterized by multi-hop communication. The portable transmitter transmits a radio wave including ID information, and the relay receives the radio wave transmitted by the transmitter and transmits the received electric field strength together with the ID information to a position display unit that displays the position of the transmitter, or A relay process for transmitting via another relay machine;
A position display step in which a position display unit collects ID information and received electric field intensity transmitted from at least one repeater, and displays the position of the repeater at which the highest received electric field intensity is obtained as the position of the transmitter; ,
Including
In the relaying step, the relay method in which the received electric field strength exceeds a threshold value starts transmission before the other relay devices. In the communication method of the position determination system according to claim 4,
The communication method of the position determination system, wherein the relay process adjusts the transmission time by a random delay. In the communication method of the position determination system according to claim 4 or 5,
In the relay process, the same frequency is used for the transmitter, the relay device, and the position determination unit, the transmission timing is adjusted to prevent information collision, and the relay destination information of multiple relay devices is stored in the relay device. A communication method of a position determination system, characterized by performing multihop communication that can be relayed freely.

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