KR101289597B1 - Apparatus and method for estimating location of an optical source by circular pd array - Google Patents

Abstract

In the present specification, a method for estimating the position of a light source in a wireless access system, comprising: receiving an optical signal from the light source through a circular array, wherein the circular array includes at least one photo detector (PD); ); Calculating the power received at each photodetector of the circular array; Determining a first photodetector and a second photodetector in the circular array by using the received power of each photodetector, the first photodetector being a photodetector having a maximum received power, and the second photodetector being the Photodetectors positioned on both sides of the first photodetector; And estimating the position of the light source using the determined received power of the first photodetector and the second photodetector.

Description

A method and apparatus for estimating the position of a light source using a circular PD array {APPARATUS AND METHOD FOR ESTIMATING LOCATION OF AN OPTICAL SOURCE BY CIRCULAR PD ARRAY}

TECHNICAL FIELD This disclosure relates to a position estimation system, and more particularly, to a method and apparatus for estimating the position of a light source using a circular PD array.

As one of the eco-friendly fields, LED is becoming an issue. LEDs are emerging as eco-friendly, with higher efficiency, longer life, different applications and mercury-free than other light sources. Therefore, the trend of using a lot of LED not only in Korea but also in many countries around the world.

In particular, in the field of environment, the Kyoto Protocol, WEEE (Waste Electrical and Electronic Equipment), and international agreements have strengthened the regulation of carbon emissions due to the low carbon policy and green growth, which led to the need for LEDs. In Korea, the government is conducting a 1530 project (a project that changes 30% of the nation's lighting into LEDs by 2015).

There are many applications using LED, among which there is a method of estimating the location using LED. Location estimation using LEDs can be largely divided into indoor and outdoor.

In the interior, large buildings (multiple shopping malls, department stores, large discount marts) are being built. Unlike the old days, life in the indoors is increasing, and spending a day in a large complex shopping mall is a culture for modern people. to be.

As people spend more time in large buildings, they need to estimate their location indoors. Conventional position estimation is a position estimation using GPS. The position estimation is possible for the horizontal and vertical positions, but the height is not estimated. In addition, new location estimation using Wi-Fi has emerged, and this method has a problem in that a lot of Wi-Fi zones need to be installed.

In addition, even if a lot of Wi-Fi is installed, there is an error, while a slight error of the horizontal and vertical is allowable, while the error of the height is not acceptable because the error of the height represents the error between one floor. So if you change the light to LED in a large shopping mall, you don't need to install a base station similar to the one that requires separate Wi-Fi zones, and there is no error between floors. This is necessary.

In addition, there is a need for methods for estimating the position of vehicles on the road outdoors. Many accidents are caused by changing lanes, one of the most common types of traffic accidents, and by not having a safe distance between the front and rear cars. It causes an accident because the position between the front car and the rear car is not known. Thus, the position estimation between vehicles is needed. In the case of the WAVE used for the next-generation vehicle communication, a device for generating a signal must be newly installed in the vehicle, but a device for generating a separate signal is unnecessary for the position estimation method using the headlamp.

The present specification is to solve the above problems, to provide a method for estimating the position of the light source using the received power in each PD located in the circular PD array (circular-PD-array).

In the present specification, a method for estimating the position of a light source in a wireless access system, comprising: receiving an optical signal from the light source through a circular array, wherein the circular array includes at least one photo detector (PD); ); Calculating the power received at each photodetector of the circular array; Determining a first photodetector and a second photodetector in the circular array by using the received power of each photodetector, the first photodetector being a photodetector having a maximum received power, and the second photodetector being the Photodetectors positioned on both sides of the first photodetector; And estimating the position of the light source using the determined received power of the first photodetector and the second photodetector.

)로 표현되는 것을 특징으로 한다.In addition, the position of the at least one photo detector is a position on the circular array according to the following equation (

). ≪ / RTI >

In addition, the power received by each photo detector is characterized in that calculated according to the following equation.

In addition, the position of the light source is characterized in that estimated according to the following equation.

Also, the present specification provides a method for estimating the position of a light source in a wireless access system, the method comprising: receiving an optical signal of the light source through a first circular PD array and a second circular PD array, the first circular array and the The second circular array consists of at least one photo detector (PD); Calculating power received at each photodetector of the first circular array and the second circular array; Determining a first photodetector and a second photodetector in each of the first circular array and the second circular array using the received power of each photodetector, wherein the first photodetector has a maximum received power Wherein the second photodetector is a photodetector positioned at both sides of the first photodetector; And estimating the position of the light source using the received powers of the first photodetector and the second photodetector respectively determined in the first circular array and the second circular array.

In addition, estimating the position of the light source may include calculating an angle at which the received optical signal is incident to the first circular array and the second circular array; Measuring a distance between the first circular array and the second circular array; And estimating the position of the light source using the calculated angle and the measured distance using a triangulation method.

In addition, an optical receiver for estimating the position of the light source, comprising: an optical receiver for receiving an optical signal from the light source; And a control unit connected to the light receiving unit, wherein the light receiving unit includes a circular array including at least one photo detector (PD), wherein the control unit is received at each photo detector of the circular array. Calculates power, determines a first photodetector and a second photodetector in the circular array using the received power of each photodetector, and uses the determined received power of the first photodetector and the second photodetector. The first photo detector is a photo detector having a maximum received power, and the second photo detector is a photo detector positioned at both sides of the first photo detector.

)로 표현되는 것을 특징으로 한다.In addition, the position of the at least one photo detector is a position on the circular array according to the following equation (

). ≪ / RTI >

Here, R represents the radius of the circular PD array, K represents the number of PDs, i is the index of the PD, i = 1, 2, ..., K.

In addition, the power received by each photo detector is characterized in that calculated according to the following equation.

Here, P _t represents the transmission power of the light source, H _i (0) represents the channel DC gain between the light source and the optical receiver, and N (i) represents noise.

 In addition, the position of the light source is characterized in that estimated according to the following equation.

를 나타내며,

을 나타내며, C_m은 가중치 계수(weighting coefficient)를 나타낸다.here,

Lt; / RTI >

C _m represents a weighting coefficient.

In this specification, by using the received power in the PD of the circular PD array, there is an effect that can reduce the error for the position estimation of the light source.

In addition, the present specification hardly generates errors between floors indoors in estimating the position of the light source (indoor navigation effect), and does not need to separately install a device for generating an optical signal indoors and outdoors (indoor lighting, etc.). , The vehicle can be estimated by the lighting device) has the effect of reducing the cost.

1 (a) and (b) are conceptual diagrams illustrating an optical communication system to which an embodiment of the present specification can be applied.
2 is a flowchart illustrating a light source position estimation method according to an exemplary embodiment of the present specification.
Figure 3 (a) and (b) is a diagram showing the LED sensitivity (sensitivity) and PD sensitivity, respectively.
4 illustrates a circular PD array according to an embodiment of the present specification.
FIG. 5 is a diagram illustrating PDs having a maximum received power and PDs adjacent to PDs having a maximum received power according to an embodiment of the present disclosure.
6 is a diagram illustrating estimating a position of a front or rear vehicle using a light source position estimation method according to an embodiment of the present disclosure.
7 (a) to (c) are diagrams illustrating a position estimation error of a light source according to the number of PDs when the DOA algorithm proposed in the present specification is applied.
8 is a diagram illustrating an internal block diagram of an optical transmitter and an optical receiver to which an embodiment of the present disclosure can be applied.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings, wherein like reference numerals refer to like or similar elements throughout the several views, and redundant description thereof will be omitted. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail. It is to be noted that the accompanying drawings are only for the understanding of the present invention and should not be construed as limiting the scope of the present invention. The spirit of the present invention should be construed as extending to all modifications, equivalents, and alternatives in addition to the appended drawings.

Hereinafter, a method of estimating the position of a light source (or an optical transmitter) using the circular PD array proposed in the present specification, that is, a DOA algorithm, will be described in detail.

1 (a) and (b) are conceptual diagrams illustrating an optical communication system to which an embodiment of the present specification can be applied.

The optical communication system 100 includes an optical transmitter (or a light source 110) and an optical receiver 120.

First, the optical transmitter 110 transmits data using light (eg, visible light).

Here, the light transmitting apparatus 110, that is, the light source may use an LED. For example, the light transmitting apparatus 110 may be an indoor fluorescent lamp, an automobile head lamp, a street lamp using an LED.

In addition, the optical transmitter 110 modulates data through any one of various modulation schemes, and then transmits the modulated signal using light through a wavelength band suitable for the characteristics of the modulated signal.

The optical receiver 120 receives data transmitted from the outside (the optical transmitter or the light source). In addition, the optical receiver 120 may be a circular PD array, as shown in Figure 1 (b).

Here, the optical transmission device and the optical reception device may be in the form of a small sensor such as a tag, a mobile terminal such as a mobile phone, a PDA, a fixed terminal in the form of a desktop, or may be included in a vehicle.

In addition, the optical transmitter and / or the optical receiver can be used more efficiently in combination with a communication system using other communication media of wired and wireless communication.

2 is a flowchart illustrating a light source position estimation method according to an exemplary embodiment of the present specification.

Referring to FIG. 2, the optical receiver receives an optical signal transmitted from a light source (or an external optical transmitter) using a circular PD array (S210).

 The circular PD array may include at least one photo detector (PD) or photo diode (PD). Hereinafter, for convenience of description, the photodetector or photodiode is referred to as 'PD'.

The at least one PD is disposed on the circular PD array at regular intervals.

)로 표현될 수 있다.That is, the position of the at least one PD is determined by the position on the circular PD array according to Equation 1 below.

Can be expressed as

Where R denotes the radius of the circular PD array, K denotes the number of PDs, and i denotes the index of the PD. (I = 1, 2, ..., K)

For example, for a first PD (left or right) on a circular PD array, i = 1, for a second PD, i = 2... .

Thereafter, the optical receiver calculates power received at each PD of the circular PD array (S220). Received power in each PD may be expressed as Equation 2 below.

Here, P _t represents the transmission power of the light source, H _i (0) represents the channel DC gain between the light source and the optical receiver, and N (i) represents noise.

In addition, H (0), that is, the channel DC gain may be obtained according to Equation 3 below.

는 광신호의 광 수신장치로의 입사(incidence)각을 나타내며,

는 광도(irradiance)각을 나타내며,

는 광 필터의 이득을 나타내며,

는 광 집중기(concentrator)의 이득을 나타내며,

는 수신기에서 시야폭(width of the field of vision)을 나타낸다.Here, A represents the physical area of the detector in the PD, D _d represents the distance between the light source (or transmitter) and the optical receiver (or receiver),

Denotes the angle of incidence of the optical signal into the optical receiver,

Represents the angle of irradiance,

Represents the gain of the optical filter,

Represents the gain of the light concentrator,

Denotes the width of the field of vision at the receiver.

는 하기 수학식 4와 같이 표현할 수 있다.Here,

Can be expressed as Equation 4 below.

Here, n represents a refractive index.

및

는 각각 LED 민감도(sensitivity)(도 3 (a)) 및 PD 민감도(도 3 (b))를 나타낸다.In Equation (4)

And

Denotes LED sensitivity (FIG. 3 (a)) and PD sensitivity (FIG. 3 (b)), respectively.

That is, FIGS. 3A and 3B are diagrams illustrating LED sensitivity and PD sensitivity, respectively.

In Equation 2, noise N (i) is composed of shot noise, thermal noise, and intersymbol interference due to optical path difference. That is, the noise N (i) may be expressed as Equation 5 below.

는 하기 수학식 6과 같이 표현될 수 있다.here,

May be expressed as in Equation 6 below.

및

는 각각 하기 수학식 7 및 수학식 8과 같이 표현될 수 있다.Also,

And

May be represented by Equations 7 and 8, respectively.

은 신호 전력을 나타내며,

는 인접 심볼 간 간섭으로 인한 수신 전력을 나타내며, B는 동일한 잡음 대역폭(equivalent noise bandwidth)을 나타내며,

는 백그라운드 전류(background current)를 나타낸다.Where q represents electric charge,

Represents signal power,

Denotes the received power due to interference between adjacent symbols, B denotes the equivalent noise bandwidth,

Denotes a background current.

Here, the first part and the second part of Equation 8 represent feedback resistor noise and FET channel noise, respectively.

는 단위 영역 당 PD의 고정 커패시턴스(capacitance)를,

는 FET 채널 잡음 요소를, g_m는 상호 컨덕턴스(transconductance)를 나타낸다.In addition, K is the Boltzmann constant, T _k is the absolute temperature, G is the open-loop voltage gain,

Is the fixed capacitance of the PD per unit area,

Is the FET channel noise component and g _m is the transconductance.

Thereafter, the optical receiver determines the first photodetector and the second photodetector in the circular PD array by using the received power of each photodetector (S230).

Here, the first photodetector is a photodetector having a maximum reception power among the photodetectors of the circular PD array, and the second photodetector is photodetectors positioned at both sides of the first photodetector. Here, the photodetector positioned in the same or closest direction to the direction in which the optical signal is transmitted from the light source may have the maximum received power among the photodetectors on the circular PD array.

Thereafter, the optical receiving apparatus estimates the position of the light source through the truncated-weighting method using the determined reception powers of the first photodetector and the second photodetector (S240).

That is, a method of estimating the position of the light source by the optical receiver using the above method is called a 'direction of arrival (DOA) algorithm'.

Here, the truncated-weighting scheme may be expressed by Equation 9 below.

를 나타내며,

을 나타낸다.here,

Lt; / RTI >

.

In addition, C _m represents a weighting coefficient and may be expressed as in Equation 10 below.

As another example, the optical receiver may more accurately estimate the position of the light source by using a plurality of circular PD arrays.

, 광원 및 제 2 원형 PD 어레이 간의 추정각

를 산출한다.For example, when the optical receiver estimates the position of the light source through two circular PD arrays, the optical receiver estimates an angle between the light source (or the optical transmitter) and the first circular PD array.

, Estimated angle between light source and second circular PD array

.

The optical receiver then measures the distance between the first circular PD array and the second circular PD array.

및

와, 상기 측정된 제 1 원형 PD 어레이 및 제 2 원형 PD 어레이 간의 거리를 이용하여 광원의 위치를 추정한다. 여기서, 광 수신장치는 삼각 측량 방식을 이용하여 광원의 위치를 추정한다.
Then, the optical receiving apparatus calculates the estimated angle

And

And estimate the position of the light source by using the measured distance between the first circular PD array and the second circular PD array. Here, the optical receiver estimates the position of the light source using a triangulation method.

4 illustrates a circular PD array according to an embodiment of the present specification.

As shown in FIG. 4, it can be seen that 9 PDs are located on a circular PD array (401-409). The nine PDs are located on a circular PD array according to Equation 1 above.

Here, each of the PDs on the circular PD array may receive the maximum power when receiving the optical signal transmitted in the direction corresponding to the position of each PD.

FIG. 5 is a diagram illustrating PDs having a maximum received power and PDs adjacent to PDs having a maximum received power according to an embodiment of the present disclosure.

Referring to FIG. 5, a PD 510 positioned in a direction coinciding with a direction of an optical signal transmitted from a light source receives maximum power (first photodetector), and photos located adjacent to the first photodetector. Two detectors 520 and 530 correspond to the second photo detector.

6 is a diagram illustrating estimating a position of a front or rear vehicle using a light source position estimation method according to an embodiment of the present disclosure.

Referring to FIG. 6, vehicle 1 610 having two circular PD arrays 611 receives an optical signal transmitted from vehicle 2 620 in each of the two circular PD arrays 611 and receives vehicle 1 ( 610 estimates the position of vehicle 2 620 by applying the above-described DOA algorithm. Here, the two circular PD arrays 611 provided in the vehicle 1 may be located on the left side and the right side of the vehicle 1, respectively.

7 (a) to (c) are diagrams illustrating a position estimation error of a light source according to the number of PDs when the DOA algorithm proposed in the present specification is applied.

FIG. 7A illustrates a case where 9 PDs are located in a circular PD array (K = 9), and FIG. 7B illustrates a case where 13 PDs are located in a circular PD array (K = 13). ) Is a diagram showing a light source position estimation error result when 17 PDs are located in a circular PD array (K = 17).

Referring to FIGS. 7A to 7C, as the number of PDs increases, the position estimation error of the light source to which the DOA algorithm is applied decreases.

Embodiments and modifications described above may be combined. Accordingly, the embodiments may not be implemented alone, but may be implemented in combination as necessary. Such a combination can be easily implemented by those skilled in the art after reading the present specification, and the combination will not be described in detail below. However, even if not described, it is not to be excluded from the present invention, it should be construed as being included in the scope of the present invention.

Embodiments and modifications described above may be implemented through various means. For example, embodiments of the present invention may be implemented by hardware, firmware, software, or a combination thereof.

For a hardware implementation, the method according to embodiments of the present invention may be implemented in one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs) , Field programmable gate arrays (FPGAs), processors, controllers, microcontrollers, microprocessors, and the like.

In the case of an implementation by firmware or software, the method according to embodiments of the present invention may be implemented in the form of a module, a procedure or a function for performing the functions or operations described above. The software code can be stored in a memory unit and driven by the processor. The memory unit may be located inside or outside the processor, and may exchange data with the processor by various well-known means.

For example, a method in accordance with the present invention may be implemented in software (e.g., flash memory, hard disk, etc.) that can be stored in a storage medium And may be implemented as codes or instructions within the program. This will be described with reference to FIG.

8 is a diagram illustrating an internal block diagram of an optical transmitter and an optical receiver to which an embodiment of the present disclosure can be applied.

The optical transmitter (or light source 110) includes an optical transmitter 111, a controller 112, and a memory 113.

The optical transmitter 111 modulates an electrical signal into an optical signal in order to transmit the optical signal.

Here, various modulation schemes may be applied. For example, modulation schemes include OOK (On Off Keying), Pulse Width Modulation (PWM), Pulse Position Modulation (PPM), Pulse Amplitude Modulation (PAM), Amplitude Shift Keying (ASK), and M-ary Phase Shift (M-PSK). Keying), M-ary Quadrature Amplitude Modulation (M-QAM), and the like.

The controller 112 implements the proposed function, process and / or method.

The memory 113 may be connected to the control unit 112 to store a protocol or parameter for performing optical communication.

The optical receiver 120 includes an optical receiver 121, a controller 122, and a memory 123.

First, the light receiver 121 may be a circular PD array including at least one PD. In addition, the optical receiver 121 converts (or demodulates) the optical signal into an electrical signal. Here, the demodulation method uses the same method as the modulation method in the optical transmitter 111. That is, the demodulation method includes OOK (On Off Keying), Pulse Width Modulation (PWM), Pulse Position Modulation (PPM), Pulse Amplitude Modulation (PAM), Amplitude Shift Keying (ASK), and M-ary Phase Shift Keying (M-PSK). ) Or M-ary Quadrature Amplitude Modulation (M-QAM).

In addition, the optical receiver 120 may be fixed or mobile.

The controller 122 implements the proposed function, process and / or method.

The memory 123 may be connected to the controller 122 and store a protocol or parameter for performing optical communication.

In addition, the optical receiver 120 may include a display unit, a user interface unit, and the like.

In addition, the display unit displays various information of the optical receiver, and may use well-known elements such as liquid crystal display (LCD) and organic light emitting diodes (OLED). The user interface may be a combination of a well-known user interface such as a keypad or a touch screen.

The controllers 112 and 122 may include application-specific integrated circuits (ASICs), other chipsets, logic circuits, and / or data processing devices. The memories 113 and 123 may include read-only memory (ROM), random access memory (RAM), flash memory, memory cards, storage media and / or other storage devices. When the embodiment is implemented in software, the above-described techniques may be implemented with modules (processes, functions, and so on) that perform the functions described above. The module may be stored in the memories 113 and 123 and executed by the controllers 112 and 122.

The memories 113 and 123 may be inside or outside the controllers 112 and 122, and may be connected to the controllers 112 and 122 by various well-known means.

In addition, it is to be noted that the technical terms used herein are merely used to describe particular embodiments and are not intended to limit the present invention. It is also to be understood that the technical terms used herein are to be interpreted in a sense generally understood by a person skilled in the art to which the present invention belongs, Should not be construed to mean, or be interpreted in an excessively reduced sense. In addition, when the technical terms used herein are incorrect technical terms that do not accurately express the spirit of the present invention, they should be replaced with technical terms that can be understood correctly by those skilled in the art. In addition, the general terms used in the present invention should be interpreted according to a predefined or prior context, and should not be construed as being excessively reduced.

Also, the singular forms "as used herein include plural referents unless the context clearly dictates otherwise. In the present application, the term "comprising" or "comprising" or the like should not be construed as necessarily including the various elements or steps described in the specification, Or may be further comprised of additional components or steps.

Furthermore, terms including ordinals such as first, second, etc. used in this specification can be used to describe various elements, but the elements should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component.

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, but other elements may be present in between. 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 embodiments described above are the components and features of the present invention are combined in a predetermined form. Each component or feature shall be considered optional unless otherwise expressly stated. Each component or feature may be implemented in a form that is not combined with other components or features. It is also possible to construct embodiments of the present invention by combining some of the elements and / or features. The order of the operations described in the embodiments of the present invention may be changed. Some configurations or features of certain embodiments may be included in other embodiments, or may be replaced with corresponding configurations or features of other embodiments. It is clear that the claims that are not expressly cited in the claims may be combined to form an embodiment or be included in a new claim by an amendment after the application.

100: optical communication system 112,122: control unit
110: optical transmission device 113,123: memory
111: light transmission unit
120: light receiving device
121: Light receiving part

Claims (7)

A method for estimating the position of a light source in a wireless access system,
Receiving an optical signal from the light source via a circular array, the circular array comprising at least one photo detector (PD);
Calculating the power received at each photodetector of the circular array;
Determining a first photodetector and a second photodetector in the circular array using the received power of each photodetector,
The first photo detector is a photo detector having a maximum received power, and the second photo detector is a photo detector positioned at both sides of the first photo detector; And
Estimating the position of the light source using the determined received power of the first photodetector and the second photodetector. The method of claim 1,
The position of the at least one photodetector is a position on the circular array according to

A method characterized by the fact that

Here, R represents the radius of the circular PD array, K represents the number of PDs, i is the index of the PD, i = 1, 2, ..., K. The method of claim 1,
The power received at each photo detector is calculated according to the following equation.

Here, P _t represents the transmission power of the light source, H _i (0) represents the channel DC gain between the light source and the optical receiver, and N (i) represents noise. The method of claim 1, wherein the position of the light source,
It is estimated according to the following equation.

here,

Lt; / RTI >

C _m represents a weighting coefficient. A method for estimating the position of a light source in a wireless access system,
Receiving an optical signal of the light source through a first circular PD array and a second circular PD array, wherein the first circular array and the second circular array are comprised of at least one photo detector (PD);
Calculating power received at each photodetector of the first circular array and the second circular array;
Determining a first photodetector and a second photodetector in each of the first circular array and the second circular array using the received power of each photodetector;
The first photo detector is a photo detector having a maximum received power, and the second photo detector is a photo detector positioned at both sides of the first photo detector; And
Estimating the position of the light source using the received power of the first photodetector and the second photodetector respectively determined in the first circular array and the second circular array. The method of claim 5, wherein estimating the position of the light source comprises:
Calculating an angle at which the received optical signal is incident on the first circular array and the second circular array;
Measuring a distance between the first circular array and the second circular array; And
Estimating a position of the light source using the calculated angle and the measured distance by using a triangulation method, wherein the calculated angle includes:
Is calculated according to the following equation.

here,

Lt; / RTI >

C _m represents a weighting coefficient. In the light receiving device for estimating the position of the light source,
An optical receiver for receiving an optical signal from the light source; And
Including a control unit connected to the light receiving unit,
The light receiving unit includes a circular array consisting of at least one photo detector (PD), and the control unit,
Compute the power received at each photodetector of the circular array, determine the first and second photodetectors in the circular array using the received power of each photodetector, and determine the determined first and second photodetectors. 2 controls to estimate the position of the light source using the received power of the photodetector,
And the first photodetector is a photo detector having a maximum reception power, and the second photo detector is a photo detector positioned at both sides of the first photo detector.

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