JP2010041254A - Enhanced room separation in wlan-based rtls and its method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wireless location information system for tracking wireless tags and detecting the locations of the wireless tags in a structure having defined areas that allows differentiation between the defined areas. <P>SOLUTION: The wireless location information system includes at least one ultrasonic transmitter, which is placed in each of defined areas so as to transmit an ultrasonic signal having area identification information and/or transmitter ID information, and a plurality of wireless tags 102 respectively which transmit the latest area identification information and/or transmitter ID information, received and accepted by each wireless tag, as a tag message. A plurality of location information receivers 110 are introduced in the structure so as to receive the tag message and to notify it to a common server together with parameters obtained by arbitrarily measuring the messages received from the tags. The common server uses the defined area or the transmitter ID notified from each wireless tag in order to determine the location of each wireless tag in the structure. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

RELATED APPLICATIONS This application is based on US Pat. No. 6,968,194 “METHOD AND SYSTEM FOR LOCATION FINDING IN A WIRELESS LOCAL AREA NETWORK” (November 22, 2005). Issued), US Pat. No. 6,963,289 “WIRELESS LOCAL AREA NETWORK (WLAN) CHANNEL RADIO-FREQENCY IDENTIFICATION (RFID) TAG SYSTEM AND METHOD THEREFER (Wireless Local Area Network (WLAN)) Channel Radio Frequency Identification (RFID) And its method) "(issued November 8, 2005), and Related to national Patent Application No. 11 / 466,540 "ENHANCED AREA SEPARATION IN WIRELESS LOCATION SYSTEMS SYSTEM AND METHOD (enhanced and method distinguish areas in a wireless location system)" (August 8, 2006 filed). All of the above references are assigned to the same assignee, the contents of which are hereby incorporated by reference.
The present invention relates generally to wireless local area networks (WLANs), and more specifically, real-time location information of assets, as well as accurate rooms where assets are located at a given time, with high reliability and The present invention relates to a WLAN location information system provided with accuracy.

  In many places where a real-time location system has been introduced, it is important not only to know the real-time location information of the asset, but also to know the exact room number where the asset is located at a given time and with high reliability. This is particularly necessary on the floors of large buildings that are divided into many small rooms, such as hospital buildings.

  A standard WLAN-based real-time location information system (RTLS) uses radio signals to calculate the location of the device. Here, RSSI (remote signal strength indication) or TOA (arrival time) of a radio signal transmitted by a normal tag is measured. The signal is received at several location information receivers or access points at various locations. Special geometric and mathematical algorithms are then implemented and the location of the device is calculated. For a detailed description of these systems and methods, reference may be made to the aforementioned patent application documents.

  Even today's such systems can achieve highly accurate location information (less than 1-2 meters), but current systems provide the best solution to know the exact room location / number There is a problem to do. This feature is called “room distinction”. Thus, an asset located in one room may be mistakenly recognized as being on the other side of the wall, i.e., an adjacent room. This occurs because of the fact that wireless signals can penetrate walls and the system may not be “sensitive” to the presence of walls.

  The main issues (requirements) concerning the room distinction are as follows. (1) Realizing almost 100% room distinction, notifying the user of the accurate room location information of the asset, and very unlikely to detect that the asset is in the wrong room; (2) Maintain other benefits of WLAN-based real-time location information systems, such as location information functions, outdoor location information, telemetry, and (3) achieve the above with minimal additional cost per room .

  The usual solution to the “room distinction” problem is to use low frequency wireless communication. That is, a low-frequency transmitter (sometimes called an exciter) periodically transmits a beacon signal including room number information. The tag is activated by a low frequency transmission and begins to function, sending a WLAN message notifying the system of the exciter ID and / or room number. Since the exciter is located at the entrance of the room, it activates all tags that enter the room. In other scenarios, the exciter is located on the inner wall of the room, so that the signal radiation is tuned to be received at almost every location in the room and only inside the room. For a more detailed description of these systems and methods, reference may be made to the aforementioned patent application documents.

  The above system solves the requirement (2). That is, the WLAN RTLS is complete. However, the above requirement (3) is not sufficiently satisfied. That is, due to the cost of the exciter, it is difficult to achieve a relatively low cost solution per room. Furthermore, 100% room distinction (the above requirement (1)) cannot always be realized. The reasons for this may be: (a) it may be very difficult to adjust the exciter to receive at each point in the room and only inside the room, and (b) the situation entering and leaving the room It is difficult to distinguish the situation because it complicates the overall system solution.

  The use of ultrasound is another way to achieve room differentiation. This is because the ultrasonic wave freely spreads in the vacant space but does not penetrate the wall. Existing real-time location systems that utilize ultrasound include a tag transmitter and one or more ultrasound receivers connected to a network and are attached to the interior walls and ceiling of the room. The tag always transmits an ultrasound signal, and the receiver notifies the network of the signal level and / or tag ID, thereby identifying the room in which the tag is transmitting. Since the ultrasonic signal transmitted by the tag is received only by the receiver in the same room as the tag, it is easy to determine an accurate room to some extent. Although it is possible to determine accurate position information in the room, it is quite difficult.

  This system solves the above requirement (1). It provides an excellent way to achieve almost perfect room differentiation. However, since the ultrasound system is an independent system that requires its own infrastructure, it does not meet the requirement (2) above and includes all the benefits that users enjoy using a standard WLAN infrastructure for location-based systems. I can't. Furthermore, the requirement (3) is not satisfied. This is because the total cost of the solution increases because it requires a unique infrastructure in addition to the WLAN infrastructure. Each room requires several receivers, and the total cost of each room is relatively high.

  Therefore, there is a need to provide a system and method that overcomes the above problems. The system and method allow for WLAN-based location information and services as well as distinguishing rooms using ultrasound signals. The combination of the two technologies and an integrated structural method can meet all the room differentiation requirements mentioned above in a very efficient way.

  In accordance with one embodiment of the present invention, a wireless location information system is disclosed. This wireless location information system is used for tracking and location detection of wireless tags in a structure having defined areas so that distinctions can be made between defined areas. The wireless location system has at least one ultrasound transmitter located in each of the defined areas and transmits an ultrasound signal having area identification and / or transmitter ID information. A plurality of wireless tags are provided, and each wireless tag transmits the latest area identification information or the latest transmitter ID received and accepted by the wireless tag in a tag message. A plurality of location information receivers and / or WLAN access points are introduced into the structure to receive the tag message and notify the common server of the message received from the tag along with optionally measured parameters. The server also uses the definition area or transmitter ID notified from each wireless tag to determine the location of each wireless tag in the structure.

  According to another embodiment of the present invention, a method is disclosed that enables tracking and location detection of a wireless tag within a defined area of a structure and distinguishing between defined areas. The method comprises providing a location information receiver and / or a WLAN access point introduced in the structure to detect the location of the wireless tag, and transmitting at least one ultrasonic transmission to each defined individual area. An ultrasonic signal is transmitted from each of at least one ultrasonic transmitter of each defined individual area, each ultrasonic signal being limited to the defined individual area to be transmitted, The sonic signal has area identification information and / or transmitter ID, and has radio identification tag and / or transmitter ID in the range covered by at least one ultrasonic transmitter in a defined individual area Receives ultrasonic signals and transmits tag messages from wireless tags in the coverage area. Tag messages are received by wireless tags. Latest identification information (area identification and / or transmitter ID) and a wireless tag identification data that is accepted is contained be incorporated.

  According to another embodiment of the invention, a wireless tag is disclosed. The wireless tag has an ultrasonic receiver module for receiving an ultrasonic signal having area identification and / or transmitter ID information. The transmitter is prepared to transmit the area identification and / or transmitter ID information received and accepted by the wireless tag and the identification number of the wireless tag. The memory is provided for storing at least an identification number (area and / or transmitter ID). The microprocessor is coupled with the memory, the ultrasonic receiver module, and the transmitter. The power supply device is prepared for supplying power to the circuit of the wireless tag.

  The invention is best understood by reading and referring to the following detailed description in conjunction with the accompanying drawings.

  Common reference symbols are used throughout the drawings and the detailed description to refer to the same elements.

  With reference to the figures, an embodiment of a wireless network 100 of the present invention is disclosed. The network 100 is a wireless position information system that provides, in addition to real-time position information of assets, an accurate room where the assets are located at a predetermined time with high reliability and accuracy.

  The network 100 uses a standard wireless tag 102. In FIG. 1, six different tags 102 are shown. However, this is for illustrative purposes only and is not intended to limit the scope of the present invention. According to one embodiment, tag 102 is a WLAN-based tag. However, the present invention can be implemented in tags 102 as well as any standard wireless client operating on such a network. For simplicity, whenever reference is made to tag 102 in this application, it also applies to WLAN mobile units or WLAN standard clients, and vice versa.

  The tag 102 is used in the wireless location information system 104. Wireless location information systems can include WLAN-based location information systems and the like. Other types of wireless location information systems can be used without departing from the spirit and scope of the present invention. The following description is written for a WLAN-based system. However, this should not be construed as limiting the scope of the invention. As shown in FIG. 1, the wireless location information system 104 receives a message transmitted from the tag 102 using a plurality of location information receivers and / or access points 110 arranged everywhere in FIG. it can. However, as mentioned above, room distinction is a problem. The location of each tag 100 is based on information notified from the position information receiver and / or access point 102 corresponding to each tag 100, and a server connected to the position information receiver and / or access point 102. (Not shown in FIG. 1). As described above, if this location is calculated based only on the parameters measured with the RF radio signal, there is a possibility that an erroneous room is detected to some extent.

  In order to overcome the problem of room distinction, each tag 102 is equipped with an ultrasonic receiver module 106 (see FIG. 3). Once activated by an ultrasound signal transmitted from an ultrasound signal (US) transmitter 108, including a room and / or transmitter ID number, the tag 102 includes a room and / or transmitter ID and a specific tag A WLAN radio message (RM) that associates 102 with a particular room is sent to the network 100.

  In accordance with one embodiment of the present invention, one or more ultrasound-based transmitters 108 are located inside the room and are periodically placed in the room ID (ie, area number 1, area number 2, etc.) or any other The ultrasonic signal (US) including the identification information (for example, transmitter ID) is transmitted. Due to the non-penetrating nature of the ultrasonic signal (US), the tag 102 is activated only by the ultrasonic signal (US) of the transmitter 108 placed inside the room where the tag 102 is located. Since the ultrasonic signal (US) cannot penetrate the wall of the room, the tag 102 placed outside the room is not activated. Due to the propagating property of the ultrasonic signal (US) inside the sealed structure, the ultrasonic signal is received regardless of the position and angle of the tag 102 in the room. In FIG. 1, it should be noted that, generally, the door is used in the entrance / exit area of the room, so activation of the tag 102 opposite the entrance / exit area of the room by the ultrasonic signal (US) is avoided. Therefore, tag number 2 in area 2 in FIG. 1 does not receive an ultrasonic signal (US) transmitted from transmitter 108 in area number 1.

  The tag 102 can measure the TOA (arrival time) of several ultrasonic signals (US) received by the tag 102, and the information is a location information server and uses TDOA (incoming time difference) to determine the exact location Can be used to detect It is also possible to measure the ultrasonic signal TOA and the LF signal TOA with an accuracy of +/− 1 millisecond and calculate the distance of the tag 102 from the transmitter 108 by both signals transmitted from a single transmitter. is there.

  One major advantage of network 100 is that network 100 utilizes the backbone WLAN connection of tag 102 to transmit room and / or transmitter ID and tag ID. Thus, the network 100 does not require any additional network connections or new network infrastructure from the ultrasound unit.

  In another embodiment of the network 100, the accuracy of the location information of the WLAN-based system 104 can be improved, not just providing information about the room where the asset is located. Since the position ID of the asset is limited to the defined area (that is, the defined room area) by the transmission ID sent from the transmitter 108, the coordinates outside the room where the transmission ID is defined by the transmission ID. The position information calculation result can be removed. In another embodiment, since the room information is a subset of the floor information, this additional information can be used to prevent detection of assets on the wrong floor (floor distinction). In another embodiment of the method, room and / or transmitter ID information may be used to filter some WLAN location information receiver 110 readings. Such an error factor (such as interference with a specific position information receiver) can be removed, and the accuracy of the entire position coordinates calculated by the WLAN system 104 is further improved.

  Referring now to FIG. 3, one or more ultrasonic microphones 112 are incorporated into the tag 102 according to one embodiment. The ultrasonic microphone 112 is connected to an ultrasonic receiver module 106 that can acquire data from the received ultrasonic signal (US). The transmission ID of the ultrasonic signal (US) is sent to the microprocessor 120. A periodic ultrasonic signal (US) in the air activates a transmitter 114 that transmits relevant information (eg, room ID and / or transmitter ID) through the WLAN-based location information system 104. Alternatively, the information can be stored in memory 116 of tag 102 and transmitted in the next session of tag 102 WLAN transmission. Signals transmitted over WLAN are typically transmitted periodically at predefined intervals, and further include broadcast address, sequence number, and other information related to the tag including tag ID and telemetry information It is. The transmission signal includes, at a minimum, an identification number associated with the tag 102 obtained from the memory 116, and can further store instructions and data of the microprocessor 120.

  The sensor circuit 122 can be coupled to the signal processor 120 and receive signals from the external sensor connector 124 or the internal sensor 126, and the battery condition monitoring circuit 128 can also be coupled to the signal processor 120 to increase the strength of the power supply device 130. Can show. The battery condition monitoring circuit 128 and sensor circuit 122 provide the signal processor 120 with the tag ID and information that can be transmitted to the location information receiver and / or access point 110 of the WLAN-based location information system 104.

  A sniffer circuit 132 may be incorporated to determine if the WLAN channel is clear. If the WLAN channel is clear, the transmission signal is transmitted at a preset time, otherwise the backoff algorithm specified in the specific WLAN specification employed in the WLAN is applied and the signal Is sent after the channel is cleared. Alternatively, the sniffer circuit 132 can be omitted. In such a case, the transmitted signal is distinguished from the standard WLAN signal by using a non-standard code sequence or non-standard preamble.

  In another embodiment of the present invention, the tag 102 can utilize an existing low frequency receiver 134 (such as that used in the exciter solution described above) for the purpose of receiving an ultrasonic signal (US). This is because the low frequency receiver 134 normally operates in the same frequency band (40 KHz to 200 KHz). Both the ultrasonic microphone 112 and the low frequency antenna 134A of the low frequency receiver 134 can be connected to the low frequency receiver 134 in parallel as two antennas, and the tag 102 can include both options.

  According to another embodiment of the present invention, the tag 102 can be activated with a low frequency radio signal that is synchronized with an ultrasound signal (US) on the transmitter side. In this embodiment, since the propagation speed of the ultrasonic wave is slower than that of the radio wave, this synchronization is used to measure the time delay between the radio signal and the ultrasonic signal (US), so that the tag 102 and the transmitter 108 are connected. Can be calculated. This information can be transmitted through the WLAN-based location information system 104 and can be used for various purposes regarding location, such as improving location in a room. In any case, the tag 102 is a device that is very sensitive to power supply, so that even if the tag 102 has an ultrasonic receiver side, having no ultrasonic transmitter enables low power consumption. And battery life will be longer.

  In certain embodiments of the system, the tag 102 can have a reception window in which the low frequency receiver 134 is periodically activated to detect the presence of an ultrasound signal. The low frequency receiver 134 can be activated from idle (power saving mode) or from a fully powered off state. This feature can be used to reduce the overall power consumption of the tag 102 and extend battery life. This function is important because reception of a message is a task that consumes power for the tag 102 because propagation of the ultrasonic signal is slow.

  In another embodiment of the present invention, the low frequency exciter can be placed at the entrance of an area where there are many rooms, and the ultrasonic reception at the tag 102 when the tag 102 enters or exits the area. Can be used to start / stop the machine 106 (always or periodically start / stop a periodic reception interval). This is used to extend the battery life of the tag. Therefore, the ultrasonic receiver 106 is completely stopped during a time period that is not located in a part of the place where the ultrasonic area needs to be distinguished. In another embodiment, the exciter can be used to change the ultrasonic reception interval of the tag rather than simply starting / stopping the ultrasonic receiver.

  In another embodiment of the invention, tag 102 may have its own wireless network receiver (bidirectional tag). In systems where the tag's location can be recognized by other means (such as RF-based location), the system can receive an ultrasonic receiver when the tag enters or exits an area that needs to be distinguished from the ultrasound area. A command to activate / deactivate 106 (or periodic receive window) is sent to the tag 102 via the RF receiver.

  Referring now to FIG. 4, the ultrasonic transmitter 108 incorporates an ultrasonic transducer 108A that is used to periodically transmit ultrasonic signals. Microprocessor 108C can be used to determine when to transmit an ultrasonic signal (US). The data payload of the ultrasonic signal (US) incorporates a room ID or any other identification information (for example, transmitter ID). In one preferred embodiment, the ultrasonic transmitter 108 incorporates a power supply device 108D. The power supply device can be an electrical plug, whereby the transmitter 108 can be mounted on a wall surface to obtain a power source for transmitter operation. Alternatively, the power supply device 108D can be operated by a battery or directly connected to an electric circuit such as a ceiling light. Alternatively, by installing several transmitters 108 inside the same room and transmitting the same data in all, a very large sealed structure can be reliably covered.

  The room ID (or any other associated ID) can be manually set on transmitter 108 (eg, using DIP switch 108E) or using any other interface, such as serial connector 108F. Can be set.

  In another embodiment of the present invention, the transmitter 108 connects to the WLAN-based location information system 104 for network setting purposes (such as setting room ID and output power), or PoE (Power over Ethernet (registered trademark)). ) A wired network (for example, Ethernet (registered trademark), etc.) can be connected for power supply by the switch. The network configuration (wired or wireless) gives the user more flexibility during installation and maintenance. When using a WLAN connection, incorporating the optional wireless transceiver 108G in the transmitter unit allows the microprocessor 108C in the ultrasonic transmitter unit 108 to connect to the WLAN-based location information system 104, thus OTA. (Over The Air) can be set and controlled.

  According to another embodiment of the transmitter 108, the transmitter 108 is integrated with a low frequency transmitter 108B, such as the exciter described above, to form an ultrasonic exciter. This allows synchronization between the ultrasonic beacon and the low frequency radio beacon so that, for reasons of power consumption, tag activation on low frequency radio is desirable for such activation desirable tags. It becomes possible.

  In this embodiment, a plurality of speakers can be incorporated into the ultrasonic exciter. In a standard embodiment, there should be one speaker on the front of the box and up to four speakers on each side. All speakers transmit simultaneously or sequentially. Each speaker can be activated or deactivated. The amplitude and phase of each speaker can also be controlled and can be set to any level between zero and the maximum available power. With this feature, you can increase the degree of freedom of mounting the ultrasonic exciter at various locations in the room, optimize the coverage over the entire volume of the room, and from the opening of the room, such as doors and windows. Reduce leakage.

  In various embodiments of the present invention, the transmission frequency of the ultrasonic exciter can be varied from 20 KHz to 200 KHz. The higher the frequency, the greater the propagation loss. Therefore, the higher frequency can be used when the positional information accuracy is more strict. In other embodiments, various frequencies can be used to avoid interference with the receiver of tag 102 (such as interference due to other nearby US sources). Interference avoidance can be performed by changing the frequency dynamically or statically.

  In certain embodiments of the invention, ultrasonic exciters (or hybrid LF + ultrasonic exciters) can be daisy chained together. Use a chain connection and transmit all exciters at the same time (so that the spatial phase is correlated between the exciters) to broaden or optimize the coverage of the ultrasound signal in a particular space Can do. In another embodiment, the ultrasonic exciters can be synchronized so that each ultrasonic exciter can transmit at different time intervals. By using this, it is possible to avoid radio wave interference between transmissions by several ultrasonic exciters in the same room, and to create a high resolution area distinction in the same room.

  In a standard embodiment of the invention, the state of the ultrasonic exciter is monitored. This monitoring operation can detect the transmitted signal by incorporating a self-test mechanism or a reduced range ultrasonic receiver (such as a receiver used in a tag) inside the exciter itself. The indication of monitoring can be done within the exciter (eg, by turning on the LED) or through a network connection of exciters.

  In a preferred embodiment of the present invention, the US exciter can be designed into a box with an AC power outlet built into the back of the box so that it can be installed and powered by simply plugging the exciter into the socket. This enables a solution that combines simple installation and power supply.

  The present invention can also be implemented in any wireless-based WLAN network. The preferred embodiment is a standard Wi-Fi network, but any other WLAN wireless infrastructure, either standard or proprietary, can be used to implement the present invention.

  The present invention satisfies all three requirements of “room distinction”. In the present invention, almost 100 percent room discrimination is achieved by introducing ultrasound signals into the system. Since the system is based on the WLAN real-time location system, all the advantages of the WLAN location system, including the use of existing infrastructure, location accuracy, WLAN-based services, and telemetry use, etc. Retained. The total cost per room is kept low due to fewer additional components required for the tag, the low cost and simplicity of the ultrasound transmitter unit, and the use of existing network infrastructure. The present invention can be easily implemented and is effective. The above advantages are realized in implementations that are naturally combined into a WLAN location system with minimal additional cost to existing components and minimal impact on tag battery life.

  The present disclosure provides exemplary embodiments of the present invention. The scope of the invention is not limited to these exemplary embodiments. Numerous variations, whether explicitly provided herein or implicitly provided herein, include structure, dimensions, material types, variations in the manufacturing process, etc. Those skilled in the art in view of the present disclosure can implement.

It is a general view which has a system of the present invention. FIG. 2 is a simple block diagram illustrating the system of FIG. 1. It is a simple block diagram of the wireless tag used by this invention. It is a simple block diagram of the ultrasonic transmitter used by this invention.

Claims (26)

A wireless location information system for tracking a radio tag and detecting a location in a structure having the defined area so that a distinction between defined areas can be made,
At least one ultrasound transmitter located in each of the defined areas for transmitting an ultrasound signal having data including identification information or transmitter ID of at least one area;
A plurality of wireless tags, each of which transmits data including at least one of the latest area identification information or transmitter ID received and accepted by the wireless tag in a tag message;
A plurality of location information receivers introduced in the structure for receiving the tag message and notifying the received tag message and measured parameters;
A wireless location information system comprising: a server that receives the tag message and the measured parameter and determines a location and a definition area of each wireless tag.   The wireless location information system according to claim 1, wherein the plurality of location information receivers are WLAN access points.   The wireless position information system according to claim 1, wherein the ultrasonic signal activates each wireless tag and transmits the identification information in a tag message.   The wireless location information system according to claim 1, wherein the area identification information is stored in each tag and transmitted in a next transmission session of each tag.   The wireless location information system according to claim 1, wherein the at least one ultrasonic transmitter periodically transmits the ultrasonic signal having area identification information.   The wireless location information system of claim 1, wherein the at least one ultrasonic transmitter further transmits a low-frequency wireless signal that is synchronized with the ultrasonic signal. Each of the plurality of wireless tags is
An ultrasonic receiver module for receiving the ultrasonic signal having area identification information;
The wireless location information system according to claim 1, further comprising a transmitter for transmitting the area identification information received and accepted by the wireless tag. Each of the plurality of wireless tags is
A memory for storing at least the identification number of each individual tag;
A microprocessor coupled to the memory, the ultrasonic receiver module, and the transmitter;
The wireless location information system according to claim 7, further comprising: a power supply device for supplying power to each individual tag circuit. Each of the plurality of wireless tags is
A sniffer circuit coupled with the signal processor for determining whether a channel is clear for the transmitter to transmit;
The wireless position information system according to claim 8, further comprising a power supply state monitor for monitoring a state of the power supply device. The ultrasonic receiver module is
An ultrasonic microphone,
The wireless location information system of claim 8, comprising an ultrasonic receiver coupled to the ultrasonic microphone and the signal processor.   The wireless location information system of claim 10, wherein each of the plurality of wireless tags further comprises a low frequency receiver coupled with the signal processor. A method for tracking a radio tag and detecting a location within the defined area structured to distinguish between defined areas, comprising:
In order to detect the location position of the wireless tag, comprising a position information receiver introduced in the structure;
Introducing at least one ultrasonic transmitter in each of the defined areas;
Transmitted by each of the at least one ultrasound transmitter in each of the defined areas is an ultrasound signal limited to the defined individual area to be transmitted and having at least one of area identification information or transmitter ID. To do
Receiving the ultrasound signal having at least one of the area identification information or transmitter ID by means of a radio tag within a range of the at least one ultrasound transmitter of the defined individual area;
Transmitting a tag message incorporating at least one of the latest identification information or transmitter ID received and accepted by the wireless tag and the wireless tag identification data from the wireless tag within a coverage area;
Including methods.   The method of claim 12, wherein the location information receiver is a WLAN access point.   The method according to claim 12, wherein the ultrasonic signal activates the wireless tag and transmits the identification information in the tag message. Storing the area identification information in the wireless tag;
The method of claim 12, further comprising transmitting the tag message in a next transmission session of the wireless tag.   The method of claim 12, wherein transmitting the ultrasound signal further comprises transmitting the ultrasound signal periodically.   The method of claim 12, further comprising transmitting a low frequency radio signal synchronized with the ultrasound signal by the at least one ultrasound transmitter. An ultrasonic receiver module for receiving an ultrasonic signal having at least one of area identification or transmitter ID information;
A transmitter for transmitting at least one of the area identification or transmitter ID information received and accepted by the wireless tag, and an identification number of the wireless tag;
A memory for storing at least the identification number;
A microprocessor coupled to the memory, the ultrasonic receiver module, and the transmitter;
A wireless tag comprising a power supply device for supplying power to a circuit of the wireless tag. A sniffer circuit coupled with the signal processor for determining whether a channel is clear for the transmitter to transmit;
The wireless tag according to claim 18, further comprising a power supply state monitor for monitoring a state of the power supply device. The ultrasonic receiver module is
An ultrasonic microphone,
The wireless tag of claim 18, comprising an ultrasonic receiver coupled to the ultrasonic microphone and the signal processor.   24. The wireless tag of claim 20, wherein each tag further comprises a low frequency receiver coupled with the signal processor.   Each wireless tag can measure TOA (arrival time) of a plurality of ultrasonic signals received by each tag, and the measured TOA uses the TDOA to calculate the location of each tag. A wireless location information system for tracking and location detection of a wireless tag in a structure having the defined area that can be distinguished between defined areas as claimed in claim 1 .   The ultrasonic receiver module can measure TOA (arrival time) of a plurality of ultrasonic signals received, and the measured TOA is used in a server to calculate the location of the tag using TDOA. The wireless tag according to claim 18.   The structure having the defined area such that each wireless tag has a receiving window for each tag to be activated to receive the ultrasound signal so as to distinguish between the defined areas according to claim 1. Wireless location information system for tracking wireless tag and detecting location.   The wireless tag according to claim 18, wherein the ultrasonic receiver module has a reception window for receiving the ultrasonic signal when the ultrasonic receiver module is activated.   In a structure having said defined areas such that distinctions between defined areas according to claim 1 can be daisy chained together, location information receivers of the same area defined in advance Wireless location information system for tag tracking and location detection.

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