JP2007155523A - Position detection method, and position detection system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of performing accurate position detection even in a situation where only reflected wave can be received between a node and a base station, in a position detection method for detecting a node position of a radio communication system by the principle of trilateration by measuring the distance between the node and a surrounding base station. <P>SOLUTION: The base station determines whether an observed signal transmitted from the node is direct wave or reflected wave based on identification information of the synchronizing signal, and a server corrects the distance between the node and base station using the determination results of the direct wave or reflected wave. Thus, the distance between the node and base station can be accurately measured even in an environment where only reflected wave can be caught. Even when the prospect is not secured between the base station and node, the position detection of high accuracy is achievable. <P>COPYRIGHT: (C)2007,JPO&amp;INPIT

Description

  The present invention relates to a radio communication system including a large number of nodes and a position detection method for the nodes. In particular, in the surrounding base stations of the node whose position is to be detected, it is determined whether the arrival path of the signal used for obtaining information on the distance between the node and the base station is a direct wave or a reflected wave, and the node is used by using the determined result. The present invention relates to a position detection method, a position detection system, a base station apparatus, and a server apparatus.

  Conventional position detection methods include the method of triangulation using the received signal strength (RSS) and the distance from the relationship with the attenuation of the received signal strength, Triangular survey using distance measurement using distance of arrival (ToA: Time of Arrival) or time difference of arrival (TDoA), triangulation using radio arrival angle (AoA: Angle of Arrival) A method for identifying a position by collation with a generated received signal strength map is known.

  In the outdoors, GPS (Global Positioning System) based on TDoA using radio waves from satellites has become widespread. In addition, a three-side survey system using TDoA, a map matching system using RSS, and a three-side survey system using ultrasonic ToA using radio waves of a wireless LAN (Local Area Network) have been put into practical use. (For example, refer to Patent Document 1 and Non-Patent Document 1.)

In the above-mentioned position detection system, especially in ToA and TDoA, when the signal arrival path between nodes that measure the distance does not reach the direct wave but only the reflected wave from the wall or the like, the path length of the reflected wave is the direct wave. If the length is longer, an error occurs and the position detection accuracy deteriorates. On the other hand, in Patent Document 1, it is determined whether the antenna receives a reflected wave due to multipath based on position data and map data, and time data based on the reflected wave due to multipath is not selected. Thus, it is disclosed that an error based on a reflected wave due to multipath is reduced.
JP 2004-101254 A A. Savvides, CC Han, MB Srivastava, "Dynamic Fine-Grained Localization in Ad-Hoc Wireless Sensor Networks", in the proceedings of the International Conference on Mobile Computing and Networking (MobiCom) 2001, Rome, Italy, July 2001 JP 2004-163195 A

  In the position detection system described above, there is a problem that the position detection accuracy deteriorates due to a multipath reflected wave except for a map matching system using RSS. For this reason, it is necessary to install a base station so as to ensure a line of sight as much as possible between the position detection target node and the surrounding base stations, thereby reducing the influence of multipath. For this reason, there exists a subject that the cost concerning base station installation becomes high. In Patent Document 2, it is described that data having no multipath is selected. However, the position cannot be detected in an environment where there are many multipaths.

  In addition, in the map matching system using RSS, it is necessary to create an RSS database when the base station is installed. In addition, there is a problem in that the position detection accuracy deteriorates due to a difference between the RSS database examined in advance and the RSS measurement data due to the influence of the change in the layout of the base station and the movement of the person / obstacle.

  The present invention has been made in view of the above, and in a wireless communication system, a signal used for measuring the distance between a position detection target node and a surrounding base station has directly arrived or is reflected by a ceiling, a wall, or the like. A wireless system that can determine the node position using the determined result, a server, a base station, a node constituting the system, and a node position detection method in the system For the purpose. Here, the node indicates a terminal used by a user or a sensor node equipped with a sensor for sensing a real environment.

In order to solve the above problems and achieve the object, in the wireless communication system according to the present invention, a position detection target node, base stations around the node, and a ceiling on a signal arrival path between the node and the base station. A system composed of reflectors such as walls and walls, and a server that calculates the node position,
There are two types of signals: a synchronization signal for time synchronization to measure the distance to surrounding nodes or base stations, and an observation signal to measure the distance for ToA or the reception time for TDoA A means for transmitting / receiving a signal, a means for measuring the distance to the reflector using the synchronization signal and the observation signal, a means for measuring the reception amplitude of the observation signal, and information on the obtained reception amplitude. Means for controlling the transmission output of the observation signal, and means for multiplexing the identification information necessary for determining whether the observation signal is reflected by a reflector or reaches directly to the synchronization signal. At least one node,
Two types of signals: a synchronization signal for time synchronization to measure the distance between the base station and the node, and an observation signal to measure the distance for ToA or the reception time for TDoA Transmitting / receiving means, means for measuring the distance to the reflector using the synchronization signal and the observation signal, and the observation signal using the identification information of the synchronization signal transmitted from the node A base station comprising means for determining whether it has arrived reflected or has arrived directly, and means for communicating with a server for calculating the position of the node;
The means for communicating with the base station, the base station or information on the distance between the base station and the node collected by the node, the information on the difference in signal arrival time between the synchronization signal and the observation signal, and the observation signal reflected by the reflector. A measurement database having information indicating whether it has arrived or received directly, a base station location database storing location information of the base station, and information on the time or time difference between the node and the base station using the measurement database information A system comprising a server having means for correcting the position of the node based on the principle of triangulation from the corrected information and the information in the base station position database,
At the base station, it is determined whether the observation signal transmitted from the node has arrived directly on the route to the base station or reflected by a reflector such as a ceiling or wall,
The server provides a position detection method that improves position detection accuracy by correcting the distance information between each node and the base station or the signal arrival time difference of the observation signal using the discrimination result in the base station. To do.

  According to the present invention, even in a situation where a line of sight cannot be secured between a node and a base station, it is determined whether a signal for measuring the distance between the node and the base station has arrived as a direct wave or a reflected wave. When it arrives, the position detection accuracy of the node can be improved by correcting the distance information between the node and the base station.

  In particular, in a system that handles a large number of nodes and a large number of base stations, there is a problem that a base station is installed at a high place in order to secure a view between the base station and the node, and the installation cost becomes high. According to the present invention, it is not necessary to secure a line of sight between the base station and the node, and the installation cost can be kept low.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows a configuration of a wireless communication system according to the present invention and a system configuration diagram for detecting the position of a node. The position detection target node 103 periodically transmits an observation signal and a synchronization signal at the same time, in order to measure information regarding the distance to the surrounding base stations 102a, 102b, and 103c. The base stations 102a, 102b, and 102c measure the signal arrival time difference between the synchronization signal and the observation signal, and notify the server 101 of the measurement result. The server 101 calculates the position of the node 103 from the known coordinates of the surrounding base stations 102a, 102b, and 103c and the information about the distance between the node 103 and the surrounding base stations 102a, 102b, and 103c by the principle of triangulation.

  Here, the synchronization signal may be an electromagnetic wave that propagates at the speed of light, and the observation signal may be an ultrasonic wave that propagates at the speed of sound. As a result, the propagation time of the synchronization signal is sufficiently shorter than the propagation time required for the observation signal to be transmitted from the node and received by the base station, so that the reception time of the synchronization signal is set to the synchronization signal (and the observation signal). The transmission time of the observation signal can be obtained with sufficient accuracy.

  If the base stations 102a, 102b, and 102c are installed in a high place near the ceiling 105, the line of sight between the node 103 and the base stations 102a, 102b, and 102c can be secured, so the node 103 and the base stations 102a, 102b, and 102c Information about the distance between 102c can be measured correctly.

  FIG. 2 is an explanatory diagram regarding the influence of reflected waves in the wireless communication system according to the present invention. When there is an obstacle 201 between the base station 102a and the node 103, the observation signal transmitted by the node 103 may not reach the base station 102a as a direct wave but may arrive as a reflected wave on the ceiling 105.

  In particular, if the base stations 102a, 102b, and 102c are installed at a location lower than the ceiling, the influence of an obstacle that blocks the observation signal transmitted by the node 103 that is the position detection target is increased.

  At this time, since the path of the reflected wave is longer than the path that reaches as a direct wave, there is a problem that information regarding the distance between the node 103 and the base station 102a is largely erroneous and the position detection accuracy of the node 103 is deteriorated.

  Comparing FIG. 1 and FIG. 2, the base station installation cost is lower in FIG. 2 because it is not necessary to install the base stations 102a, 102b, and 103c near the ceiling 105.

  FIG. 3 shows a comparison diagram regarding the measurement distance of the direct wave and the reflected wave in the wireless communication system according to the present invention. When the distance between the base station and the obstacle is fixed at 50 cm, the distance between the base station and the ceiling is fixed at 200 cm, the distance between the node and the ceiling is fixed at 200 cm, and the distance between the node and the obstacle is changed The measured distance between stations is shown.

  Conventionally, a method that does not use the information obtained from the reflected wave is used, but in the present invention, the distance when the direct wave arrives from the reflected wave information is estimated by distinguishing the direct wave from the reflected wave. By doing so, we will actively utilize the information obtained from the reflected waves.

  FIG. 4 shows an explanatory diagram of a method for estimating the distance between the node and the base station from the distance measured by the reflected wave in the embodiment of the present invention.

  First, assuming that the distance between the base station 102a and the ceiling 105 is a, the distance between the node 103 and the ceiling 105 is b, and the measurement distance by the reflected wave is d, the node-base station distance d ′ is expressed by the following formula: 1 can be represented.

  However, when measuring a distance larger than twice the distance b from the node 103 to the ceiling 105, the embodiment of the present invention cannot distinguish between a reflected wave and a direct wave for the reason described later in FIG. The measurement distance d is directly used as the node-base station distance d ′.

  FIG. 5 shows an explanatory diagram of a procedure for obtaining a node position in the embodiment of the present invention. First, the distance a between the base station 102a and the ceiling 105 is measured (Step 1). Here, the ceiling 105 will be described as an example. As a distance measuring method, the base station 102a simultaneously transmits a synchronization signal and an observation signal. In order to identify the types of observation signals to be transmitted simultaneously, the synchronization signal has identification information called MODE as an element, and is transmitted as MODE = 0. When a surrounding node or base station receives a synchronization signal with MODE = 0, it does not transmit a synchronization signal or an observation signal for a certain time after reception.

  The base station 102a stores the timing at which the synchronization signal and the observation signal are transmitted, and calculates the distance from the time difference between the timing at which the observation signal reflected by the ceiling 105 is received by the base station 102a itself and the stored transmission timing.

  Next, the distance b from the node 103 to the ceiling is measured (Step 2). The distance is measured in the same manner as the base station 102a.

  Next, in the node 103, a transmission output P that does not pick up the reflected wave from the ceiling is obtained (Step 3). This specific method will be described later with reference to FIG.

  Next, the node 103 transmits an observation signal at a transmission output P or less (Step 4). At this time, the synchronization signal is transmitted as identification information MODE = 1 of the observation signal.

  When a surrounding node or base station receives an observation signal after receiving a synchronization signal with observation signal identification information MODE = 1, it is determined that the observation signal is received as a direct wave.

  Next, the node 101 transmits a synchronization signal with the observation signal identification information MODE = 2, and simultaneously transmits the observation signal with the maximum transmission output.

  The base station 102a that has received the synchronization signal of the observation signal identification information MODE = 2 calculates the distance d from the difference between the reception timing of the synchronization signal transmitted from the node 103 and the reception timing of the observation signal (Step 6).

  Next, the base station 102a determines whether the received observation signal is a direct wave or a reflected wave (Step 7). This specific method will be described later with reference to FIG.

  The base station 102a notifies the server 101 of the direct wave / reflected wave determination result, the distance a between the base station 102a and the ceiling 105, the distance b between the node 103 and the ceiling 105, and the distance d measured by the base station 102a. To do. However, in a system that performs position detection using a time difference of arrival (TDoA), arrival time information t is reported instead of the distance d information.

  The server 101 collects information from the base stations 102 a, 102 b, and 102 c around the node 103. When the base station 102a determines that the wave is a reflected wave, the distance between the node 103 and the base station 102a is corrected according to Equation 2 (Step 8). If the node 103 and the base stations 102b and 102c are direct waves, the measured distance is directly used for the position detection calculation for the direct waves.

  The server 101 obtains the position of the node 103 by performing position detection calculation using the corrected distance (Step 9).

  Step 4 to Step 9 are repeatedly executed N times, and the process returns to Step 1.

  FIG. 6 is an explanatory diagram relating to a method for determining a reflected wave in the embodiment of the present invention.

  In Step 4, the observation signal is transmitted with the transmission output P or less. At this time, the observation signal is received by the base station 102b and is not received by the base station 102a.

  In Step 5, the observation signal is transmitted at the maximum transmission output. At this time, it is assumed that the observation signal can be received by both the base station 102a and the base station 102b.

  At this time, the synchronization signal transmitted in Step 4 and Step 5 includes the ID of the identifier of the transmitting node, the identification information MODE of the observation signal used for the reflected wave determination, the transmission period Td of Step 4 and Step 5, and the nodes 103 and 105 to the ceiling 105. Has distance b as an element.

  The base station 102b can receive the observation signal both in Step 4 and Step 5. Therefore, both the identification information MODE = 1 and MODE = 2 of the observation signal come alternately. In addition, the observation signal reception interval is substantially close to the observation signal transmission timing interval Td of the node 103. In such a case, in the reflected wave determination in Step 7, it is determined that a direct wave has been received.

  On the other hand, even if the base station 102a receives the synchronization signal carrying the identification information MODE = 1 of the observation signal, the base station 102a cannot receive the observation signal and receives the observation signal only when the identification information MODE = 2 of the observation signal. . When the node 103 periodically transmits MODE = 1 and MODE = 2 alternately, the observation signal reception interval at the base station 102a is approximately twice the observation signal transmission interval of the node 103 and is close to 2Td. Become. In such a case, in the reflected wave determination in Step 7, it is determined that the reflected wave has been received.

  Here, when the observation signal is transmitted with the transmission output P or less, the distance reached by the observation signal identification information MODE = 1 is 2b or less. Therefore, when the distance between the node and the base station is larger than the distance 2b, a signal of MODE = 2 is always received. In this case, it is not possible to distinguish between a direct wave and a reflected wave. Therefore, considering this case, it is necessary to divide Equation 1 into the following Equation 2.

  FIG. 7 shows a configuration diagram of a node in the embodiment of the present invention. The node 103 includes an antenna 701 for transmitting and receiving a synchronization signal, a synchronization signal transmission unit 702 that performs encoding and modulation processing of the synchronization signal, a synchronization signal reception unit 703 that performs demodulation and decoding processing of the synchronization signal, and an observation signal The observation signal transmitting unit 705 for generating the observation signal, the transmission output control unit 706 for controlling the transmission output of the observation signal, the microphone 707 for receiving the observation signal, and the reception of the observation signal An observation signal receiving unit 708 for detecting, a reception amplitude measuring unit 709 for measuring the reception amplitude of the observation signal, a distance to the ceiling is calculated, a transmission output of the observation signal is determined, and a synchronization signal is multiplexed It comprises a control unit 710 that determines signal information, and a timer 711 that is necessary to measure the transmission / reception timings of synchronization signals and observation signals.

  Here, a sound wave or an ultrasonic wave is assumed as the observation signal, and the speaker 704 and the microphone 707 are used as the constituent elements. However, when the observation signal is wireless, the observation signal transmission unit 705 is the same as the synchronization signal transmission unit 702. The observation signal receiving unit 708 has the same configuration as the synchronization signal receiving unit 703. The transmission output control unit 706 and the reception amplitude 707 have the same functions even if the circuit configuration is different between the case where the observation signal is voice / ultrasonic and the case where the observation signal is wireless.

  FIG. 8 is an explanatory diagram illustrating a method for obtaining the transmission output P that does not pick up the reflected wave from the ceiling in the embodiment of the present invention.

  First, in Step 2 described with reference to FIG. 5, when the distance b from the node 103 to the ceiling 105 is measured, the observation signal transmission output is transmitted at the maximum. The observation signal reflected by the ceiling 105 is received, and the reception amplitude measuring unit 709 measures the reception amplitude. The minimum reception amplitude necessary for detecting the observation signal by the observation signal receiving unit 708 is set as a reception determination threshold value. The relationship between the transmission output and the reception amplitude is examined in advance, and the transmission output P in which the reception amplitude of the observation signal becomes the reception determination threshold is determined from the difference between the reception amplitude received when the transmission output is maximum and the reception determination threshold.

  In addition, it is confirmed that an observation signal is not received when transmission is performed with a p (dB) output lower than the transmission output P obtained here.

  Another embodiment for obtaining a transmission output P that does not pick up a reflected wave from the ceiling will be described. The observation signal is transmitted at the maximum transmission output, and it is confirmed that the reflected wave from the ceiling 105 is received. Next, the transmission output is lowered by p (dB) and transmitted to check whether the observation signal can be received. If the observation signal can be received, the transmission output is further reduced by p (dB) to check whether the observation signal can be received. In this way, the transmission output of the observation signal is continuously lowered until the observation signal cannot be received, and the transmission output P that does not pick up the reflected wave from the ceiling is obtained.

  FIG. 9 shows a configuration diagram of the base station 102a in the embodiment of the present invention. The base station 102a includes an antenna 901 for transmitting and receiving a synchronization signal, a synchronization signal transmission unit 902 that performs encoding and modulation processing of the synchronization signal, a synchronization signal reception unit 903 that performs demodulation and decoding processing of the synchronization signal, and an observation A speaker 904 that transmits a signal, an observation signal transmission unit 905 that generates an observation signal, a microphone 906 that receives the observation signal, an observation signal reception unit 907 that detects reception of the observation signal, and a ceiling A control unit 908 that calculates a distance, extracts information multiplexed on a synchronization signal, determines whether a received observation signal is a direct wave or a reflected wave, and generates a report content to the server; A wired transmission unit 909 and a wired reception unit 910 that are necessary for communicating with each other, and a timer 911 that is necessary for measuring the transmission / reception timing of the synchronization signal and the observation signal.

  Here, a sound wave or an ultrasonic wave is assumed as the observation signal, and the speaker 904 and the microphone 906 are used as the constituent elements. However, when the observation signal is wireless, the observation signal transmission unit 905 is the same as the synchronization signal transmission unit 902. The observation signal receiving unit 907 has the same configuration as the synchronization signal receiving unit 903.

  FIG. 10 shows an algorithm explanatory diagram of the base station control unit in the embodiment of the present invention. First, an internal variable COUNT relating to the number of times of receiving an observation signal of MODE = 2 is initialized with 0, and a synchronization signal standby state is entered (1001).

  Next, when a synchronization signal is received (1002), the reception time T1 of the synchronization signal is recorded using a timer (1003).

  Further, by demodulating and decoding the information of the synchronization signal, the identifier ID of the node or base station that transmitted the synchronization signal, the identification information MODE of the observation signal, the transmission period Td of the observation signal, the distance b between the node and the ceiling, etc. Extract (1004).

  Next, an observation signal reception timeout time is set as a waiting time until an observation signal that should arrive after the synchronization signal is received (1005).

  When the reception time-out time has elapsed (1007), the process returns to standby for a synchronization signal (1002).

  When the observation signal is received within the reception timeout period (1006), the reception time T2 of the observation signal is recorded (1008).

  Next, a time difference is obtained from the reception time of the synchronization signal and the reception time of the observation signal, and this is calculated as the distance d (1009).

  It is checked whether or not the observation signal is transmitted with MODE = 2 (1010).

  If it is not MODE = 2, it is checked whether or not the transmission is made with MODE = 0 (1011). If it is transmitted with MODE = 0, if the ID of the synchronization signal is the same as the ID of the base station itself, the distance d determined above is stored as the distance a from the base station to the ceiling (1012). ), The process returns to standby for a synchronization signal (1002).

  If it is not the one transmitted with MODE = 0 at 1011, it is checked whether it was transmitted with MODE = 1 (1013). If MODE = 1 is not satisfied, MODE outside the setting is designated, so that nothing is done and the process returns to waiting for a synchronization signal (1002).

  In 1013, when MODE = 1, it is assumed that a direct wave has been received, the fact that the direct wave has been detected, the distance a between the base station and the ceiling, the distance b between the node and the ceiling, and the distance d measured from the node to the base station are Report to the server (1014).

  In 1010, if MODE = 2, it is checked whether or not the internal variable COUNT = 1 (1015). When COUNT = 1 is not satisfied, COUNT = 1 is set (1016), T_last = T1 is substituted for the variable of the time T_last at which the synchronization signal was last received (1017), and the process returns to the standby for the synchronization signal (1002).

  If COUNT = 1, the internal variable COUNT = 0 is initialized (1018).

  It is checked whether the difference between the reception timing T1 of the synchronization signal and the reception timing T_last at which the observation signal was received with the synchronization signal of MODE = 2 last time is approximately twice the transmission period Td of the observation signal (1019). .

  When the transmission period is approximately twice at 1019, it is determined that the observation signal of MODE = 2 has been continuously received and that the observation signal of MODE = 1 has not been received, and is determined as a reflected wave. The server reports to the server that the reflected wave has been detected, the distance a between the base station and the ceiling, the distance b between the node and the ceiling, and the distance d measured from the node to the base station (1020).

  If it is not about twice the transmission cycle in 1019, the process returns to waiting for a motivation signal (1002).

  However, in a system that performs position detection based on a time difference of arrival (TDoA), as information to be notified to the server, reception time information T2 of the observation signal is notified to the server instead of the information of the distance d.

  FIG. 11 shows a configuration diagram of a server in the embodiment of the present invention. The server 101 uses the base station position data 1105 storing the coordinates of the base station, the measurement data 1106 storing the data collected from the base station, and the direct wave using the base station position data 1105 and the measurement data 1106. The position calculation processing unit 1101 that calculates the node position of the position detection target after distinguishing the reflected wave and correcting the distance, stores the data collected from the base station, and receives a request from a surrounding client. The control unit 1102 performs position calculation protocol processing for executing calculation and returning an execution result, and a wired transmission unit 1103 and a wired reception unit 1104 necessary for communication with the base station.

  FIG. 12 shows a measurement database configuration diagram of the server in the embodiment of the present invention. The measurement data includes the identifier ID of the node that transmitted the observation signal, the identifier ID of the base station that received the observation signal, an identifier indicating whether the route is a direct wave or a reflected wave, and the distance from the base station to the ceiling a, a distance b from the node to the ceiling, and a distance d from the node to the base station. However, in a system that performs position detection using a time difference of arrival (TDoA), reception time information t of an observation signal is stored instead of information on distance d.

  Next, calculation in the position calculation processing unit 1101 will be described. The coordinates of the position detection target node are (x, y), and the coordinates of the surrounding base stations 102a, 102b, and 102c are (xa, ya), (xb, yb), and (xc, yc), respectively.

  When the distances measured from the node 103 to the base stations 102a, 102b, and 102c are da, db, and dc, respectively, and the results of correction by Equation 2 are da ', db', and dc ', Find (x, y) that minimizes F.

  In a system that performs position detection using a time difference of arrival (TDoA), reception time information t of an observation signal is used instead of information on distance d. At this time, if the measured time information is ta, tb, tc, the following equation 4 is established.

  Here, c represents the speed of light. By solving these simultaneous equations, the distance from the node 103 to the base stations 102a, 102b, and 102c is converted, and then the correction of Expression 2 is performed, and the node position that minimizes the error F of Expression 3 similarly ( x, y) can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS The structure of the radio | wireless communications system concerning this invention, and the system block diagram for performing the position detection of a node. Explanatory drawing regarding the influence of the reflected wave used as the subject of the radio | wireless communications system concerning this invention. The comparison figure regarding the measurement distance of the direct wave and reflected wave in the radio | wireless communications system concerning this invention. Explanatory drawing of the method of estimating the distance between a node and a base station from the distance measured with the reflected wave in this invention. Explanatory drawing of the procedure which calculates | requires the node position in this invention. Explanatory drawing regarding the determination method of the reflected wave in this invention. The block diagram of the node in this invention. Explanatory drawing of the method of calculating | requiring the transmission output which does not pick up the reflected wave from the ceiling in this invention. The block diagram of the base station in this invention. The algorithm explanatory drawing of the base station control part in this invention. The block diagram of the server in this invention. The measurement database block diagram of the server in this invention.

Explanation of symbols

101 server, 102a, 102b, 102c base station, 103 nodes, 104 LAN, 105 ceiling, 201 obstacle,
701 antenna, 702 synchronization signal transmission unit, 703 synchronization signal reception unit, 704 speaker, 705 observation signal transmission unit, 706 transmission output control unit, 707 microphone, 708 observation signal reception unit, 709 reception amplitude measurement unit, 710 control unit, 711 Timer,
901 antenna, 902 synchronization signal transmission unit, 903 synchronization signal reception unit, 904 speaker, 905 observation signal transmission unit, 906 microphone, 907 observation signal reception unit, 908 control unit, 909 wired transmission unit, 910 wired reception unit, 911 timer,
1101 Location calculation processing unit, 1102 control unit, 1103 wired transmission unit, 1104 wired reception unit, 1105 base station location data, 1106 measurement data.

Claims (7)

In a position detection system for detecting a node position of a wireless communication system,
A position detection system having a position detection target node, a base station around the node, a reflector on a signal arrival path between the node and the base station, and a server for calculating the node position,
The node has a means for transmitting a synchronization signal for time synchronization between the node and the base station, a means for transmitting an observation signal for measuring the distance between the node and the base station, and a distance between the node and the reflector. Means for calculating the reception amplitude of the observation signal, means for determining the transmission output from which the reflected wave from the reflector cannot be picked up at the node from the observed reception amplitude, and the observation signal below the transmission output And means for placing identification information on the synchronization signal for distinguishing between the case of transmitting the observation signal and the case of transmitting the observation signal at the maximum output,
The base station includes means for receiving a synchronization signal for time synchronization between the node and the base station, means for receiving an observation signal for measuring the distance between the node and the base station, and the base station and the reflector. Means for calculating the distance, a means for transmitting and receiving signals to and from the server for calculating the position, and means for determining whether the observation signal transmitted from the node using the identification information is a direct wave or a reflected wave. Have
The server records means for transmitting / receiving signals to / from the base station, means for collecting measurement data of observation signals between the node and the base station obtained via the base station, the collected measurement database, and the coordinates of the base station. Means for calculating the position of the node using the database
In the base station, it is determined whether the observation signal transmitted from the node is a direct wave or a reflected wave based on the identification information of the synchronization signal, and the server determines whether the observation signal is a direct wave or a reflected wave. A position detection system characterized by correcting a distance.   2. The position detection system according to claim 1, wherein the server transmits / receives a signal to / from the base station, and collects measurement data of an observation signal between the node and the base station obtained via the base station. And a means for calculating the position of the node using the collected measurement database and a database in which the coordinates of the base station are recorded, and whether the observation signal arrival path between the node and the base station is a direct wave or a reflected wave. A position detection system that calculates a position of a node by correcting a distance between the node and a base station using a determination result at the station.   The position detection system according to claim 1, wherein the base station transmits and receives a synchronization signal for time synchronization between the node and the base station, and an observation for measuring a distance between the node and the base station. Means for transmitting / receiving signals, means for calculating the distance between the base station and the reflector, a server for performing position calculation, means for transmitting / receiving signals, and an observation signal transmitted from the node using the identification information is directly And a means for determining whether the wave is a reflected wave or not, and determining whether the observation signal transmitted from the node is a direct wave or a reflected wave based on the identification information of the synchronization signal.   The position detection system according to claim 1, wherein the node transmits and receives a synchronization signal for synchronizing time between the node and the base station, and an observation for measuring a distance between the node and the base station. Means for transmitting / receiving signals, means for calculating the distance between the node and the reflector, means for measuring the reception amplitude of the observation signal, and transmission in which the reflected wave from the reflector cannot be picked up at the node from the observed reception amplitude Means for determining output, and means for placing identification information on the synchronization signal for distinguishing between the case of transmitting the observation signal below the transmission output and the case of transmitting the observation signal at the maximum output, and below the transmission output A position detection system characterized by alternately repeating an observation signal transmission and an observation signal transmission at maximum output.   5. The position detection system according to claim 4, wherein when the node measures the distance between the node and the reflector in the means for determining a transmission power at which the reflected wave from the reflector cannot be picked up at the node. , Transmit the observed signal transmission output at the maximum, measure the reception amplitude of the observation signal received after being reflected by the reflector, examine the relationship between the transmission output and the reception amplitude in advance, and check this relationship, A position detection system characterized by obtaining a transmission output that is a reception determination threshold capable of receiving an observation signal.   5. The position detection system according to claim 4, wherein the node transmits the observation signal at the maximum transmission output, confirms that the observation signal reflected by the reflector is received, and then transmits the transmission output by reducing the transmission output by a certain value. A position detection system characterized by determining whether or not an observation signal can be received and continuously reducing the transmission output of the observation signal until no observation signal is received, thereby obtaining a transmission output that does not pick up the reflected wave from the reflector. A position detection method in a position detection system for detecting a node position of a wireless communication system, comprising:
The position detection system includes a position detection target node, a base station around the node, a reflector on a signal arrival path between the node and the base station, and a server for calculating the node position,
The node has a means for transmitting a synchronization signal for time synchronization between the node and the base station, a means for transmitting an observation signal for measuring the distance between the node and the base station, and a distance between the node and the reflector. Means for calculating the reception amplitude of the observation signal, means for determining the transmission output from which the reflected wave from the reflector cannot be picked up at the node from the observed reception amplitude, and the observation signal below the transmission output And means for placing identification information on the synchronization signal for distinguishing between the case of transmitting the observation signal and the case of transmitting the observation signal at the maximum output,
The base station includes means for receiving a synchronization signal for time synchronization between the node and the base station, means for receiving an observation signal for measuring the distance between the node and the base station, and the base station and the reflector. Means for calculating the distance, a means for transmitting and receiving signals to and from the server for calculating the position, and means for determining whether the observation signal transmitted from the node using the identification information is a direct wave or a reflected wave. Have
The server records means for transmitting / receiving signals to / from the base station, means for collecting measurement data of observation signals between the node and the base station obtained via the base station, the collected measurement database, and the coordinates of the base station. Means for calculating the position of the node using the database
In the base station, it is determined whether the observation signal transmitted from the node is a direct wave or a reflected wave based on the identification information of the synchronization signal, and the server determines whether the observation signal is a direct wave or a reflected wave. A position detection method comprising correcting a distance.

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