KR20140094396A - Method for identifying led-id tag in in led-id system - Google Patents

Abstract

The present invention relates to a method for identifying LED-ID tags in an LED-ID system wherein the LED-ID tags can be identified from LED-ID readers if data in the LED-ID readers collide due to the interference among a plurality of LED-ID tags. According to the present invention, the method for identifying LED-ID tags in an LED-ID system having the LED-ID tags and the LED-ID readers includes the steps of setting the number of LED-ID tags (β) to be identified and the interference probability (Q) thereof in the LED-ID readers; transmitting data in the LED-ID tags to the LED-ID readers according to the data request of the LED-ID readers; determining whether the data collision occurs due to the interference among the LED-ID tags upon the data transmission of the LED-ID tags in the LED-ID readers; assigning new time slot to the LED-ID tags upon the data collision; determining whether the LED-ID tag on which data interference has occurred is identified using the set interference probability (Q) when the data collision does not occur; and if the LED-ID tag on which the data interference has occurred is identified, determining all LED-ID tags have been identified.

Description

[0001] The present invention relates to a method of identifying an LED-ID tag in an LED-ID system,

The present invention relates to an LED-ID system, which minimizes data collision in an LED-ID reader due to the occurrence of interference between a plurality of LED-ID tags in an LED-ID system, ID < / RTI > identification in an LED-ID system that allows the LED-ID tag to be accurately identified.

The LED-ID technology can be defined as a new LED light source-based identification (ID) technique for transmitting and receiving tag information using a light emitting diode (LED) light source. The LED-ID technology is a new optical-wireless technology that uses the LED that is receiving the spotlight as the next generation illumination and gives the function of transmitting the ID information in addition to the illumination function. It is a new technology that can acquire desired ID information in any place where the LED light source exists to be.

This LED-ID does not need to acquire a new frequency license like existing radio technology using RF (Radio Frequency), does not have frequency interference by existing RF, and can use a wide band of LED light. In addition, when visible light is used, it is possible to visually confirm whether or not communication is performed, so that the physical security function is excellent and high-speed multimedia data can be transmitted. Recently, the use of LEDs is spreading in various fields, and LED-ID technology can be applied to such LED-based facilities.

Conventional LED related research has been focused on communication combined with illumination, such as Visible Light Communication (VLC) technology. However, despite the many advantages and possibilities described above, research on LED-ID technology is still in its early stage. For example, in a case where a plurality of LED-ID tags and an LED-ID reader exist together, transmission data of the LED-ID tag due to interference between the FOV (field of view) of the LED-ID tag conflicts There is no solution to the problem. Also, in the LED-ID system, a technique for identifying the LED-ID tag in the case of such a collision is not shown. In the case of the home network field, which is expected to greatly increase in the future, research and development of such collision prevention and LED-ID tag identification technology are required.

The present invention has been proposed in response to the above-mentioned problems of the related art and the demand for technology development. It is an object of the present invention to provide an LED- The object of the present invention is to provide a method of identifying an LED-ID tag in an LED-ID system that enables accurate identification of a collided LED-ID tag.

According to an aspect of the present invention, there is provided a method of identifying an LED-ID tag in an LED-ID system,

A method of identifying an LED-ID tag in an LED-ID system including a plurality of LED-ID tags and an LED-ID reader, the method comprising the steps of: Setting an interference probability (Q); Transmitting data to the LED-ID reader in response to a data request of the LED-ID reader in the plurality of LED-ID tags; Determining whether data collision occurs due to interference between the plurality of LED-ID tags in data transmission of the plurality of LED-ID tags in the LED-ID reader; Wherein the LED-ID tag is allocated a new time slot when the collision occurs; Determining whether an interfering LED-ID tag is identified by comparing an interference probability of the non-colliding LED-ID tag with the interference probability (Q) of the set LED-ID tag in the non-collision; And if the interfering LED-ID tag has been identified, processing all LED-ID tags as identified; .

In the present invention, the step of transmitting data from the LED-ID tag to the LED-ID reader may include: transmitting a wake-up signal from the LED-ID reader to the plurality of LED-ID tags in the ID detection mode; Switching from an illumination mode to an illumination / data transmission mode upon receiving a wake-up signal from the LED-ID reader in the LED-ID tag; Transmitting the tag ID and data of the LED-ID tag to the LED-ID reader when switching from the LED-ID tag to the illumination / data transmission mode; Switching from an ID detection mode to a data reception mode when the LED-ID reader receives the tag ID and data; Requesting data transmission from the LED-ID reader to the LED-ID tag; Transmitting data from the LED-ID tag to the LED-ID reader; And transmitting an acknowledgment (ACK) from the LED-ID reader to the LED-ID tag; .

In the present invention, before the step of requesting data transmission from the LED-ID reader to the LED-ID tag and the step of transmitting data from the LED-ID tag to the LED-ID reader, And sending a beacon message to the LED-ID reader.

In the present invention, the step of determining whether the interfering LED-ID tag is identified may include determining whether the interference probability of the colliding LED-ID tag is greater than the interference probability Q of the set LED-ID tag; And determining that the interfering LED-ID tag is identified if the interference probability is greater than the interference probability (Q) of the set LED-ID tag as a result of the determination. .

In the present invention, when the collision occurs, the step of allocating the new time slot to the LED-ID tag may include the step of determining the time of the next transmission cycle to re-identify the other LED- Select a slot.

The LED-ID tag identification method in the LED-ID system according to the present invention has the following effects.

According to the present invention, it is possible to accurately identify the LED-ID tag even in case of data collision due to interference in the LED-ID system.

Also, according to the present invention, when data is transmitted to the LED-ID reader using the same time slot in a plurality of LED-ID tags, collision can be avoided even when data collision occurs due to interference.

1 is a schematic configuration diagram of an LED-ID system according to an embodiment of the present invention;
2 is a block diagram of a configuration of an LED-ID tag according to an embodiment of the present invention.
3 is a block diagram of an LED-ID reader according to an embodiment of the present invention.
4 is a flowchart of communication between the LED-ID tag and the reader according to the present invention.
5 is a flowchart illustrating an LED-ID tag identification process according to the present invention.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. In the following description, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

1 is a schematic configuration diagram of an LED-ID system according to an embodiment of the present invention.

1, the LED-ID system according to the embodiment of the present invention includes a plurality of LED-ID tags 110, a plurality of LED-ID readers 120, a tag management unit 130 ), A core network 140, an LED-ID server 150, and an application server 160.

The LED-ID tag 110 may preferably be implemented as a lighting device that uses an LED as a light source and includes a tag ID or predetermined data therein. The LED-ID reader 120 transmits and receives data to and from a plurality of LED-ID tags 110 using visible light communication through a wireless optical channel. The LED-ID reader 120 may be implemented as a user terminal such as a cellular phone.

The LED-ID reader 120 requests each of the plurality of LED-ID tags 110 with tag ID or predetermined data using visible light communication, and the LED-ID tag 110 transmits the tag ID or the tag ID, And transmits the data to the corresponding LED-ID reader 120 through visible light communication. In addition, a plurality of LED-ID readers 120 may receive data requests from a plurality of LED-ID tags 110 and transmit them to each LED-ID tag 110.

As described above, the transmission medium in the LED-ID system according to the present invention preferably uses visible light, and the structure and function of Media Access Control (MAC) and Physical Layer (PHY) It conforms to the 802.15.7 standard.

ID tag 110 may be installed in a room having a predetermined space, a museum, a city hall, an exhibition hall, etc. The operation of each of the LED-ID tags 110 is managed and controlled by the tag management unit 130 do. In particular, the tag management unit 130 performs operations in the LED-ID system and a resource allocation function of the system.

The core network 140 is a communication network that connects the tag management unit 130 and the LED-ID server 150 or the application server 160. The core network 140 may be implemented as a wired network or a wireless network and may transmit data requested by the LED-ID tag 110 and the LED-ID reader 120 to the LED-ID server 150 or the application server 160, And the like.

The LED-ID server 150 identifies the user's ID using the tag ID of the LED-ID tag 110 transmitted from the LED-ID reader 120, recognizes the location of the user, And the location of the user.

The application server 160 transmits the data required by the LED-ID tag 110 to the LED-ID reader 120 based on the ID of the user and the location of the user identified by the LED-ID server 110 .

2 is a block diagram of an LED-ID tag according to an embodiment of the present invention.

2, the LED-ID tag 110 according to the present invention includes a storage unit 111, a transmitter 112, a receiver 113, a power unit 114, and a tag controller 115.

The storage unit 111 stores the tag ID of the LED-ID tag 110 or predetermined data. At this time, the tag ID is unique identification information allocated for each LED-ID tag 110. In addition, the storage unit 111 stores the data received from the LED-ID reader 120.

The transmission unit 112 transmits the tag ID or data stored in the storage unit 111 to the LED-ID reader 120 using visible light communication through a wireless optical channel. Further, the transmission unit 112 causes the LED illumination to emit light. To this end, the transmission unit 112 includes an LED unit 112a, an LED driver 112b, an illumination adjustment unit 112c, and a transmission processing unit 112d. The LED unit 112a is constituted by at least one LED array and allows visible light to be irradiated from the light source, and the LED driver 112b drives the LED unit 112a so that visible light is irradiated from the light source. The illumination adjustment unit 112c adjusts the illumination of the LED. That is, the LED unit 112a can be used as illumination in the absence of data transmission, and the illumination adjustment unit 112c controls the illumination of the LED-ID tag 110 when the LED-ID tag 110 does not transmit or receive data. The transmission processing unit 112d processes the tag ID or predetermined data stored in the storage unit 111 and transmits it to the LED-ID reader 120. [ In order to achieve this, the data transmitted from the LED-ID server 150 or the application server 160 is modulated into signals of respective modulation schemes according to various modulation schemes, and modulated by loading the signals at a carrier frequency of a specific frequency band . Further, an electric signal is converted into an optical signal in a visible light region, and visible light is transmitted as a signal.

The receiving unit 113 receives the data received from the LED-ID reader 120 via the wireless optical channel and stores the received data in the storage unit 111. To this end, the reception unit 113 includes a photodetector 113a and a reception processing unit 113b. The photodetector 113a receives an optical signal transmitted from the LED-ID reader 120 through a wireless optical channel, converts the optical signal into an electrical signal, and outputs the electrical signal. The photodetector 113a is composed of a photoelectric conversion element such as a photodiode or the like which is mainly used for optical signal detection by generating a current corresponding to a received optical signal as one of semiconductor diodes. The reception processing unit 113b processes the data corresponding to the electric signal detected by the photodetector 113a and stores the processed data in the storage unit 111. [

The power supply unit 114 supplies power necessary for the operation of the LED-ID tag 110. The power is supplied to the transmitting unit 112, the receiving unit 113, and the tag controlling unit 115, which will be described later.

The tag control unit 115 controls the overall operation of the LED-ID tag 110. The tag control unit 115 controls the operation to efficiently perform the illumination, the optical signal transmission, the tag ID, or the predetermined data transmission / reception.

3 is a block diagram of an LED-ID reader according to an embodiment of the present invention.

3, the LED-ID reader 120 according to the present invention includes a receiving unit 121, a transmitting unit 122, a power unit 123, and a reader controller 124.

The receiving unit 121 receives the tag ID or predetermined data received from the LED-ID tag 110 through the wireless optical channel. The tag ID or data thus received may be transmitted to the LED-ID server 150 later. The receiving unit 121 includes a photodetector 121a and a receiving processing unit 121b. The photodetector 121a receives an optical signal transmitted from the LED-ID tag 110 through a wireless optical channel, converts the optical signal into an electrical signal, and outputs the electrical signal. The photodetector 113a is composed of a photoelectric conversion element such as a photodiode or the like which is mainly used for optical signal detection by generating a current corresponding to a received optical signal as one of semiconductor diodes. The reception processing unit 121b processes data corresponding to the electric signal detected by the photodetector 121a.

The transmitting unit 122 transmits the data transmitted from the LED-ID server 150 or the application server 160 to the LED-ID tag 110 through the wireless optical channel. To this end, the transmission unit 122 includes a transmission processing unit 122a. The transmission processing unit 122a modulates the data transmitted from the LED-ID server 150 or the application server 160 into signals of respective modulation methods according to various modulation schemes and transmits the signals to a carrier frequency To modulate it. Further, the transmission processing unit 122a converts the modulated signal into an optical signal in the visible light region, and transmits the optical signal as visible light through the wireless optical channel.

Meanwhile, the photodetectors 113a and 121a in the LED-ID tag 110 and the reader 120 according to the embodiment of the present invention directly detect the line-of-sight (DD) It is possible.

4 is a communication flow diagram between the LED-ID tag and the LED-ID reader according to the present invention.

4, in an embodiment of the present invention, the LED-ID reader 120 transmits a wake-up signal to the LED-ID tag 110 for communication with the LED-ID tag 110 in the ID detection mode S10). Then, the LED-ID tag 110 is switched from the illumination mode to the illumination / data transmission mode by the wake-up signal, and generates a beacon message including the tag ID or predetermined data and transmits the beacon message to the LED-ID reader 120 S11). Here, the LED-ID tag 110 preferably receives the wake-up signal only in the illumination mode. The LED-ID reader 120 is switched from the ID detection mode to the data reception mode by receiving such a beacon message. The mode conversion of the LED-ID tag 110 and the LED-ID reader 120 is managed and advanced by the tag management unit 130.

Thereafter, the LED-ID tag 110 allocates a time slot for data transmission in an illumination / data transmission mode and sends out a beacon message (S12). That is, a proper time slot is allocated through the position information of the LED-ID reader 120 and a beacon message is sent. At this time, the number of time slots that can be allocated is variable and the maximum number of nodes is preferably set. The reason is that if a large number of time slots are allocated without limitation, a large amount of time is allocated to data reception, and real time performance can not be guaranteed. Thus, the LED-ID reader 120 requests the tag ID or data with the LED-ID tag 110 (S13). When a data request is received from the LED-ID tag 110, a resource is allocated for data transmission between the LED-ID reader 120 and the LED-ID tag 110 (S14). Thereafter, the LED-ID tag 110 transmits a beacon message (S15) and transmits the data requested by the LED-ID reader 120 (S15). Then, the LED-ID reader 120 receives the corresponding data and transmits an ACK message to the LED-ID tag 110 (S16).

In the communication between the plurality of LED-ID tags 110 and the LED-ID reader 120, the LED-ID reader 120 may be interfered with each other within the operation range between the adjacent LED- A collision may occur. To solve this collision problem, the present embodiment uses a slotted ALOHA protocol. In this slotted ALOHA protocol, when there is data to be transmitted from the plurality of LED-ID tags 110 sharing the wireless optical channel to the LED-ID reader 120, the tag is configured to be time- And performs data communication on a frame-by-frame basis. This makes it possible to divide the time during which a plurality of LED-ID tags 110 respond to a transmission command of the LED-ID reader 120 into slots of a fixed size, Tag ID or data, and the tag is recognized by configuring a plurality of slots into one frame.

5 is a flowchart illustrating an identification process of an LED-ID tag when interference occurs according to an embodiment of the present invention.

5, in the method of identifying an LED-ID tag according to an embodiment of the present invention, when the interference occurs, the number of LED-ID tags 110 to be identified and the interference probability, (Step S20). That is, when the interference occurs, the LED-ID reader 120 can set the number of LED-ID tags 110 to be identified and the interference probabilities Q thereof. Here, the interference probability Q is a probability that an interference occurs due to the movement of the LED-ID reader 120 when a signal is transmitted from the LED-ID reader 120 to the LED-ID tag 110, The interference level is a reference value for interference that is difficult or impossible to identify. This can be determined as a preset value in the LED-ID system. Thereafter, the LED-ID tag 110 selects an arbitrary time slot (S21) and transmits data according to a data transmission request from the LED-ID reader 120 (S22). At this time, when data is transmitted using the same time slot in a plurality of LED-ID tags 110, data collision occurs in the LED-ID reader 120. Accordingly, the LED-ID reader 120 determines whether a collision has occurred (S23), and if there is a collision, the LED-ID tag 110 where the collision occurred, proceeds to S21 to identify again until all other tags are identified The time slot of the period is selected (S21). However, if the collision does not occur, if the interference probability of the non-collided tag is smaller than the interference probability Q set in step S20, it is determined that all the LED-ID tags 110 have been successfully identified (S24) The process proceeds to step S21.

If an interference probability exists between adjacent LED-ID tags 110, Q is defined as the probability of non-identified tags due to interference. Thus, the probability of the identified tag is (1-Q). If interference occurs, the tag may not be identified. The formula for the tag identified in each round is denoted (1-Q) / e. Therefore, the formula for the tag that remains unidentified is [1- (1-Q) / e]. Assuming that the total number of tags to be identified is β and the total number of rounds for identifying all the LED-ID tags is ri, the number identified in the initial number of all tags β is β [1- ( 1-Q) / e] ^ri . At this time, when the target tag to be identified is?, Tags of? At this time, ri can be calculated as shown in Equation (1) below.

Here, the number of time slots T (?) Necessary for identifying all the? Tags can be calculated as the value of the unidentified tag for each round as shown in Equation (2) below.

As described above, in the present invention, when data is transmitted to the LED-ID reader 120 using the same time slot in a plurality of LED-ID tags 110, even when data collision occurs due to interference, .

While the invention has been shown and described with reference to certain preferred embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments. Those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope of the appended claims, The genius will be so self-evident. Accordingly, the true scope of the present invention should be determined by the technical idea of the appended claims.

Recently, there is a growing interest in LED-ID technology. Unlike conventional RFID technology, LED-ID technology can utilize a wide range of LED light, has excellent security functions, and can transmit high-speed multimedia data. LED-ID technology can be applied to LED-based facilities such as home appliances, mobile communication devices, lighting, advertising, medical, environmental, and agricultural and marine products. It is useful for excellent point-to-point or point-to-multipoint communication, indoor LBS (Locatio Based Service), and information broadcasting. Especially, it is expected that synergy effect will be gained through mutual exchange by applying to home network field and LED lighting field, which are expected to show great growth in the future.

110: LED-ID tag 120: LED-ID reader
130: tag management unit 140: core network
150: LED-ID server 160: application server

Claims (5)

A method of identifying an LED-ID tag in an LED-ID system including a plurality of LED-ID tags and an LED-ID reader,
Setting a number (β) and an interference probability (Q) of a plurality of LED-ID tags to be identified by the LED-ID reader;
Transmitting data to the LED-ID reader in response to a data request of the LED-ID reader in the plurality of LED-ID tags;
Determining whether data collision occurs due to interference between the plurality of LED-ID tags in data transmission of the plurality of LED-ID tags in the LED-ID reader;
Wherein the LED-ID tag is allocated a new time slot when the collision occurs;
Determining whether an interfering LED-ID tag is identified by comparing an interference probability of the non-colliding LED-ID tag with the interference probability (Q) of the set LED-ID tag in the non-collision; And
If the interfering LED-ID tag has been identified, processing all LED-ID tags as identified; Gt; LED-ID < / RTI > The method according to claim 1,
The step of transmitting data from the LED-ID tag to the LED-
Transmitting a wake-up signal from the LED-ID reader to the plurality of LED-ID tags in the ID detection mode;
Switching from an illumination mode to an illumination / data transmission mode upon receiving a wake-up signal from the LED-ID reader in the LED-ID tag;
Transmitting the tag ID and data of the LED-ID tag to the LED-ID reader when switching from the LED-ID tag to the illumination / data transmission mode;
Switching from an ID detection mode to a data reception mode when the LED-ID reader receives the tag ID and data;
Requesting data transmission from the LED-ID reader to the LED-ID tag;
Transmitting data from the LED-ID tag to the LED-ID reader; And
Transmitting an ACK from the LED-ID reader to the LED-ID tag; Gt; LED-ID < / RTI > 3. The method of claim 2,
The method comprising: requesting data transmission from the LED-ID reader to the LED-ID tag; and transmitting data from the LED-ID tag to the LED-
Further comprising transmitting a beacon message from the LED-ID tag to the LED-ID reader. The method according to claim 1,
The step of determining whether the interfering LED-ID tag is identified comprises:
Determining whether an interference probability of the collision-induced LED-ID tag is greater than an interference probability (Q) of the set LED-ID tag; And
Determining that the interfering LED-ID tag is identified if the interference probability is greater than an interference probability (Q) of the set LED-ID tag; Gt; LED-ID < / RTI > The method according to claim 1,
Wherein when the collision occurs, the LED-ID tag is allocated a new time slot,
Wherein the time slot of the next transmission period is selected for re-identification until all of the other LED-ID tags are identified in the collided LED-ID tag.

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