KR100706180B1 - Method of accessing channel for rfid reader and computer-readable medium having thereon program performing function embodying the same - Google Patents

Abstract

The present invention includes the steps of (a) checking the beacon channel set in the RFID frequency band, (b) determining whether the RFID frequency band can be occupied based on the beacon channel test result, and (c) the RFID frequency band The present invention relates to a channel access method of an RFID reader including transmitting a signal to the beacon channel when occupied.

According to the present invention, the beacon channel indicating whether the RFID frequency band is occupied without performing the band LBT can be easily checked to determine whether the RFID frequency band can be occupied, and the RFID reader according to the simultaneous occupancy of the channel through the channel inspection. By reducing the possibility of interference or collision between them, it is possible to prevent the RFID reader from lowering the recognition rate and malfunctioning of the RFID system.

RFID, LBT, Beacon Channel, Channel Occupancy, Signal Level

Description

FIELD OF ACCESSING CHANNEL FOR RFID READER AND COMPUTER-READABLE MEDIUM HAVING THEREON PROGRAM PERFORMING FUNCTION EMBODYING THE SAME}

1 is a diagram illustrating an environment to which a channel access method of an RFID reader according to the present invention is applied.

2 is an exemplary flowchart of a channel access method of an RFID reader according to the present invention;

3 is a diagram illustrating a beacon channel setting in an RFID frequency band in the channel access method of the RFID reader according to the present invention.

<Description of the symbols for the main parts of the drawings>

100: zone 110: portable terminal

120: fixed RFID reader 130: mobile communication terminal

The present invention relates to a method of accessing a channel of an RFID reader and a computer-readable recording medium recording a program for realizing the same. More specifically, the present invention relates to a beacon channel indicating whether an RFID frequency band is occupied without performing band LBT. It is possible to easily check whether the RFID frequency band can be occupied and reduce the possibility of interference or collision between RFID readers due to the simultaneous occupancy of the channel through the channel inspection to prevent the RFID reader's recognition rate and malfunction of the RFID system. A method of accessing a channel of a reader and a computer-readable recording medium having recorded thereon a program for realizing the same.

A radio frequency identification (hereinafter referred to as "RFID") system refers to a system that processes information by identifying a tag in a thin flat form attached to an object in a contactless manner through a radio signal.

Such an RFID system consists of an antenna, an RFID tag, also referred to as a transponder, and a transceiver, often integrated into an RFID reader. In this case, the RFID reader uses radio frequency waves to transmit a signal for activating the RFID tag. When the RFID tag is activated, the RFID tag transmits its data to the RFID reader through an antenna.

Recently, due to the development of technologies such as standardization of RFID, reduction in manufacturing cost, and extension of reading distance, applications of RFID systems in the industry are gradually increasing.

These RFID standards differ from country to country. For example, in Europe, the frequency band between 865 MHz and 868 MHz is separated into a channel bandwidth of 200 kHz per channel, and a total of 15 channels are used. In the United States, the ISM (Industrial, Scientific, and Medical) As the band is used as an RFID frequency band, more than 50 channels are used with a channel bandwidth of 500 kHz per channel. Korea also selects a channel bandwidth of 200 kHz per channel in the 5.5 MHz frequency band between 908.5 MHz and 915 MHz. Korea has a channel bandwidth of 200 kHz, similar to the European method, but since the entire frequency band uses 5.5 MHz, which is wider than Europe, there are 27 channels except for the upper and lower guard bands. There are many states.

The RFID system using the frequency of the 900 MHz band has the advantage of having a wide recognition distance to enable a variety of application services, while the interference with heterogeneous wireless communication systems such as mobile communication in the 900 MHz and the multiple RFID readers In the existing multi-reader environment, the system performance is limited due to interference and collision between RFID readers.

In particular, the fixed reader is improving by using a spectrum mask within and outside the RFID frequency band to overcome this disadvantage.

However, interference or collision between RFID readers generated in a multi-reader environment that cannot be solved even by such a spectral mask causes disadvantages such as deterioration of the recognition rate of the RFID reader and malfunction of the RFID system. Therefore, to overcome these shortcomings, air channel access methods such as Frequency Hopping (FH) or List Before Talking (LBT) are developed and standardized for related technologies. I'm trying to.

For example, in Europe, the LBT method is used, in the United States, the FH method is used, and in Korea, the LBT method and the FH method are used in parallel.

A more detailed description of the List Before Talking (LBT) method is as follows.

In a multi-reader environment in which multiple RFID readers and RFID tags are placed, the LBT method performs channel monitoring before each RFID reader approaches a channel in the RFID frequency band, so that if the channel is accessible, the LBT method performs a round operation during the channel occupancy time. This is a method of repeatedly executing a preamble-command-CW.

The LBT may be divided into a band LBT and a channel LBT. The band LBT is to check whether other RFID readers exist for the entire RFID frequency band, for example, 908.5 MHz to 915 MHz band in Korea, and the channel LBT is to check whether the corresponding channel is used by another RFID reader.

This band LBT is performed by monitoring each channel because it cannot simultaneously monitor a plurality of channels of the RFID frequency band. Therefore, when performing band LBT, a lot of time is consumed.

In addition, even when performing band LBT, interference or collision between RFID readers may occur. For example, assume that RFID reader A and RFID reader B perform this band LBT. In this case, first, the RFID reader A sequentially monitors each channel to perform band LBT, and then the RFID reader B may perform band LBT on each channel. Due to the difference in the start time of the band LBT, each RFID reader A and the RFID reader B determine that another RFID reader does not exist while performing the band LBT. Therefore, the channel LBT occupies the channel after the band LBT ends. Can be used simultaneously or sequentially. In this case, two RFID readers occupy channels simultaneously in the RFID frequency band, and this simultaneous occupancy increases the possibility of interference or collision between the RFID readers, such as deterioration of the recognition rate of the RFID reader and malfunction of the RFID system. Cause disadvantages.

It is an object of the present invention to check the beacon channel indicating whether the RFID frequency band is occupied without performing the band LBT to easily determine whether the RFID frequency band can be occupied and the RFID reader according to the simultaneous occupancy of the channel through the channel inspection. The present invention provides a method for accessing a channel of an RFID reader to reduce the possibility of interference or collision between the RFID readers and to prevent the RFID reader from decreasing its recognition rate and malfunctioning of the RFID system.

Another object of the present invention is to provide a computer readable recording medium having recorded thereon a program for realizing each step of the channel access method of the RFID reader.

In order to achieve the above technical problem, the present invention includes the steps of (a) checking the beacon channel set in the RFID frequency band, (b) determining whether the RFID frequency band occupancy based on the beacon channel test result and and (c) transmitting a signal to the beacon channel when the RFID frequency band is occupied.

 In the channel access method of the RFID reader according to the present invention, (d) if the RFID frequency band is not occupied may further comprise the step of waiting for a certain time and then jumping to the step (a).

In addition, in the channel access method of the RFID reader according to the present invention, the beacon channel may be any channel predetermined in the RFID frequency band.

In addition, in the channel access method of the RFID reader according to the present invention, the step (a) may include (a-1) checking the signal level of the beacon channel.

In addition, in the channel access method of the RFID reader according to the present invention, the step (b), (b-1) if the signal level is less than the predetermined band use threshold value, the RFID frequency band is determined to occupy the state and the If greater than the band usage threshold value may include determining the non-occupied state of the RFID frequency band.

In the channel access method of the RFID reader according to the present invention, after the step (c), (e) checking whether any channel in the RFID frequency band is occupied, and (f) the arbitrary channel is occupied. If it is not busy, the method may include determining the arbitrary channel as a use channel.

In the channel access method of the RFID reader according to the present invention, the method may further include (g) waiting for an arbitrary time before step (e).

In the channel access method of the RFID reader according to the present invention, after the step (f), (h) waiting for a certain time, (i) checking whether the use channel is occupied, (j The method may further include accessing to the use channel if the use channel is not occupied.

In the channel access method of the RFID reader according to the present invention, the step (e) includes (e-1) checking a signal level of the arbitrary channel, and the step (f) includes: f-1) determining the arbitrary channel as the use channel when the signal level of the any channel is equal to or less than a predetermined channel use threshold value.

In the channel access method of the RFID reader according to the present invention, the step (a) includes (a-1) checking the signal level of the beacon channel, and the step (e) includes (e) -1) checking the signal level of the arbitrary channel, wherein step (f) comprises: (f-2) if the signal level of the beacon channel is greater than a predetermined collision potential threshold; And determining the random channel as the use channel only when the magnitude of the signal level is equal to or less than a predetermined collision avoidance threshold.

In the channel access method of the RFID reader according to the present invention, after the step (c), (k) checking a plurality of channels in the RFID frequency band, and (l) using a channel among the plurality of channels The method may further include determining.

In addition, the channel access method of the RFID reader according to the present invention may further include the step of (m) waiting for any time before the step (k).

In the channel access method of the RFID reader according to the present invention, after the step (l), (n) waiting for any time, (o) checking whether the use channel is occupied, ( p) if the use channel is not occupied, may further include connecting to the use channel.

In the channel access method of the RFID reader according to the present invention, the step (k) includes (k-1) checking the signal levels of the plurality of channels, and the step (l) includes: l-1) determining, from among the plurality of channels, a channel whose signal level is equal to or less than a predetermined channel usage threshold value as the use channel.

In addition, in the channel access method of the RFID reader according to the present invention, the step (l-1) includes (l-2) determining the channel having the smallest signal level among the plurality of channels as the use channel. can do.

In the channel access method of the RFID reader according to the present invention, the step (a) includes (a-1) checking a signal level of the beacon channel, and the step (k) includes (k) -1) checking the signal levels of the plurality of channels, wherein step (l) comprises: (l-3) if the signal level of the beacon channel is greater than a predetermined collision potential threshold; Determining a channel having a minimum value of the signal level is less than a predetermined collision avoidance threshold value of the channel as the use channel.

The present invention also provides a computer-readable recording medium having recorded thereon a program for realizing each step of the channel access method of the RFID reader.

Hereinafter, a method of accessing a channel of an RFID reader of the present invention and a computer-readable recording medium recording a program for realizing the same will be described in more detail step by step with reference to the accompanying drawings.

1 is a diagram illustrating an environment to which a channel access method of an RFID reader according to the present invention is applied. As illustrated, it is assumed that a plurality of RFID readers 110a to 110b, 120a to 120b, and 130a to 130b are disposed in each of the zones 100a and 100b, and the zones 100a and 100b are separated by a predetermined distance.

The RFID readers 110a to 110b, 120a to 120b, and 130a to 130b are, for example, mobile RFID readers 110a to 110b having an RFID reading function in the portable terminals 110a to 110b or the mobile communication terminals 130a to 130b. 130a to 130b) or fixed RFID readers 120a to 120b connected to, for example, a POS system.

With reference to the application environment of Figure 1 will be described in detail the channel access method of the RFID reader according to the present invention.

2 is an exemplary flowchart of a channel access method of an RFID reader according to the present invention.

First, the RFID reader checks the beacon channel set in the RFID frequency band (S110).

To access the channel, the RFID reader must first check whether the RFID frequency band can be used. For example, the plurality of RFID readers 110a, 120a, 130a in the zone 100a of FIG. 1 are connected to other RFID readers in the zone 100a to occupy channels in the RFID frequency band to prevent a possibility of interference or collision with each other. It should be checked.

Confirmation of this is conventionally performed using band LBT. However, in the channel access method of the RFID reader according to the present invention, another RFID reader exists in the zone by checking the beacon channel set in the RFID frequency band without using the time-consuming band LBT by monitoring each channel. Check if the channel is occupied.

The beacon channel is a preset channel to identify whether there is an RFID reader occupying a channel in the RFID frequency band in the region.

That is, when there is an RFID reader occupying a channel in the RFID frequency band, the RFID reader transmits a signal to a beacon channel. In this case, the other RFID reader can easily check that the beacon channel is occupied by the channel in the RFID frequency band in the area without performing the band LBT as in the prior art.

FIG. 3 is a diagram illustrating a beacon channel setting in an RFID frequency band in the channel access method of the RFID reader according to the present invention.

As shown, there are a plurality of channels of a beacon channel and channels a to channel x in the RFID frequency band. 3 illustrates a case where the first channel in the RFID frequency band is set as a beacon channel.

In this case, if the beacon channel is set, the RFID readers 110a, 120a, and 130a in the zone 100a of FIG. 1 may be occupied by, or accessible to, channels in the RFID frequency band within the zone 100a. You can check by checking only the beacon channels.

Although this beacon channel is shown as the first channel in the RFID frequency band, it is also possible to set any channel among other channels as the beacon channel. For example, channel a may be set as a beacon channel. Even in this case, it is easy to check whether the RFID frequency band can be occupied through the beacon channel as long as information on the beacon channel setting can be obtained from the RFID reader in the zone.

Inspection of this beacon channel may be performed by simply examining the signal level of the beacon channel.

After checking the beacon channel through step S110, it is determined whether the RFID reader can occupy the RFID frequency band based on the result of the test (S120).

That is, suppose that, for example, the signal level of the beacon channel is checked in step S110. For example, if the beacon signal level is a very small value, it may mean that another RFID reader does not occupy the RFID frequency band in at least the corresponding area, so that it can occupy the RFID frequency band. Alternatively, if the signal level of the beacon channel is a small value compared to the case where other RFID readers occupy the same zone, for example, the beacon when the RFID readers 110a, 120a, and 130a in the zone 100a of FIG. If the signal level of the channel is detected but less than the signal level when another RFID reader in the zone 100a occupies the RFID frequency band, the beacon channel signal in the other zone 100b is propagated in the zone 100a and the beacon signal It can be assumed that the level occurs.

Therefore, the determination of whether the RFID frequency band can be occupied may be performed by comparing the signal level of the beacon signal with a predetermined threshold, that is, the band usage threshold.

The band usage threshold may be defined as the maximum value of the beacon channel signal level that can at least determine that no other RFID reader in the same zone occupies the RFID frequency band.

Therefore, if the signal level of the beacon signal is greater than the band usage threshold, it is considered that the other RFID reader occupies the RFID frequency band in the same area, and determines that the RFID frequency band is not occupied. If the level is less than or equal to the band usage threshold, it is determined that other RFID readers do not occupy the RFID frequency band in at least the same zone, and thus the RFID frequency band can be occupied.

If it is determined in step S120 that the RFID frequency band is occupied, the corresponding RFID reader transmits a signal to the beacon channel to inform another RFID reader in the same area that it occupies the RFID frequency band for a predetermined period of time (S130). This signal transmission may be configured to be transmitted as a level greater than the band usage threshold value so that it may be easily checked whether or not it is occupied by another RFID reader.

Through the signal transmission of the beacon channel, another RFID reader can easily check whether the RFID frequency band can be occupied without performing the band LBT through the signal level of the beacon channel.

In addition, if it is determined that the RFID frequency band is not occupied as a result of the checking in step S120, after waiting for a predetermined time (S140), the process returns to step S110 again to check the beacon channel.

For example, assume that the mobile RFID reader 110a and the fixed RFID reader 130a in the zone 100a continuously check the beacon channel in the environment of FIG. 1. In this case, if the beacon channel test determines that it cannot be occupied, the apparatus continues to wait, but once it is changed into an occupiable state, each of the mobile RFID reader 110a and the fixed RFID reader 130a determines that the RFID frequency band is occupied. At the same time, access to a channel in the RFID frequency band may occur. This simultaneous approach increases the possibility of interference or collision between the mobile RFID reader 110a and the fixed RFID reader 130a, resulting in problems such as a decrease in the recognition rate of the RFID reader and a malfunction of the RFID system.

Accordingly, in order to prevent such simultaneous access, the beacon channel may be checked again after waiting for an arbitrary time through step S140.

That is, each of the mobile RFID reader 110a and the fixed RFID reader 130a generates a random number, waits for a time corresponding to the random number, and checks the beacon channel again. Through this step S140, the time at which the mobile RFID reader 110a and the fixed RFID reader 130a start to inspect the beacon channel is different from each other, thereby reducing the possibility of simultaneous access.

 The channel access method of the RFID reader according to the present invention can easily determine whether the RFID reader can occupy the RFID frequency band without performing the conventional band LBT through the steps S110 to S140.

On the other hand, through the steps S110 to S140 it can be confirmed whether or not the occupancy of the RFID frequency band, whether or not to occupy the actual channel should be performed through a separate step.

That is, if another RFID reader in another zone uses a channel of an RFID frequency band, it is necessary to check whether the actual channel occupancy is possible to prevent interference or collision with other RFID readers in the other zone.

Therefore, when it is determined that the RFID frequency band can be occupied, a channel within the RFID frequency band is subsequently inspected (S150), and a channel to be used for actual data transmission, etc., according to the inspection result, must be determined (S160).

Examining channels in the RFID frequency band may be performed in the following steps.

First, select an arbitrary channel in the RFID frequency band and check whether the selected channel is occupied.

The identification of such channel occupancy may be performed by examining the signal level of the channel. As a result of checking the signal level of the channel, if the signal level of the channel is less than or equal to a predetermined threshold value, that is, the channel usage threshold value, the corresponding channel is determined as the use channel.

Here, the channel usage threshold value may be defined as the maximum value of the channel signal level that can determine that the corresponding channel can be used. These channel usage thresholds can be set to an appropriate size, but for example, the channel usage thresholds may be set to the general signal level of the beacon channel, i.e. the signal level value that can occur when an RFID reader in the same or another area transmits a signal to the beacon channel. If it is set to a very small value, the RFID reader may be configured to occupy the channel only when it is certain that the RFID reader of the same area as well as the other area does not use the channel.

Alternatively, a method of determining a channel to be used in consideration of both the signal level of the beacon signal and the signal level of the corresponding channel is possible.

That is, when checking the signal level of the beacon channel, when checking the signal level of the beacon channel, it is easy to check whether another RFID reader occupies the RFID frequency band in the same area. That is, the signal level of the beacon channel will be detected to be larger than the case where another RFID reader in the same area occupies the channel when the other RFID reader in the same area is occupied. Therefore, based on the magnitude of the signal level of the beacon channel, it is possible to determine whether another RFID reader occupies the RFID frequency band in the same zone or whether another RFID reader existing in the other zone is occupying the channel.

In this case, the RFID reader may be occupied by the RFID frequency band when compared to other RFID readers in the same zone, but may be occupied by another RFID reader to prevent interference or collision with another RFID reader occupying the RFID frequency band in another zone. The use of existing channels must be avoided.

Therefore, both the signal level of the beacon channel and the signal level of the channel can be examined to prevent such interference or collision.

In this case, it is determined whether the signal level of the beacon channel is greater than a predetermined collision possibility threshold value. Here, the collision possibility threshold value may be defined as a minimum value of a signal level of a beacon channel that may be determined to be likely to interfere or collide with an RFID reader existing in another zone.

If the signal level of the beacon channel is greater than the possible collision threshold, this may be considered to mean that there is a possibility of interference or collision with an RFID reader in another zone. Therefore, in this case, in order to minimize the possibility of interference or collision when occupying a channel, the channel is determined as a use channel only when the magnitude of the signal level of the channel is less than or equal to a predetermined collision avoidance threshold.

The collision avoidance threshold may be defined as a maximum value of a channel signal level that can be determined to prevent interference or collision with another RFID reader in a corresponding channel.

For example, in all cases where the signal level of the beacon channel is greater than the collision possibility threshold, it is determined that there is a possibility of collision with the RFID reader of another zone, so that the channel used by another RFID reader in the other zone, that is, the channel signal level is the collision avoidance threshold. Channels above the value are not determined as the use channel.

In addition, if the signal level of the beacon channel is below the collision possibility threshold, this may be considered to mean that there is no possibility of interference or collision with the RFID reader in another zone.

Therefore, the use channel may be determined using the aforementioned channel use threshold value rather than the collision avoidance threshold value.

In addition, the channel checking step for determining the use channel may be performed after waiting for an arbitrary time.

That is, assume that the mobile RFID reader 110a and the fixed RFID reader 130a in the zone 100a are simultaneously driven in the environment of FIG. 1 to simultaneously check the beacon channel. Or assume that the mobile RFID reader 110a and the fixed RFID reader 130a simultaneously check the beacon channel after waiting for a predetermined time through step S140. In this case, if the signal level of the beacon channel is less than the band usage threshold value, each of the mobile RFID reader 110a and the fixed RFID reader 130a simultaneously examines the channel through step S150 and sets the use channel through step S160 to occupy the channel. something to do. In this case, however, an unintentional simultaneous channel occupancy occurs between the mobile RFID reader 110a and the fixed RFID reader 130a, increasing the possibility of interference or collision between the RFID readers, thereby reducing the recognition rate of the RFID reader and malfunctioning of the RFID system. May occur.

Therefore, in order to prevent such a malfunction, a random number may be generated before the channel check of step S150, and the channel check may be performed through step S150 after waiting for a time according to the random number.

Using this step, even if two different RFID readers simultaneously check the beacon channel, there is a difference between the times of performing the actual channel check.

That is, the mobile RFID reader 110a performs a channel check after waiting for t1 time according to generation of a random number, for example, and occupies the corresponding channel if the corresponding channel can be occupied. In addition, the fixed RFID reader 130a performs a channel check after waiting for a time t2 which is a value larger than t1 according to generation of a random number, and thus prevents setting the channel occupied by the mobile RFID reader 110a as a use channel. Can be.

Alternatively, the wait may be configured to be performed after the use channel is determined through step S160.

That is, after the use channel is determined in step S160, a random number is generated, and after waiting for a time according to the random number, the user channel is again checked whether the use channel is occupied and access is made only to the use channel when the use channel is occupied.

Even in this case, it is possible to prevent the channel determined as the use channel from being occupied simultaneously by other RFID readers.

On the other hand, the channel check and the use channel determination through the step S150 or step S160 is performed for any channel in the RFID frequency band.

However, although the channel check is performed by determining that the RFID frequency band is occupied, there may not be a channel in a usable state for all channels in the RFID frequency band.

In this case, the RFID reader may continue to transmit a signal to the beacon channel through step S130 to perform the inspection until a usable channel comes out while occupying the RFID frequency band.

Alternatively, the signal transmission to the beacon channel of step S130 may be stopped without performing the continuous occupancy, and then the test may be started by checking the beacon channel again after a predetermined time has elapsed.

While the above-described determination of the use channel is performed for any channel in the RFID frequency band, a configuration may be performed for a plurality of channels in the RFID frequency band and selecting and determining the use channel among the plurality of channels.

In other words, the signal levels of the plurality of channels are checked and a channel whose signal level is equal to or less than the above-described channel usage threshold is set as the use channel. In this case, preferably, the channel having the smallest signal level among the plurality of channels may be determined as the use channel.

Even in this case, waiting may be performed for any of the above-described times before the channel check or after the use channel is determined to prevent interference or collision.

In addition, the determining step of the use channel based on the aforementioned channel usage threshold or the possible collision threshold or the collision avoidance threshold may also be applied.

The present invention also provides a computer-readable recording medium storing a program for realizing each step of the channel access method of the RFID reader according to the present invention described above.

However, a detailed description of such a computer-readable recording medium will be omitted since it overlaps with the channel access method of the RFID reader according to the present invention described with reference to FIGS.

Although the configuration of the present invention has been described in detail, it is only for illustrating the present invention, and the protection scope of the present invention is not limited thereto, and the protection scope of the present invention is defined through the description of the claims.

As described above, according to the present invention, by checking the beacon channel indicating whether the RFID frequency band is occupied without performing the band LBT, it is possible to easily determine whether the RFID frequency band can be occupied and simultaneously occupy the channel through the channel inspection. By reducing the possibility of occurrence of interference or collision between the RFID readers can reduce the recognition rate of the RFID reader and malfunction of the RFID system.

Claims (17)

(a) inspecting a beacon channel set within the RFID frequency band; (b) determining whether to occupy the RFID frequency band based on the beacon channel test result; (c) transmitting a signal to the beacon channel when the RFID frequency band is occupied Channel access method of the RFID reader comprising a. The method of claim 1, (d) if the RFID frequency band is not occupied, waiting for an arbitrary time and then jumping to step (a) Channel access method of the RFID reader further comprising. The method of claim 1, And the beacon channel is any channel predetermined in the RFID frequency band. According to claim 1, wherein step (a) is, (a-1) checking the signal level of the beacon channel Channel access method of the RFID reader that includes. The method of claim 4, wherein step (b) comprises: (b-1) determining that the RFID frequency band can be occupied if the signal level is less than or equal to a predetermined band usage threshold; and determining that the RFID frequency band is not occupied if the signal level is greater than the band usage threshold. Channel access method of the RFID reader that includes. The method of claim 1, wherein after step (c), (e) checking whether any channel in the RFID frequency band is occupied, (f) if the channel is not occupied, determining the channel as a use channel Channel access method of the RFID reader that includes. The method of claim 6, wherein, prior to step (e), (g) waiting for any time Channel access method of the RFID reader further comprising. The method of claim 6, wherein after step (f), (h) waiting for any time; (i) checking that the usage channel is occupied, (j) accessing the use channel if the use channel is not occupied Channel access method of the RFID reader further comprising. The method of claim 6, The step (e) comprises: (e-1) checking the signal level of the arbitrary channel To include, The step (f) comprises: (f-1) determining the arbitrary channel as the use channel when the signal level of the any channel is equal to or less than a predetermined channel use threshold. Channel access method of the RFID reader that includes. The method of claim 6, Step (a), (a-1) checking the signal level of the beacon channel To include, The step (e) comprises: (e-1) checking the signal level of the arbitrary channel To include, The step (f) may include (f-2) the arbitrary channel only when the magnitude of the signal level of the arbitrary channel is less than or equal to a predetermined collision avoidance threshold when the signal level of the beacon channel is greater than a predetermined collision possibility threshold. Determining as the use channel Channel access method of the RFID reader that includes. The method of claim 1, wherein after step (c), (k) examining a plurality of channels in the RFID frequency band; (l) determining a usage channel among the plurality of channels Channel access method of the RFID reader further comprising. The method of claim 11, wherein, prior to step (k), (m) waiting for an arbitrary time Channel access method of the RFID reader further comprising. The method of claim 11, wherein after step (l), (n) waiting for any time; (o) checking that the usage channel is occupied, (p) connecting to the use channel if the use channel is not occupied Channel access method of the RFID reader further comprising. The method of claim 11, The step (k) comprises: (k-1) checking signal levels of the plurality of channels To include, The step (l) may include (l-1) determining a channel having the signal level below a predetermined channel use threshold value among the plurality of channels as the use channel. Channel access method of the RFID reader that includes. The method of claim 14, In the step (l-1), (l-2) determining the channel having the smallest signal level among the plurality of channels as the use channel. Channel access method of the RFID reader that includes. The method of claim 14, Step (a), (a-1) checking the signal level of the beacon channel To include, The step (k) comprises: (k-1) checking signal levels of the plurality of channels To include, In step (l), when the signal level of the beacon channel is greater than a predetermined collision possibility threshold, the signal level of the plurality of channels has a minimum value which is smaller than or equal to a predetermined collision avoidance threshold. Determining a channel as the use channel Channel access method of the RFID reader that includes. A computer-readable recording medium having recorded thereon a program for realizing each step of the channel access method of the RFID reader according to any one of claims 1 to 16.

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