KR20090002764A - Time Information Estimation Method Considering Clock Drifting Effect in Radiodetermination - Google Patents

Abstract

Disclosed is a method of estimating time information in consideration of a clock drift effect. According to the present invention, a method of estimating time information considering a clock drift effect may include: acquiring round trip time (RTT) information between a master beacon and a controller installed at a position where the clock drift is not affected; Acquiring time information on the distance between each device using one RTT information, and calculating corrected response time information on the response time of the master beacon based on the time information obtained by the time information obtaining step; Acquiring time information between the master beacon and the tag based on the corrected response time information and acquiring time information on the distance between the tag and each slave beacon based on the acquired time information between the master beacon and the tag. It includes.

Description

TAO and TDOA estimating method considering clock drifting influence of the wireless positioning

The present invention relates to a method of estimating time information considering the effect of clock drift, and more particularly, a clock capable of estimating accurate time information in consideration of the drift effect of a clock in a method of recognizing a location using a beacon signal and a tag. The present invention relates to a method for estimating time information considering the effects of drift.

General location-aware technologies include ubiquitous sensor network (RFID) or ubiquitous sensor network using short-range communication in a limited area. Wide-area position recognition technology through long distance communication using Global Positioning System has been proposed.

Detailed location recognition technology using sensor technology attaches sensors and signal generators to the object to recognize the location and specific area to perform one-way / two-way communication with the object, so that the exact location of the object when the object stays in or enters the specific area Recognize and provide a predefined service.

In the object location recognition method using RFID, when an RFID tag storing tag information including an ID as ID information and coordinate information as location information is arranged at a predetermined interval in a specific physical area requiring location recognition, an object such as a user terminal The RFID reader attached thereto sends out a signal for receiving tag information from the RFID tag. The RFID tag information is transmitted to the RFID reader according to the detection of a signal of a specific frequency or a predetermined power or more, wherein the RFID reader includes the received RFID tag information, signal strength, signal arrival time, and signal reception direction according to radio wave reception of the RFID tag. Recognize the position of the object using the object position recognition information. In this way, the object location recognizing apparatus using RFID can accurately recognize the location of the object to which the RFID reader is attached or carried.

In addition, a general method of recognizing a location of a mobile terminal transmits location information of a base station by using a beacon signal of a code division multiple access (CDMA) method and recognizes the location of the mobile terminal using a time difference. This method enables location recognition without mutual interference only by changing software.

   However, one of the factors to be considered in terms of implementation when distance recognition is a problem due to clock drift.

Clock drift information for commercial crystal oscillators shows that the units are in parts per million (ppm), which can cause significant errors in distance-aware and radiolocation techniques using time information obtained through bidirectional transmission.

사이의 클록 표류 마진이 존재할 때 주어진 시간 동안의 카운팅 정보를 나타낸 것이다. 클록 표류로 인해 같은 시간 동안 서로 다르게 카운팅되고 있음을 알 수 있으며 수식적으로 다음과 같이 표현할 수 있다. Figure 1 shows different systems operating with the same clock.

It shows the counting information for a given time when there is a clock drift margin in between. It can be seen that due to the clock drift, they are counted differently for the same time, and can be expressed as follows.

 The impact of using a low cost crystal oscillator on low cost Wireless Personal Area Networks (WPANs) leads to greater clock drift margins, which in turn will affect counting errors. Especially when the measurement time is long, the difference in counting becomes larger.

 2 shows an example of a distance-aware processing procedure through bidirectional transmission to confirm the influence of clock drift.

 In an indoor environment, the distance between the two devices is so small that they are hardly affected by clock drift. However, if the response time is long after receiving the signal from device 2, it will be affected by clock drift.

라고 하면 거리 인지 오차는 대략

가 된다. 물론 단방향 전송을 통한 거리 인지 기법은 클록 표류의 영향을 거의 받지 않는 대신 클록 옵셋에 대한 영향을 받게 된다. In the case of FIG. 2, the response time is 12 as a counter, but the time for reference counting and the time for counting device 2 may be different from each other.

Speaking of distance recognition error is approximately

Becomes Of course, distance-aware techniques via unidirectional transmission are rarely affected by clock drift, but instead by clock offsets.

 Table 1 shows an example of setting parameters for checking the influence of the clock drift. In order to check the influence of the clock drift more accurately, when the distance is recognized under the conditions shown in Table 1, it can be seen that the error of several meters is generated only by the influence of the simple clock drift.

parameter Setting value (time side) Setting value (counter side)

)Propagation time between two devices

) 30 nsec 60 samples Response time (

) 1 msec 2000000 Clock drift Device 1: +15 ppm Device 2: +30 ppm - A clock cycle 0.5 nsec -

In this case, the round trip time for bidirectional communication is 1000060 nsec, which is 2000120 on the counter side. Substituting this information into the bidirectional distance recognition equation, it is as follows.

은 디바이스 1에서 측정된 전파 전달 시간을 의미하고

는 디바이스 2의 응답시간에 대한 디바이스 1에서 측정한 응답 시간을 의미한다. 끝으로

는 클록 표류의 영향이 없는 응답 시간을 의미한다. 왜냐하면 수학식 2에서

는 모든 디바이스 동일하게 알고 있는 절대값이기 때문이다. In equation (2)

Means the propagation propagation time measured in device 1

Denotes the response time measured by the device 1 with respect to the response time of the device 2. finally

Is the response time without the influence of clock drift. Because in Equation 2

Is an absolute value that all devices are equally aware of.

In other words,

이 되며 표 1에서 제시한

와 비교하면 약 22.501 nsec의 시간 오차가 발생되며 미터로 환산할 경우 약 6.7502 m의 오차가 발생됨을 알 수 있다. In this process, the propagation propagation time calculated by device 1 is

Which is presented in Table 1

Comparing with, it can be seen that a time error of about 22.501 nsec is generated and an error of about 6.7502 m occurs when converted into meters.

 Likewise, the effects of clock drift have little effect on unidirectional distance recognition, but when obtaining time difference of arrival (TDOA) information through unidirectional transmission, the effect of clock drift is long when the time between synchronization and device transmission is long. Will receive. Of course, if the clock is locked to the reference clock and periodically synchronized, sending and receiving signals before the lock is released is less affected.

Time information estimation method according to the present invention for achieving the above object radio positioning time information in consideration of the clock drift effect to obtain accurate time information in consideration of the drift effect of the clock between each of the positioning beacons and the control unit It is an object to provide an estimation method.

In order to achieve the above object, the time information estimation method considering the clock drift effect according to the present invention includes (a) RTT (Round Trip Time) information between a master beacon and a control unit installed at a position where the clock drift is not affected. Obtaining; (b) acquiring, by the controller, time information about a distance between each device by using the RTT information obtained from the master beacon; (c) calculating corrected response time information on the response time of the master beacon based on the time information obtained by the time information obtaining step; (d) obtaining time information between the master beacon and the tag based on the corrected response time information, and between the tag and each slave beacon based on the obtained time information between the master beacon and the tag. And obtaining time information on the distance.

Preferably, the time information estimation method in consideration of the clock drift effect (e) the tag transmits the time information at the time of transmission while transmitting a signal to each positioning beacon including the master beacon and the slave beacons Storing, by the positioning beacons, initial reception time information of the received signal; (f) the master beacon retransmitting a signal after processing the corrected response time, and the tag and the remaining positioning beacons store time information about a reception point of a received signal; (g) storing the time information at the time of transmission while retransmitting the signal after a predetermined processing response time, and wherein each of the positioning beacons stores time information on the time at which the received signal is received; And (h) calculating, by the controller, the corrected response time of the tag based on the difference of the respective time information.

Here, step (h) includes (i) calculating a corrected propagation propagation time between the master beacon and the tag from information obtained through a bidirectional transmission process, wherein the corrected response of the master beacon It is desirable to calculate the corrected response time of the tag based on the time information.

In addition, obtaining time information on the distance between the tag and each slave beacon is obtained based on the calculated propagation propagation time between the master beacon and the tag and the difference of the respective time information. It is desirable to.

In the step (b), it is preferable to obtain time information on the distance between the devices based on the following equation.

Here, A represents a master beacon, and C represents a control unit.

Also, in the step (c), it is preferable to calculate corrected response time information for the response time of the master beacon by assuming that there is no drift effect of the clock operated by the controller.

Preferably, in the step (d), the respective time information obtained is as follows.

,

, 및

는 상기 태그의 신호 전송에 대하여 상기 각각의 측위용 비콘들이 저장하는 수신신호의 최초 수신 시각정보이며, 상기

,

,

, 및

는 상기 마스터 비콘의 신호 재전송에 대하여 상기 태그 및 상 기 각각의 측위용 비콘들이 저장하는 시각정보이고, 상기

,

, 및

는 상기 태그의 신호 재전송에 대하여 상기 각각의 측위용 비콘들이 저장하는 시각정보를 나타낸다.Where

,

, And

Is the initial reception time information of the received signal stored by each of the positioning beacons for the signal transmission of the tag,

,

,

, And

Is visual information stored by the tag and the positioning beacons for the signal retransmission of the master beacon,

,

, And

Denotes visual information stored by the positioning beacons for signal retransmission of the tag.

을 기준정보로 사용하여 상기

의 보정값

을 얻으며, 상기 보정값

에 기초하여 다음과 같이 상기 태그의 보정된 응답시간

을 산출한다.Preferably, the corrected response time of the master beacon

Using as reference information

Correction value

To obtain the correction value

Based on the corrected response time of the tag as follows

To calculate.

Here, the time information on the distance between the master beacon and the tag is calculated as follows.

에 기초하여 다음과 같이 보정된

을 산출한다.In addition, the corrected

Based on

To calculate.

에 상기 슬레이브 비콘의 최초 수신 시점 정 보인

를 더하여 보정된 시각정보

를 산출한다.Preferably, the corrected

Information on the initial reception time of the slave beacon

Corrected visual information by adding

Calculate

, 상기 마스터 비콘과 상기 태그 사이의 거리에 대한 시간정보, 및 상기 보정된 시각정보

에 기초하여 산출된다.In addition, time information on the distance between the tag and each slave beacon is time information on the distance between the master beacon and the slave beacon preset.

Time information about a distance between the master beacon and the tag, and the corrected visual information.

Calculated based on

Thus, the time information estimation method according to the present invention can obtain accurate time information in consideration of the drift effect of the clock between each of the positioning beacons and the control unit.

According to the present invention, in a method of recognizing a location using a beacon signal and a tag, accurate time information can be estimated in consideration of the drift effect of the clock, and accordingly, the time information estimation considering the clock drift effect according to the present invention can be estimated. The position recognizing apparatus to which the method is applied can accurately recognize the position of the tag.

Hereinafter, a method of estimating time information considering a clock drift effect according to the present invention will be described in detail with reference to the accompanying drawings.

3 is a flowchart illustrating a method of estimating time information considering a clock drift effect according to the present invention. In general, three or more fixed positioning beacons are required to estimate the position of a tag using TOA and TDOA information.

Here, since the location of the beacons requires a distance recognition accuracy of several tens of centimeters, the beacons should be installed to ensure LOS indoors, and the position of the beacons, that is, the coordinates, should be accurately measured in advance. Positioning operation structure described in the present invention will be described by configuring a master beacon, two slave beacons, and a control unit for calculating the position of the tag using the collected information. However, the number of positioning beacons is not limited to this, of course.

At this time, the position coordinates of the positioning beacons and the control unit must be accurately measured in advance, and the control unit uses a clock without the influence of the clock drift, and is installed at a position close to the master beacon to correct the influence of the clock drift used for the master beacons. It serves as a reference.

를 보정하기 위해서 마스터 비콘 A와 제어부 사이의 RTT 정보를 얻게 된다(S101). 도 4는 이에 대한 처리 과정을 나타낸다.In the present invention, it is assumed that there is no influence of the clock drift of the control unit (0 ppm), and it is assumed that all beacons can communicate with all tags in the room. At this time, the master beacon A first has an incorrect response time due to the clock drift.

In order to correct the RBE information between the master beacon A and the control unit is obtained (S101). Figure 4 shows the process for this.

는 제어부의 사전에 정해진 응답 시간으로써 수신 신호의 최초 도착 성분에 대한 시각 정보를 추정하기 위한 알고리즘 처리 및 데 이터 변/복조, 프레임 재구성 시에 필요한 시간들로 결정되기 때문에 매우 긴 시간이 요구된다. 제어부에서는 마스터 비콘 A에서 획득한 RTT 정보인

를 이용하여 수학식 3과 같이 두 디바이스 간의 거리에 대한 시간 정보를 획득할 수 있다(S103). Where processing response time

Since a predetermined response time of the controller is determined by algorithm processing for estimating time information on the first arrival component of the received signal, and the time required for data modulation / demodulation and frame reconstruction, a very long time is required. The control unit is the RTT information obtained from the master beacon A

By using Equation 3, time information about a distance between two devices may be obtained (S103).

는 마스터 비콘 A의 클록 표류를 나타낸다. 고정된 두 디바이스간의 거리에 대한 시간

정보는 사전에 알고 있고 두 디바이스간의 거리가 짧기 때문에 거리에 따른 클록 표류의 영향은 거의 없다. 또한, 제어부에서 동작되는 클록의 표류 영향이 없다고 가정하면 마스터 비콘 A의 응답 시간

에 대한 다음과 같은 대략적인 보정된 정보를 얻을 수 있다(S105). here

Represents the clock drift of the master beacon A. Time for distance between two fixed devices

Because the information is known in advance and the distance between the two devices is short, there is little effect of clock drift over distance. In addition, the response time of the master beacon A assuming that there is no drift effect of the clock operated in the controller

The following roughly corrected information can be obtained (S105).

을 카운터

로 계산하면 다음과 같다. For example, corrected response time under the conditions shown in Table 2

Counter

Calculated as

의 카운터 값과 차이가 있음을 알 수 있으나 실제로 시간상으로는 거의 비슷하다. 도 5는 표 2의 조건하에서 응답시간에 대한 마스터 비콘 A의 클록 표류 영향을 보정한 카운터 결과를 나타낸 도면이다. 따라서, 마스터 비콘 A는 1999980번 카운팅한 후에 신호를 전송하게 된다.Looking at the results from Equation 5, we can see that the response time

We can see that there is a difference from the counter value of, but it is almost the same in time. FIG. 5 is a diagram showing a counter result of correcting a clock drift effect of the master beacon A on the response time under the conditions shown in Table 2. FIG. Therefore, the master beacon A transmits a signal after counting 1999980 times.

를 이용하여 태그의 위치를 추정하기 위해 요구되는 TOA, TDOA 정보를 획득하기 위한 처리 과정을 나타낸다. 6 is response time information obtained through communication between the control unit and the master beacon in advance

Represents a process for obtaining TOA and TDOA information required for estimating the position of a tag using.

를 저장하고 모든 측위 용 비콘들은 수신 신호의 최초 수신 시각 정보

,

,

를 저장하게 된다(S107). 이때, 마스터 비콘 A는 사전 보정된 처리 응답 시간

후에 신호를 재전송하게 되고 마찬가지로 태그 및 나머지 측위 용 비콘들은 수신 신호의 수신 시점에 대한 시각 정보

,

,

,

를 저장하게 된다(S109). In order to estimate the distance between the tag and the master beacon A, the tag first transmits a signal to all positioning beacons, providing visual information at the time of transmission.

Store all beacons for the first received time of the received signal

,

,

It will be stored (S107). At this time, the master beacon A is a pre-corrected processing response time

The signal will be retransmitted later, and the tag and other positioning beacons will be visually informed about when the received signal was received.

,

,

,

It will be stored (S109).

후에 다시 한번 신호를 전송하면서 전송 시점의 시각 정보

를 저장하고, 모든 측위 용 비콘들은 이를 수신하며 이때의 수신 시점에 대한 시각 정보

,

,

를 저장하게 되고(S111), 최종적으로 획득한 정보들은 제어부에 보내지며 수학식 6 내지 수학식 13과 같은 시간 정보들을 획득하게 된다. 그러나 이러한 정보들은 모두 클럭 표류 영향으로 인해 부정확한 결과이며 정확한 TOA 정보를 추정하게 위해서는 보정 과정이 필요하다.Finally, the tag has a predetermined processing response time

Time information at the time of transmission while transmitting the signal again later

To store all beacons for location and receive visual information

,

,

(S111), and finally obtained information is sent to the control unit to obtain the time information, such as the equation (6) to (13). However, all of this information is inaccurate due to clock drift effects, and a corrective process is required to estimate accurate TOA information.

을 계산한다(S113). 여기서, 수학식 10과 수학식 11로부터 얻은 결과들은 마 스터 비콘 A에 대한 클록 표류의 영향 및 태그의 클록 표류 영향이 포함되어 부정확한 결과를 나타낸다. First, the control unit corrects propagation propagation time between the master beacon A and the tag from information obtained through two double two way processes as shown in FIG. 7.

To calculate (S113). Here, the results obtained from the equations (10) and (11) include the effects of clock drift on the master beacon A and the clock drift effect of the tag, thereby showing inaccurate results.

을 기준 정보로 사용하여 비례식을 통해 수학식 7로부터 얻은

의 보정값을 얻을 수 있다. 또한, 보정된

를 기준 정보로 사용하여 태그의 보정된 응답 시간

을 계산한다(S115).However, calibrated response time of Master Beacon A

Obtained from Equation 7 through proportional expression using

The correction value can be obtained. Also, calibrated

Calibrated response time for tags using

To calculate (S115).

을 빼면 태그와 마스터 비콘 A 사이의 RTT 정보인

를 얻을 수 있으며, 다음과 같은 수학식 16으로부터 수학식 17과 같은 마스터 비콘 A와 태그 사이의 거리에 대한 시간 정보를 얻을 수 있다(S117). Here, the response time corrected from the modified information obtained from Equation 14

Minus the RTT information between the tag and master beacon A

It is possible to obtain the time information on the distance between the master beacon A and the tag as shown in Equation 17 from the following equation (16) (S117).

For example, if the corrected time information on the distance between the master beacon A and the tag under the conditions shown in Table 3 is calculated as follows.

"는 시간을 클록으로 나누고 정수형으로 바꾼 카운터를 나타내고, 이러한 변환과정에 약간의 오차가 발생될 수 있다. here "

Represents a counter that divides the time into clocks and converts them to integers, which can introduce some error.

The calculated results are derived from the assumption that the time information at the first reception time is accurate, and it can be seen that the counting value for the distance between two devices given in Table 3 and the result obtained in Equation 22 are the same. Finally, multiplying the number of counts by one clock cycle calculates the propagation time, and multiplying it by the propagation speed yields the distance information between the tag and the master beacon A.

는 도 8에 나타 낸 바와 같이, 마스터 비콘 A와 B 사이의 상이한 클록 표류의 영향으로 부정확하다. 이러한 부정확한 정보를 보정하기 위해서 수학식 14로부터 얻은 보정된 정보

와 수학식 8의 결과와의 비를 통해 보정된

를 얻을 수 있다. 물론,

는 보정된 정보이기 때문에 오차가 존재할 수 있으며 이를 통한 보정된

또한 오차가 가중될 수 있다. 도 8은 이러한 마스터 비콘 A와 슬레이브 비콘 B 사이의 TOA를 얻기 위한 처리 과정을 나타낸 도면이다.In addition, a process for obtaining propagation arrival time information between the tag and the slave beacon B is as follows. First, the reception information stored in the slave beacon B

8 is inaccurate due to the influence of different clock drifts between master beacons A and B, as shown in FIG. Corrected information obtained from Equation 14 to correct this incorrect information

Corrected by the ratio of

Can be obtained. sure,

Since is corrected information, an error may exist and the corrected information

Errors can also be weighted. 8 is a diagram illustrating a process for obtaining a TOA between the master beacon A and the slave beacon B. FIG.

를 더함으로써 보정된 다음과 같은 시각정보

를 얻을 수 있다. The result obtained from Equation 24 and the initial reception time information of the slave beacon B

Visual information corrected by adding

Can be obtained.

, 수학식 17 및 수학식 25에서 얻은 결과들을 토대로 다음과 같은 태그와 슬레이브 비콘 B 사이의 거리에 대한 시간 정보를 얻을 수 있다. Time information about the distance between master beacon A and slave beacon B, finally known beforehand

Based on the results obtained in Equations 17 and 25, time information on the distance between the following tag and the slave beacon B can be obtained.

는 사전 정의된 응답 시간을 나타낸다. 이를 증명하기 위해서 표 4와 같은 조건일 때 마스터 비콘 A와 슬레이브 비콘 B 사이의 거리에 대한 보정된 시간 정보를 계산하면 다음과 같다. here,

Represents a predefined response time. To prove this, the corrected time information on the distance between the master beacon A and the slave beacon B under the conditions shown in Table 4 is calculated as follows.

는 다음과 같이 계산될 수 있다. First obtained through Equation 12

Can be calculated as follows.

를 보정하기 위해서 앞서 설명한 방법과 동일하게 적용된다. 수학식 14로부터 얻은 보정된 정보

를 기준하여 비례식을 통해 보정된

를 얻을 수 있다.Here, it can be seen that the counting number 120 and the result obtained in Equation 30 for the distance between the master beacon A and the slave beacon B given in Table 4 are the same. Similarly, the received information stored in slave beacon C

In the same manner as described above to correct the. Corrected Information Obtained from Equation 14

Corrected by proportional expression

Can be obtained.

를 더함으로써 보정된 시각 정보

를 얻을 수 있다.In addition, the result obtained from Equation 21 and the first reception time information of the slave beacon B

Visual information corrected by adding

Can be obtained.

, 수학식 17 및 수학식 32에서 얻은 결과들을 토대로 태그와 슬레이브 비콘 C 사이의 거리에 대한 시간 정보를 얻을 수 있다. Time information about the distance between master beacon A and slave beacon C.

Based on the results obtained in Equations 17 and 32, time information on the distance between the tag and the slave beacon C can be obtained.

In addition, if the difference of each TOA information is obtained from equations (17), (26) and (33), TDOA information such as equations (34) and (35) can be obtained, and the position of the tag is estimated using this information.

Finally, the position of the tag can be calculated by applying the obtained TOA / TDOA information to the radio location algorithm. Table 5 compares the active and passive TDOA acquisition methods with the proposed TOA / TDOA acquisition methods.

parameter Existing Information Acquisition Method (Active Type) Existing Information Acquisition Method (Manual Type) Proposed Information Acquisition Method Distance awareness OWR OWR TWR Distance Awareness and Positioning Performance in Harsh GDOP Situations Not good Not good good Send / Receive Count 5 5 8 Required function of the tag Tx Rx Tx / Rx Information available for wireless positioning TDOA TDOA TOA / TDOA

As shown in Table 5, the proposed information acquisition scheme is slightly more expensive because the tag has to transmit / receive, and it has more drawbacks than other schemes, but it can use both TOA / TDOA information. Even in poor GDOP situations, the distance recognition and positioning errors are smaller than other methods. In addition, in terms of power consumption, the existing schemes have to be synchronized periodically, so that more power consumption is expected.

To verify the performance of the TOA / TDOA information acquisition scheme considering the proposed clock drift, the simulation parameters are set as shown in Table 6.

로 설정하였다. 또한 양방향 전송을 통한 거리 인지 시 요구되는 응답 시간은 0.78 ms로 하였고 측위용 비콘들의 클록 표류는 표 6과 같이 고정하였고 태그는

에서 랜덤하게 발생시켰다. 또한, 가장 단순한 방법인 세 번의 TWR을 통한 TOA 추정 방안과 Active 태그의 OWR 기반의 TDOA 추정 방안을 제안된 방식과의 비교대상으로 선정하였다. By default, one period of the applied clock is set to 0.78 ns and the TOA estimation error is

Set to. In addition, the response time required for distance recognition through bidirectional transmission was 0.78 ms, and the clock drift of positioning beacons was fixed as shown in Table 6, and the tag was

Randomly generated at In addition, the simplest method, TOA estimation method through three TWRs and OWR-based TDOA estimation method of Active tag, was selected for comparison with the proposed method.

-"PROP" = proposed TOA / TDOA estimation method

-"CONV 1" = TOA estimation method through three TWRs

-"CONV 2" = OWR-based TDOA Estimation Method of Active Tag

는 OWR 방식의 TDOA 추정 과정에서 동기화 후 태그가 전송할 때까지 걸리는 시간을 의미한다. 도 9는 시뮬레이션을 위한 각 디바이스의 위치 설정을 나타낸다. 공정한 시뮬레이션을 위한 태그의 위치는 균일 간격으로 설정하였다. Presented in Table 6

In the TWRA estimation process of the OWR method, it means the time taken until the tag is transmitted after synchronization. 9 shows the positioning of each device for the simulation. Tag positions for fair simulation were set at uniform intervals.

10 to 12 show the result of converting the TOA error according to the presence or absence of clock drift correction between the beacon and the tag when the response time is set to 0.78 ms in TWR. As shown in the figure, it can be seen that an error of up to 7 m occurs when the clock drift is not corrected. In the proposed method, the error of the first TOA was somewhat cumulative for acquiring two different TOA information. It can be seen that the effects of drift are greatly reduced.

가 1 ns일 때의 성능 결과로 제안된 방식과 거의 비슷하지만, 도 13(b)와 같이

가 0.1 ms 일 경우 TOA 오차가 증가됨을 알 수 있다. 물론 "CONV 2"는 TDOA 정보만을 얻을 수 있으나 시뮬레이션 상에서 계산을 통해 TOA 정보를 얻었다.13 shows the RMSE results for the TOA error of each technique. FIG. 13 (a) shows the time from synchronization to transmission after " CONV 2 "

Is almost similar to the proposed method as a result of the performance at 1 ns, but as shown in FIG.

It can be seen that the TOA error is increased when is 0.1 ms. Of course, "CONV 2" can only obtain the TDOA information, but obtained TOA information through the calculation in the simulation.

14 and 15 show TDOA results for each technique under the same conditions as in FIG. 13. The "CONV 2" technique also shows that the TDOA error can be weighted due to the effects of clock drift. Of course, if there is little clock drift in the synchronization process, the controller transmits a synchronization signal, and all beacons are locked periodically by a few milliseconds through a phase-locked loop (PLL), while the tag transmits a signal between them. Will be less affected.

변화에 따른 "CONV 2" 기법에 대한 측위 성능 결과를 나타낸다. 도 16에서

가 1 ms 일 경우 측위 오차는 클록 표류 영향을 고려하지 않으면 거의 측위가 되지 않으며

가 0.1 ms 에서도 제안된 기법과 비교했을 때 성능 열화가 있음을 알 수 있다. 16 is

Results of positioning performance for the "CONV 2" technique according to the change are shown. In Figure 16

Is 1 ms, the positioning error is hardly measured without considering the clock drift effect.

Shows a performance degradation even at 0.1 ms compared with the proposed technique.

17 is a comparison of the positioning performance for each technique according to the change in the distance perception error. As shown in FIG. 17, in the time information estimation method considering the clock drift effect according to the present invention, since the accumulation of the TOA error is increased when the distance recognition error is large, the difference in the performance result of other methods is slightly reduced. However, it can be seen that the performance is still improved compared to other systems.

18 shows the location performance results for each technique according to the change in response time. The "CONV 2" technique produces almost constant results because there is no response time because of the OWR scheme, while the "CONV 1" technique increases the positioning error when the response time is about 1 ms or more due to the clock drift on the response time. It can be seen.

Although the preferred embodiments of the present invention have been illustrated and described above, the present invention is not limited to the specific embodiments described above, and the present invention is not limited to the specific embodiments of the present invention without departing from the spirit of the present invention as claimed in the claims. Anyone skilled in the art can make various modifications, as well as such modifications are within the scope of the claims.

1 illustrates counting results due to different clock drifts;

2 shows an example of the influence of clock drift through a distance recognition procedure;

3 is a flowchart illustrating a method of estimating time information considering a clock drift effect according to the present invention;

4 is a diagram illustrating a process for obtaining RTT information between a master beacon and a controller;

4 is a diagram illustrating a clock drift correction process of a master beacon with respect to a response time;

5 shows the result after clock drift correction with respect to response time;

6 illustrates a process for obtaining TOA (Time of Arrival) and TDOA (Time Difference of Arrival) information required for estimating the position of a tag using response time information obtained through communication between the control unit and the master beacon. drawing,

7 is a diagram illustrating a process for obtaining a TOA between a master beacon and a tag;

8 is a diagram illustrating a process for obtaining a TOA between a master beacon and a slave beacon;

9 is a view showing the location of each device for the simulation,

10 is a view comparing the results according to the presence of the clock drift correction between the master beacon and the tag,

11 is a view comparing the results according to the presence of the clock drift correction between the slave beacon and the tag,

12 is a view comparing the results according to whether there is a clock drift correction between other slave beacons and tags;

FIG. 13 is a diagram illustrating root mean square error (RMS) results for TOA errors of respective techniques; FIG.

14 shows the RMSE result (Tc = 1 ns) for the TDOA error of each technique;

15 shows the RMSE result (Tc = 0.1 ms) for the TDOA error of each technique,

16 is a view showing a positioning performance results according to Tc change,

17 is a diagram showing the positioning performance results for each technique according to the change in distance cognition error; and

18 is a diagram showing the positioning performance results for each technique according to the change in response time.

Claims (12)

(a) obtaining, by the master beacon, Round Trip Time (RTT) information between the control unit and the control unit installed at a position not affected by clock drift; (b) acquiring, by the controller, time information about a distance between each device by using the RTT information obtained from the master beacon; (c) calculating corrected response time information on the response time of the master beacon based on the time information obtained by the time information obtaining step; (d) obtaining time information between the master beacon and the tag based on the corrected response time information, and between the tag and each slave beacon based on the obtained time information between the master beacon and the tag. A method of estimating radio positioning time information in consideration of clock drift effects, comprising the step of obtaining time information on a distance. The method of claim 1, (e) the tag transmits a signal to each of the positioning beacons including the master beacon and the slave beacon, and stores time information at the time of transmission, wherein each of the positioning beacons is the first received time information of the received signal. Storing the; (f) the master beacon retransmitting a signal after processing the corrected response time, and the tag and the remaining positioning beacons store time information about a reception point of a received signal; (g) storing the time information at the time of transmission while retransmitting the signal after a predetermined processing response time, and wherein each of the positioning beacons stores time information on the time at which the received signal is received; And and (h) calculating, by the controller, a corrected response time of the tag based on the difference of the respective time information. The method of claim 2, wherein (h) comprises: (i) calculating a corrected propagation propagation time between the master beacon and the tag from the information obtained through a bidirectional transmission process, And calculating the corrected response time of the tag based on the corrected response time information of the master beacon. The method of claim 3, wherein Acquiring time information on the distance between the tag and each slave beacon is obtained based on the calculated propagation propagation time between the master beacon and the tag and the difference of the respective time information. Radio positioning time information estimation method considering the clock drift effect. The method of claim 1, Step (b) is a radio positioning time information estimation method in consideration of the clock drift effect, characterized in that to obtain the time information on the distance between each device based on the following equation:

Here, A is a master beacon, C is a control unit. The method of claim 5, In step (c), assuming that there is no drift effect of the clock operated by the controller, the corrected response time information for the response time of the master beacon is calculated by the following equation. Radio positioning time information estimation method:

The method of claim 2, In the step (d), each time information obtained is as follows: radio positioning time information estimation method considering the clock drift effect, characterized in that:

Where

,

, And

Is the initial reception time information of the received signal stored by each of the positioning beacons for the signal transmission of the tag,

,

,

, And

Is visual information stored by the tag and the respective positioning beacons for signal retransmission of the master beacon,

,

, And

Represents visual information stored by each of the positioning beacons for signal retransmission of the tag. The method of claim 7, wherein Corrected response time of the master beacon

Using as reference information

Correction value

To obtain the correction value

Based on the corrected response time of the tag as follows

Radio positioning time information estimation method considering clock drift effect, comprising:

The method of claim 8, Time information for the transaction between the master beacon and the tag is calculated as follows: radio positioning time information estimation method considering the clock drift effect:

The method of claim 8, Corrected above

Based on

Radio positioning time information estimation method considering clock drift effect, comprising:

The method of claim 10, Corrected above

Is the first reception time information of the slave beacon

Corrected visual information by adding

Radio positioning time information estimation method considering the clock drift effect, characterized in that to calculate the. The method of claim 11, Time information on the distance between the tag and each slave beacon is time information on the distance between the preset master beacon and the slave beacons

Time information on the distance between the master beacon and the tag, and the corrected time information.

Radio positioning time information estimation method considering the clock drift effect, characterized in that calculated based on.

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