KR101751805B1 - E-zigbee with complex postioning fuction and device and method for indoor postioning using the same - Google Patents

Abstract

An indoor positioning apparatus according to an embodiment of the present invention includes a tag for generating a wireless signal; Receiving a radio signal from the tag, checking a tag ID and strength of the received radio signal, transmitting a radio signal including a flag to the tag, receiving a radio signal including a flag from the tag, An AP for transmitting transmission / reception time information of a wireless signal including intensity information and a flag; And a positioning server for receiving the radio signal intensity information and radio signal transmission / reception time information from the AP and determining the position of the tag, wherein the tag is a radio signal signal including a flag from the AP, The AP starts time counting of the tag upon reception and ends the time count of the tag when transmitting the radio signal including the flag to the AP, and the AP starts counting time of the AP when transmitting the radio signal including the flag to the tag And terminates the time counting of the AP upon receiving the radio signal including the flag from the tag.

Description

TECHNICAL FIELD [0001] The present invention relates to an indoor positioning apparatus and an indoor positioning method using an e-Zigbee,

The present invention relates to an e-Zigbee having an integrated positioning function, an indoor positioning device and an indoor positioning method using the same, more specifically, to improve positioning accuracy through an improved positioning ZigBee tag and a hybrid map DB learning The present invention relates to an indoor positioning apparatus and method.

Among various multimedia communication services, location-based service (LBS), which provides services using location and geographical information, is widely regarded as being widely utilized and convenient.

The location based service (LBS) confirms the current location information by using a satellite-based location confirmation receiving terminal such as GPS, and transmits the route guidance, surrounding information guidance, traffic information, distribution control, , Crime report countermeasures, and location based CRM (Customer Relationship Management).

In order to use such a location-based service, it is necessary to grasp the location of the location confirmation receiving terminal. However, the satellite-based positioning terminal can not provide location information in areas where satellite signals are weak, such as indoors, tunnels, underground parking lots, and urban areas.

In order to solve such a problem, indoor positioning techniques for providing location-based services in areas where satellite signals are weak, such as indoors, have been studied variously. In particular, wireless positioning methods using wireless communication devices such as wireless LAN (WLAN), ultra wideband wireless communication (UWB), spread spectrum (CSS), Zigbee, and Bluetooth have been researched and developed.

In particular, a fingerprint technique for measuring a signal strength between an AP (Access Point) (hereinafter, referred to as 'AP') and a receiving terminal is widely used for indoor positioning based on a wireless communication infrastructure.

The fingerprint method divides the indoor space into virtual lattices and measures the strength of each radio signal for each lattice to form a database in the form of a fingerprint. Then, the received signal strength, RSS ) Is compared with the database to find out the location.

However, in the fingerprint method, since the error range is still large, it is necessary to implement a more accurate indoor positioning method.

The wireless signal may be a short-range wireless communication such as Wi-Fi or Zigbee. In particular, ZigBee's RSS triangulation method is used, but it still needs to be improved because of the error.

A method of using the arrival time of the radio signal in the Zigbee communication can also be considered, but in this case, the error is larger. For example, the bandwidth in ZigBee communication is typically 2 MHz. In this case, when triangulation is performed using the time value, an error of about 37 m occurs.

The principle of error generation is as follows.

Sampling rate for recovering received data is sampled at a speed of 3 to 4 times the bandwidth in a conventional communication system. Therefore, in the case of 2 MHz bandwidth, sampling is performed at 8 MHz. Therefore, when data is detected at 8MHz speed, there is a hardware limitation that the data may be broken due to the sampling error. If the sampling interval is missed, the positioning error occurs due to the propagation speed.

Since the sampling interval is a reciprocal of the frequency, a sampling interval of 0.125us is obtained when the frequency is 8HHz. When the sampling interval is multiplied by the propagation speed (3 * 10 ⁸ m / s), an error of 37.5 m occurs as shown in the following equation (1).

[Equation 1]

d = c * t = 3 * 10 ⁸ * 0.125 * 10 ^-6 = 37.5 m

Recently, a ZigBee chip having a bandwidth of 4 MHz is used. In this case, too, an error of more than 18 m is generated, which is problematic for use in an indoor positioning.

Especially, in case of a ship sinking or a fire in a building, it is necessary to accurately grasp the position of the rescuer in order to construct a rapid structure, so it is necessary to develop a more accurate positioning apparatus.

An object of the present invention is to solve such a problem by providing an e-Ziggee tag with a built-in multi-positioning function and an indoor positioning device capable of improving positioning accuracy through e-Zigbee tag and hybrid map DB learning And an indoor positioning method.

According to an embodiment of the present invention, an e-Zigbee with a built-in complex positioning function generates and transmits a radio signal to an AP, And resumes the retransmission to the AP, wherein the time counting is started when the radio signal is received, and the time counting is terminated when the radio signal is retransmitted.

In one embodiment, the flag may be added to the payload field of the e-Zigbee signal PPDU field.

In addition, an indoor positioning apparatus according to an embodiment of the present invention includes a tag for generating a wireless signal; Receiving a radio signal from the tag, checking a tag ID and strength of the received radio signal, transmitting a radio signal including a flag to the tag, receiving a radio signal including a flag from the tag, An AP for transmitting transmission / reception time information of a wireless signal including intensity information and a flag; And a positioning server for receiving the radio signal intensity information and radio signal transmission / reception time information from the AP and determining the position of the tag, wherein the tag is a radio signal signal including a flag from the AP, The AP starts time counting of the tag upon reception and ends the time count of the tag when transmitting the radio signal including the flag to the AP, and the AP starts counting time of the AP when transmitting the radio signal including the flag to the tag And terminates the time counting of the AP upon receiving the radio signal including the flag from the tag.

In one embodiment, the tag may be an e-Zigbee tag.

In one embodiment, the flag may be added to the payload field of the e-Zigbee PPDU field.

In one embodiment, the tag may simultaneously transmit a time count value of a tag when transmitting an AP with a radio signal including a flag.

In one embodiment, the transmission and reception times of the wireless signal including the flag may include a time count value of the tag and a time count value of the AP.

In one embodiment, the positioning server includes: a wireless communication unit for receiving transmission / reception time information and RSS (Received Signal Strength) of a radio signal including a flag from the AP; A first database storing a time of arrival (ToA) value measured in a predefined area; A parameter storage unit for storing delay parameters generated when wireless communication between the tag and the AP is performed; And calculating a ToA value by subtracting the delay parameter from the time information received by the wireless communication unit, comparing the calculated ToA value with a ToA value stored in the first database, and determining a matching region as the tag position And a determination section.

In one embodiment, the positioning server further includes a second database storing a measured RSS value in a predefined area, and the position determination unit may calculate a comparison result of the calculated ToA value and the ToA value stored in the first database If there are two or more matching regions, the received RSS value may be compared with the RSS value stored in the second database to determine the matching region as the tag position.

In one embodiment, a plurality of APs are arranged in the indoor space, and the APs can sequentially transmit the flag generation command and receive the radio signal including the flag.

Also, an indoor positioning method according to an embodiment of the present invention includes the steps of: an AP receiving a wireless signal from a tag and confirming the ID of the tag and the strength of the wireless signal; The AP transmitting a flagged radio signal to the tag and starting a time count of the AP; The tag receiving a radio signal including a flag and starting a time count of the tag; Transmitting the radio signal including the flag to the AP, terminating the time count of the tag, and transmitting the time count value of the tag to the AP at the same time; The AP receiving the radio signal including the flag and terminating the time count of the AP; Transmitting, by the AP, the transmission / reception time information of the radio signal including the flag and the strength of the radio signal to the positioning server; The positioning server calculating the ToA value using the time information; And comparing the calculated ToA value with a ToA value stored in the first database to determine a matching region as the tag position.

In one embodiment, the time information may include a time count of the AP and a time count value of the tag.

In one embodiment, the radio signal is an e-Zigbee radio signal, and the flag may be added to the payload field of the e-Zigbee PPDU field.

In one embodiment, the step of calculating the ToA value may be calculated by subtracting a delay parameter value generated when performing wireless communication between the tag and the AP in the time information.

In one embodiment, if the calculated ToA value and the ToA value stored in the first database are equal to or more than two, the intensity of the radio signal is compared with the radio signal strength value stored in the second database, Tag position as a tag position.

According to the present invention, the measurement of the strength of the radio signal and the measurement of the arrival time of the radio signal are used together, whereby the position can be measured more accurately in the room.

In addition, according to the present invention, it is possible to add only a flag to a conventional ZigBee signal, to implement it with less cost, and to use it for a long period of time with less battery consumption than other devices.

In addition, according to the present invention, a user can easily use a ZigBee chipset without additional equipment.

1 is a block diagram showing an indoor measuring apparatus according to an embodiment of the present invention.
2 illustrates an example in which a plurality of APs are installed in a room and a tag receives a wireless signal according to an embodiment of the present invention.
3 is a block diagram showing the detailed configuration of the positioning server 30 of Fig.
4A illustrates an AP deployment according to an embodiment of the present invention.
FIG. 4B shows the time count value by AP in FIG. 4A.
5A illustrates an AP deployment in accordance with an embodiment of the present invention.
FIG. 5B shows the time count value for each AP in FIG. 5A.
Figure 6 illustrates a second database according to an embodiment of the present invention.
7 is a schematic view illustrating a process of measuring a wireless signal arrival time between a tag and an AP according to an embodiment of the present invention.
FIG. 8 shows a process of measuring a radio signal arrival time when there are a plurality of APs.
9 shows a method of calculating the arrival time value in consideration of the delay component in the measurement of the radio signal arrival time.
10 is a flowchart of an indoor positioning method according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, wherein like reference numerals are used to designate identical or similar elements, and redundant description thereof will be omitted. The suffix "module" and " part "for the components used in the following description are given or mixed in consideration of ease of specification, and do not have their own meaning or role. In the following description of the embodiments of the present invention, a detailed description of related arts will be omitted when it is determined that the gist of the embodiments disclosed herein may be blurred. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. , ≪ / RTI > equivalents, and alternatives.

Terms including ordinals, such as first, second, etc., may be used to describe various elements, but the elements are not limited to these terms. The terms are used only for the purpose of distinguishing one component from another.

It is to be understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, . On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between.

The singular expressions include plural expressions unless the context clearly dictates otherwise.

In the present application, the terms "comprises", "having", and the like are used to specify that a feature, a number, a step, an operation, an element, a component, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. It will be apparent to those skilled in the art that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof.

FIG. 1 is a block diagram of an indoor positioning device according to an embodiment of the present invention, and FIG. 2 illustrates an example of the indoor positioning device installed in a room.

1, an indoor positioning device includes a tag 10, a plurality of access points 20 (hereinafter referred to as an AP), and a positioning server 30.

The tag 10 transmits and receives wireless signals to and from the AP 20. As the tag 10, a wireless communication tag that performs close-range communication may be used, and an e-zigbee tag is preferably used.

E-ZigBee (e-ZigBee) used in the present invention can overcome the limitation of hardware positioning accuracy by using only the software processing without changing the hardware structure by using an extended protocol that can be used for indoor positioning while using the existing ZigBee chipset Zigbee, and e-zigbee positioning refers to a positioning method using such a ZigBee chipset. Specifically, it refers to a method of improving positioning accuracy by fusing two-position data of the radio wave intensity information and the time information.

And the e-zigbee signal means a signal for adding ZigBee-based positioning measurement flags and positioning data packets. A flag for positioning can be added to the packet.

ZigBee is a standard technology for configuring and communicating private networks using small, low power digital radios and is based on the IEEE 802.15 standard. The ZigBee device transmits data to the destination via several intermediate nodes using a mesh network, which allows a wide range of communication to be performed despite low power. Because ZigBee communicates at low power compared to other local area networks, it guarantees a relatively long battery life. In addition, since the ZigBee standard is relatively simple and inexpensive compared to other WPAN technologies such as Bluetooth and Wi-Fi, the present invention can be implemented at low cost when using ZigBee.

In order to improve positioning performance, it can be used in various other chipsets besides ZigBee. In case of ZigBee, it is possible to implement low-cost positioning device because it can be operated at low cost and low power as compared with chipset. In particular, the e-zigbee according to the present invention can be implemented without adding any additional hardware to the existing ZigBee chipset, thereby realizing an improved positioning apparatus at a low cost.

A plurality of the APs 20 may be installed in the room, and four APs 22, 24, 26, and 28 are provided in the present embodiment, but the present invention is not limited thereto. The AP 20 is an apparatus for relaying wireless data communication. The AP 20 identifies the destination information included in the information transmitted from the transmitting side, designates an appropriate communication path to reach the receiving side, and transmits the data to the communication network corresponding to the designated communication path It is a device that can transmit. The AP 20 uses the short distance communication and transmits information such as AP identification information, SSID information, signal strength information, signal transmission time information, signal reception time information, and the like to the positioning server 30.

The AP 20 transmits and receives a wireless signal to and from the tag 10 and receives the wireless signal received from the tag 10 to check the tag information and the RSS (Recieved Signal Strength) of the received wireless signal, Adds a flag for positioning measurement to the radio signal, and transmits the radio signal to the tag (10). The AP starts time counting of the AP when transmitting the radio signal in which the flag is inserted, and terminates the time count of the AP when the radio signal into which the flag is inserted is received again from the tag 10.

The radio tag 10 receives the radio signal to which the flag is added and starts counting the time of the tag as soon as the AP 20 receives the radio signal. And, when the radio signal with the flag inserted is retransmitted back to the AP, the time count of the tag is terminated. At this time, the time count value of the tag is also transmitted to the AP. The tag 10 and the AP 20 start and end time counts independently of each other.

The AP 20 terminates the time count when the radio signal with the flag inserted from the tag 10 is re-received, and transmits the time counted value, that is, the transmission / reception time information of the radio signal including the flag, Lt; / RTI > Both the time count value of the AP and the time count value of the tag are transmitted, and at this time, the RSS information is also transmitted together. The time count value is used to calculate a time of arrival (ToA) in the positioning server. The time counting may be accomplished by clocking the AP and the tag.

The flag is an indication bit added to the ZigBee radio signal. The PPDU of the ZigBee signal is divided into a preamble (preamble), a header, and a payload (frame bit of data). A flag can be added to the payload. In more detail, the head is defined by an error encoding method, a constant amplitude varying method, a payload length, and a header check sequence in 24 bits. The payload includes a MAC header, a MAC payload and a frame check sequence. A flag bit may be added to the check sequence.

The flag may be '0' or '1', and if the flag is '1', it starts a time count for ToA calculation.

Since ZigBee is used as a communication chip, the AP normally receives and confirms only the basic information of the tag. That is, the AP receives the radio signal generated from the tag, and checks only the basic information such as the ID of the tag and the strength of the radio signal. However, if it is desired to perform positioning, the AP transmits a flag generation command to the tag, and the tag generates and transmits a radio signal with a flag added to the payload portion and receives it from the AP.

The positioning server 30 receives the RSS (Radio Frequency) information and the time information from the AP 20 and calculates the position of the tag. The positioning server 30 calculates the position of the tag 10 to the first position using the arrival time ToA information and receives the RSS of the radio signal to determine the position of the tag 10 as the second Position, and then combines them to calculate the final position.

The specific configuration and operation will be described with reference to Fig.

3 is a block diagram showing the detailed configuration of the positioning server 30. As shown in Fig.

Referring to FIG. 3, the positioning server 30 may include a wireless communication unit 32, a database 34, a parameter storage unit 38, and a positioning unit 39.

The wireless communication unit 32 communicates with the AP 20 and receives an intensity value and a time count value of the wireless signal received from the tag by the AP. The radio signal may be an e-Zigbee signal.

The database 34 previously measures and stores the strength of the radio signal and the TOA information for each position of the room to be positioned. The database 34 includes a first database 35 for storing TOA information and a second database 36 for storing the intensity of the wireless signal. The detailed configuration of the first database 35 and the second database 36 will be described later.

The parameter storage unit 38 stores various delay information generated at the time of arrival time measurement. The delay information may include a system delay of a receiving end, a system delay of a transmitting end, a loopback delay, and the like.

The positioning unit 39 receives the time information and the RSS information from the AP and compares the time information and the RSS information with the value stored in the database 34 to calculate the position of the tag 10.

4 shows a case where APs are arranged in a space of 15 m in length and 15 m in length, respectively, and a database structure therefor.

FIG. 4A shows AP arrangement and cell classification, and FIG. 4B shows ToA values in each cell.

Referring to FIG. 4, eight APs are arranged, and 25 (C1 to C25) cell regions are classified. The ToA information for each cell area is stored.

As shown in FIG. 4B, the first database 35 may store ToA values for all the APs AP1 to AP8 in the respective cell areas.

In the ZigBee chip, an error of about 37 m occurs when the bandwidth is 2 MHz, and an error of about 18 m occurs when the bandwidth is 4 MHz. In other words, when the bandwidth is 4MHd, the sampling rate becomes 16Mhz, and during the mid-clock period, the signal flows at 18.75m at 1 / 16MHz = 62.5ns. An error boundary of 9.375 m radius (R) is generated. The clock means the interval by the sampling rate.

Therefore, the AP has the same time value (ToA) within the error radius (R) from the AP, and the clock value increases by one clock when the error radius is outside the radius.

For example, in cell 1 (C1), the ToA values have the same value because they are within the error radius from AP1 and AP3. If this value is T1, the values at AP2, AP4, AP5, AP6, AP7 and AP8 are T1 + 1. Likewise, in cell 13 (C13), the values at AP3, AP4, AP5 and AP6 are 'T1' and the values at AP1, AP2, AP7 and AP8 are 'T1 + 1'.

The first database 35 stores ToA information for all APs in all defined cell areas. Since this information is stored in the first database 35 in advance, the positioning unit 39 can refer to the value of the first database 35 to know which area the tag is located in. That is, it is possible to know which of the cells 15 to 15 belong in the cell 1. The positioning unit 39 receives a plurality of AP signals AP1 to AP8, calculates a ToA value, and compares it with a first database value.

For example, when the calculated ToA value, that is, the ToA value of AP1 to AP8 is (T1 + 1, T1 + 1, T1, T1, T1, T1, T1 + Compares which region the data coinciding with the above values is. In this case, it can be seen that the tag 10 is in the cell 13 (C13) area.

When the APs are arranged in the form of FIG. 4, there is no overlapping value in the first database 35. That is, there is no overlapping value, and the position can be found at a time by the ToA comparison, but in some cases, the value stored in the database may be overlapped depending on the AP arrangement.

FIG. 5 shows an example of overlapping ToA values. FIG. 5A shows the AP arrangement and cell area, and FIG. 5B shows the ToA values stored in each cell.

Referring to FIG. 5, it can be seen that 16 APs (AP1 to AP16) are arranged in a 30-m-wide area and 100 cells (C1 to C100) are defined.

In this embodiment, the cell 3 (C3) is located within a clock distance from AP1, AP2, AP3, AP5, AP6, and AP7 and has a ToA value of 'T1', and AP4, AP9, Is located outside the clock distance and can be confirmed to have a ToA value of 'T1 + 1'.

At this time, the cell 10 (C10) located next to the cell 3 (C3) also has the same ToA value in the cell 3 (C3). That is, in the cell 3 area and the cell area 10, the same ToA value is obtained for all the APs (AP1 to AP16), and the two areas can not be distinguished by the ToA value.

Therefore, in this case, the position of the tag is determined by another method. In this embodiment, the position is determined based on the strength RSS of the wireless signal.

FIG. 6 shows an example of the second database 36. FIG.

Referring to FIG. 6, the intensity of a radio signal in each cell region is stored in a table form.

The position determination unit 39 compares the strength of the radio signal received from the AP with the value stored in the second database 36 to calculate the position.

For example, in the case of using the ToA value, since the ToA values of the cells 3 (C3) and 10 (C10) are the same, the positions can not be distinguished but the RSS values have different values. Can be distinguished.

As described above, a more accurate position can be calculated by using the ToA map, and even when the position can not be obtained because the ToA value is duplicated, it can be compensated by using the radio signal intensity value.

Hereinafter, a method of calculating ToA in the position determination unit 39 will be described in detail.

The positioning unit 39 calculates an accurate arrival time ToA based on the time count information received from the AP. TWR To (Two Way Ranging Time of Arrival) scheme can be used.

FIG. 7 shows a time counting method between an AP and a tag for calculating ToA.

First, when the tag information including the ID of the tag is transmitted in the tag (S1), the AP receives the tag information and confirms the strength of the radio signal and the tag information. The AP confirms the tag information, confirms the ID of the tag, transmits the flag generation command to the tag (S2), and starts the time counting at the same time. At this time, transmission time information is stored. Upon receipt of the flag generation command, the tag adds a flag for measurement of position to the wireless signal and transmits the flag to the AP (S3). The flag may be '1' or '0' as described above. When the radio signal to which the flag is added is received again, the AP stores the received time and ends the time counting. Using this method, it is possible to measure the ToA even if the AP only counts the clock at the AP without time synchronization between the AP and the tag. The AP can generate a flag generation command based on a control signal received from the positioning server 30. [

At this time, if the difference between the time (t0) at which the flag generation command signal is transmitted and the time (t1) at which the flag is received again is obtained at the AP, the distance to the tag can be obtained.

FIG. 8 shows a ToA measurement method between one tag and four APs.

As in FIG. 7, the tag 10 generates and propagates a radio signal, and each of the APs AP1 to AP4 receives it to check tag information and generate a flag generation command. The initial radio signal can be received by all four APs at the same time (S1), but the generation of the flag generation command and the time counting are sequentially performed (S2 to S5). That is, while the first AP 1 transmits a flag generation command to the tag 10 and receives a signal inserted with the flag " 1 " from the tag 10 (S2), the remaining APs wait, When it is finished, the second AP (AP2) transmits a flag generation command and receives a radio signal to which a flag is added (S3). In this way, even if the AP increases, the time is counted sequentially. That is, when the first AP performs communication for positioning measurement with the tag 10, the other APs do not interrupt.

The positioning server 30 receives the time value counted by the AP, and calculates the position of the tag using the time difference. However, to accurately measure the actual flight time of a radio signal, various delay factors must be considered. Between time t0 and time t1, there are several delay elements that occur in the device.

Fig. 9 shows a method of calculating a time-of-arrival value considering such a delay component. In FIG. 7, AP and tag are expressed as Node A and Node B for convenience.

The delay elements that occur from the Node A to the time point t7 when the signal is generated at the initial point t0 and then received again via the Node B are as follows.

.t0 ~ t1: TOA packet transmission delay of node A System delay in RF / Modem Tx module. T1

.t1 ~ t2: TOA packet propagation delay. T_prop

.t2 ~ t3: Delay in receiving TOA packet from node B. System delay in RF / Modem Rx module. T2

.t3 to t4: Delay in transmission of TOA packet from node B. System LoopBack delay in MCU / MODEM, T3

.t4 ~ t5: Delay in transmission of TOA packet from node B. System delay in RF / Modem Tx module. T4

.t5 to t6: TOA packet propagation delay (Propagation Delay), T_prop

.t6 to t7: Delay in receiving TOA packet from node A. System delay in RF / Modem Rx module. T5

.t0 ~ t7: Node_A The time it takes for the modem to send / receive, T6

Therefore, the actual signal transmission / reception time (T_prop) between the two nodes can be obtained as shown in Equation (1) below.

&Quot; (2) "

(T1-t0) + (t3-t2) + (t5-t4) + (t7-t6) in the above Equation 1 is expressed by the system delay T_system, Equation It is arranged together.

&Quot; (3) "

T_Prop = (T6 - T3 - T_system delay) / 2

When T_prop is obtained from Equations (2) and (3), the distance between two nodes can be calculated by multiplying the propagation speed. That is, the distance can be obtained by multiplying the propagation speed by the time value.

Since the values for the respective delay components are stored in the parameter storage unit 38, when the time value is received, the position determination unit 39 can calculate an accurate ToA value based on Equations 2 and 3 above.

When the ToA value is calculated, the position determination unit 39 compares the value with the value stored in the first database 35 to calculate the position of the tag. The value stored in the first database 35 is also a value stored in consideration of the delay factors.

As described above, the position determination unit 39 obtains the position of the tag using the ToA, and if the value stored in the database is duplicated and the position of the tag can not be specified, the position of the tag can be obtained using the RSS value have.

When the position of the tag is determined as described above, the position determining unit can calculate the final position of the tag by combining the value obtained by the strength of the radio signal and the value obtained by the arrival time.

As a method of calculating the final position, two values may be obtained by averaging them arithmetically, and in some cases, one of the values may be weighted.

If the position of the tag is calculated by combining the two values as described above, it is possible to obtain a more accurate result than when calculating the position based on the intensity of the conventional radio signal.

10 is a flowchart illustrating a positioning method according to an embodiment of the present invention.

First, the AP receives the wireless signal generated in the tag (S10) and confirms the strength of the wireless signal and the tag information. The AP that has confirmed the tag information transmits the wireless signal including the flag to the tag and starts the time counting of the AP (S11). The tag receives the radio signal to which the flag is added and starts time counting of the tag. The received wireless signal is transmitted to the AP again (S12). After transmitting the radio signal to the AP, the tag ends the time count of the tag. The AP receives the radio signal including the flag and ends the time count of the AP. The AP transmits time information including the time count value of the AP and the time count value of the tag to the positioning server together with the radio signal strength (RSS) value (S13).

The positioning server first calculates ToA using the time information (S14), and compares the calculated ToA value with the ToA stored in the first database (S15). If the comparison result shows that there is only one matching value, the cell region of the corresponding value is determined as the tag position (S16). If the comparison result shows that there is more than one value, the received RSS value is compared with the RSS value stored in the second database (S17), and the cell region having the matching value is determined as the tag position (S18).

While the invention has been shown and described with reference to certain preferred embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined by the appended claims. Accordingly, the true scope of the present invention should be determined by the following claims.

Claims (15)

delete delete A tag for generating a wireless signal;
Receiving a radio signal from the tag, checking a tag ID and strength of the received radio signal, transmitting a radio signal including a flag to the tag, receiving a radio signal including a flag from the tag, An AP for transmitting transmission / reception time information of a wireless signal including intensity information and a flag; And
And a positioning server for receiving the wireless signal strength information and the wireless signal transmission / reception time information from the AP and determining the position of the tag,
The tag starts counting time of a tag when receiving a radio signal signal including a flag from the AP and terminates a time count of the tag when transmitting the radio signal including the flag to the AP,
The AP starts a time count of the AP when the radio signal including the flag is transmitted to the tag, terminates the time count of the AP upon receiving the radio signal including the flag from the tag,
The positioning server,
A wireless communication unit for receiving transmission / reception time information and RSS (Received Signal Strength) of a radio signal including a flag from the AP;
A first database in which a measured Time of Arrival (ToA) value in a predefined area of a square of 15 m in length and 15 m is stored;
A second database in which a measured RSS value is stored in a predefined area of a square of 15 m in length and 15 m in length;
A parameter storage unit for storing delay parameters generated when wireless communication between the tag and the AP is performed; And
The wireless communication unit subtracts the delay parameter from the time information received by the wireless communication unit to calculate a ToA value with respect to APs arranged in a predefined area of a square of 15 m in length and 15 m and stores the calculated ToA values in the first database And comparing the calculated RSS value and the ToA value stored in the first database with each other to determine whether the tag value matches the ToA value, And a positioning unit for comparing the RSS values stored in the second database and determining the tag position as a matching area,
Wherein the first database stores all transmission and reception time information of the RFID tag, which is arranged in a predefined area of the square of 15 m in length and width,
The AP includes a plurality of APs in a predefined area of a square of 15 m in length and 15 m in length, each circle having a radius of 9.375 m having a radius of about 3 m And the indoor positioning device is arranged so as to be overlapped with the cell space.
The method of claim 3,
Wherein the tag is an e-Zigbee tag.
5. The indoor positioning device of claim 4, wherein the flag is added to a payload field of an e-Zigbee PPDU field.
The method of claim 3,
Wherein the tag simultaneously transmits the time count value of the tag when transmitting the radio signal including the flag to the AP.
The method according to claim 6,
Wherein the transmission / reception time of the radio signal including the flag includes a time count value of the tag and a time count value of the AP.
delete delete The method of claim 3,
A plurality of APs are arranged in an indoor space,
Wherein the plurality of APs sequentially transmit the flag generation command and the radio signal including the flag.
The tag generating a wireless signal;
The AP receives a radio signal from the tag to confirm the tag ID and the strength of the received radio signal, transmits the radio signal including the flag to the tag, receives the radio signal including the flag from the tag, Transmitting radio signal strength information and radio signal transmission / reception time information including a flag;
The positioning server receiving the radio signal strength information and radio signal transmission / reception time information including the flag from the AP and determining the position of the tag;
When the tag starts counting time of a tag when receiving a radio signal signal including a flag from the AP and terminating a time count of the tag when transmitting the radio signal including the flag to the AP;
When the AP transmits the wireless signal including the flag to the tag, starts counting time of the AP and ends the time count of the AP when receiving the wireless signal including the flag from the tag;
Receiving, by the wireless communication unit of the positioning server, transmission and reception time information and a RSS value of a radio signal including a flag from the AP;
The first database of the positioning server storing the measured ToA value in a predefined area of a square of 15 m in length and width;
A second database in which the second database of the positioning server stores RSS values measured in a predefined area of a square of 15 m length and breadth;
Storing a delay parameter generated when a wireless communication between the tag and the AP is performed; And
Wherein the position server of the positioning server calculates a ToA value with respect to APs arranged in a predefined area of a square of 15 m square by subtracting the delay parameter from the time information received by the wireless communication unit, Values and the ToA values stored in the first database are compared with each other to determine the matching region as the tag position, and if the calculated ToA value and the ToA value stored in the first database match two or more Comparing the received RSS value with an RSS value stored in the second database and determining the tag location as a matching area,
Wherein the first database stores all transmission and reception time information of the RFID tag, which is arranged in a predefined area of the square of 15 m in length and width,
The AP includes a plurality of APs in a predefined area of a square of 15 m in length and 15 m in length, each circle having a radius of 9.375 m having a radius of about 3 m Wherein the plurality of indoor units are arranged so as to overlap each other at a cell interval.
12. The method of claim 11,
Wherein the time information includes a time count of the AP and a time count value of the tag.
12. The method of claim 11,
Wherein the wireless signal is an e-Zigbee wireless signal,
Wherein the flag is added to a payload field of an e-Zigbee PPDU field.
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