Ambient backscatter communication method and system using multiple tags and intelligent reflecting surface

Abstract

An ambient backscatter communication method and system using multiple tags and an intelligent reflecting surface (IRS) are disclosed. The ambient backscatter communication method may comprise the steps of: controlling phase values of reflective elements of a first IRS located between an RF source and tags and phase values of reflective elements of a second IRS located between the tags and a reader in an ambient backscatter communication system; driving the first IRS and the second IRS in which the respective phase values of the reflective elements have been controlled; identifying the performance of each of the tags by means of the driven first IRS and second IRS; selecting a tag with the highest performance from among the tags; receiving a signal including tag information through the selected tag; and estimating the tag information by using the threshold value of the selected tag in the received signal.

Description

Ambient backscatter communication method and system using multiple tags and intelligent reflective surfaces

[0001] The present invention relates to a method and device for ambient backscattering communication, and more particularly, to a method and system for ambient backscattering communication including multiple tags and an intelligent reflective surface.

[0002] As interest in the Internet of Things (IoT) grows, research is being conducted to secure and improve frequency bands for wireless communications in large-scale IoT networks. Ambient Backscatter Communication (ABC) systems have been developed to address this issue.

[0003] Ambient backscatter communication system is an ultra-low-power communication technology that transmits information by adjusting the reflection or absorption of radiated radio signals existing in the surroundings through impedance matching of the antenna without directly generating a transmission signal.

[0004] Since the peripheral backscatter communication system is an ultra-low-power communication technology, there is a need to improve communication efficiency.

[0005] Therefore, a method for improving the communication performance of a peripheral backscatter communication system is required.

[0006] The present invention provides a method and device for peripheral backscattering communication that improves communication performance by selecting a tag having the highest transmission performance among a plurality of tags, and amplifying a wireless signal transmitted to the selected tag and a wireless signal output from the selected tag using an intelligent reflecting surface (IRS).

[0007] According to one embodiment of the present invention, an ambient backscattering communication method may include the steps of controlling phase values ​​of reflective elements of a first IRS located between an RF source and tags in an ambient backscattering communication system and phase values ​​of reflective elements of a second IRS located between the tags and a reader; driving the first IRS and the second IRS, each of which has a controlled phase value of the reflective elements; identifying performance of each of the tags by the driven first IRS and the second IRS; selecting a tag having the highest performance among the tags; receiving a signal including tag information through the selected tag; and estimating the tag information by using a threshold value of the selected tag in the received signal.

[0008] A peripheral backscatter communication method according to one embodiment of the present invention further includes a step of selecting a tag among the tags whose threshold value has not been determined, transmitting 1 bit to the selected tag, and transmitting 0 bit to the remaining tags to determine a threshold value of the selected tag, and the step of determining the threshold value may be repeatedly performed until the threshold value of each of the tags is determined.

[0009] The step of controlling the phase value of the reflective element of the peripheral backscattering communication method according to one embodiment of the present invention may include the steps of: estimating channel state information of each channel used in the peripheral backscattering communication system; determining an optimal phase shift value of the first IRS based on the channel state information; controlling the phase value of the reflective element of the first IRS to correspond to the optimal phase shift value of the first IRS; determining an optimal phase shift value of the second IRS based on the channel state information; and controlling the phase value of the reflective element of the second IRS to correspond to the optimal phase shift value of the second IRS.

[0010] The step of determining the optimal phase shift value of the first IRS in the peripheral backscattering communication method according to one embodiment of the present invention may determine the optimal phase shift value of the first IRS using the phase of the channel between each of the tags and the RF source, the phase of the channel between the RF source and the first IRS, and the phase of the channel between each of the tags and the first IRS.

[0011] The step of determining the optimal phase shift value of the second IRS in the peripheral backscattering communication method according to one embodiment of the present invention may determine the optimal phase shift value of the second IRS using the phase of the channel between each of the tags and the reader, the phase of the channel between each of the tags and the second IRS, and the phase of the channel between the second IRS and the reader.

[0012] In the step of identifying the performance of each tag in the peripheral backscattering communication method according to one embodiment of the present invention, the performance of each tag can be determined using a radio signal received by each tag from the RF source, a phase of a channel between the RF source and the first IRS, a phase value of a reflective element of the first IRS, a radio signal adjusted by the first IRS, a radio signal output from each tag, a phase of a channel between each tag and the second IRS, a phase value of a reflective element of the second IRS, and a radio signal adjusted by the second IRS.

[0013] A method for ambient backscattering communication according to one embodiment of the present invention may include the steps of: controlling a phase value of a reflective element of an IRS located between an RF source and tags in an ambient backscattering communication system; driving the IRS according to the phase value of the reflective element; identifying performance of each of the tags by the driven IRS; selecting a tag having the highest performance among the tags; receiving a signal including tag information through the selected tag; and estimating the tag information by using a threshold value of the selected tag in the received signal.

[0014] A peripheral backscatter communication method according to one embodiment of the present invention further includes a step of selecting a tag among the tags whose threshold value has not been determined, transmitting 1 bit to the selected tag, and transmitting 0 bit to the remaining tags to determine a threshold value of the selected tag, and the step of determining the threshold value may be repeatedly performed until the threshold value of each of the tags is determined.

[0015] The step of controlling the phase value of the reflective element of the peripheral backscattering communication method according to one embodiment of the present invention may include the step of estimating channel state information of each channel used in the peripheral backscattering communication system; the step of determining an optimal phase shift value of the IRS based on the channel state information; and the step of controlling the phase value of the reflective element of the IRS to correspond to the optimal phase shift value of the IRS.

[0016] The step of determining the optimal phase shift value of the IRS in the peripheral backscattering communication method according to one embodiment of the present invention may determine the optimal phase shift value of the IRS using the phase of the channel between each of the tags and the RF source, the phase of the channel between the RF source and the IRS, and the phase of the channel between each of the tags and the IRS.

[0017] The step of identifying the performance of each tag in the peripheral backscattering communication method according to one embodiment of the present invention may determine the performance of each tag by using the phase of the channel between each tag and the RF source, the phase of the channel between the RF source and the first IRS, the phase value of the reflective element of the first IRS, the phase of the channel between each tag and the first IRS, and the phase of the channel between each tag and the reader.

[0018] According to one embodiment of the present invention, an ambient backscatter communication system includes: a first IRS positioned between an RF source and tags; tags that output a signal including tag information using a signal received from the RF source and the first IRS; a second IRS positioned between the tags and a reader; and a reader that estimates the tag information from a signal received from the tags and the second IRS, wherein the reader controls phase values ​​of reflective elements of the first IRS and the second IRS, drives the first IRS and the second IRS whose respective phase values ​​of the reflective elements are controlled, identifies performance of each of the tags by the driven first IRS and the second IRS, selects a tag having the highest performance among the tags, receives a signal including tag information through the selected tag, and estimates the tag information by using a threshold value of the selected tag in the received signal.

[0019] The reader of the peripheral backscatter communication system according to one embodiment of the present invention can select a tag among the tags for which a threshold value has not been determined, transmit 1 bit to the selected tag, and transmit 0 bit to the remaining tags to determine the threshold value of the selected tag.

[0020] The leader of the peripheral backscattering communication system according to one embodiment of the present invention estimates channel state information of each channel used in the peripheral backscattering communication system, determines an optimal phase shift value of the first IRS based on the channel state information, controls a phase value of a reflective element of the first IRS to correspond to the optimal phase shift value of the first IRS, determines an optimal phase shift value of the second IRS based on the channel state information, and controls a phase value of a reflective element of the second IRS to correspond to the optimal phase shift value of the second IRS.

[0021] The reader of the peripheral backscatter communication system according to one embodiment of the present invention can determine an optimal phase shift value of the first IRS using the phase of the channel between each of the tags and the RF source, the phase of the channel between the RF source and the first IRS, and the phase of the channel between each of the tags and the first IRS.

[0022] The reader of the peripheral backscatter communication system according to one embodiment of the present invention can determine an optimal phase shift value of the second IRS using the phase of the channel between each of the tags and the reader, the phase of the channel between each of the tags and the second IRS, and the phase of the channel between the second IRS and the reader.

[0023] The reader of the peripheral backscatter communication system according to one embodiment of the present invention can determine the performance of each tag by using a radio signal received by each tag from the RF source, a phase of a channel between the RF source and the first IRS, a phase value of a reflective element of the first IRS, a radio signal adjusted by the first IRS, a radio signal output from each tag, a phase of a channel between each tag and the second IRS, a phase value of a reflective element of the second IRS, and a radio signal adjusted by the second IRS.

[0024] According to one embodiment of the present invention, communication performance can be improved by selecting a tag having the highest transmission performance among a plurality of tags in a peripheral backscatter communication system, and amplifying a wireless signal transmitted to the selected tag and a wireless signal output from the selected tag by an IRS.

[0025] FIG. 1 is a diagram illustrating a peripheral backscatter communication system according to a first embodiment of the present invention.

[0026] FIG. 2 is a frame structure of a peripheral backscatter communication system according to one embodiment of the present invention.

[0027] FIG. 3 is a diagram illustrating a peripheral backscattering communication system according to a second embodiment of the present invention.

[0028] FIG. 4 is an example of performance change in response to SNR change of a peripheral backscatter communication system according to one embodiment of the present invention.

[0029] FIG. 5 is an example of performance changes in response to changes in the number of tags in a peripheral backscatter communication system according to one embodiment of the present invention.

[0030] FIG. 6 is an example of performance changes in response to changes in the number of reflective elements of an IRS of a peripheral backscatter communication system according to one embodiment of the present invention.

[0031] FIG. 7 is a flowchart illustrating a peripheral backscattering communication method according to a first embodiment of the present invention.

[0032] FIG. 8 is a flowchart illustrating a peripheral backscattering communication method according to a second embodiment of the present invention.

[0033] Hereinafter, embodiments are described in detail with reference to the attached drawings. However, the embodiments may be modified in various ways, and the scope of the patent application is not limited or restricted by these embodiments. It should be understood that all modifications, equivalents, or alternatives to the embodiments are included within the scope of the patent application.

[0034] The terms used in the examples are for illustrative purposes only and should not be construed as limiting. Singular expressions include plural expressions unless the context clearly dictates otherwise. In this specification, terms such as "comprise" or "have" are intended to indicate the presence of a feature, number, step, operation, component, part, or combination thereof described in the specification, but should be understood to not preclude the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0035] In addition, when describing with reference to the attached drawings, identical components will be assigned the same reference numerals regardless of the drawing numbers, and redundant descriptions thereof will be omitted. When describing embodiments, if a detailed description of a related known technology is judged to unnecessarily obscure the gist of the embodiment, the detailed description will be omitted.

[0036] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings.

[0037] FIG. 1 is a diagram illustrating a peripheral backscatter communication system according to a first embodiment of the present invention.

[0038] A peripheral backscatter communication system according to one embodiment of the present invention may include a first IRS (120), tags (130), a second IRS (140), and a reader (150) as illustrated in FIG. 1.

[0039] A peripheral backscatter communication system according to one embodiment of the present invention can receive information transmitted through the selected tag by the reader (150) by selecting one tag among the tags (130). For example, the tags (130) can be composed of 1 to K tags. In addition, the present specification describes a case where the tag selected by the reader (150) is the k-th tag, tag k. However, in some embodiments or for each frame, the tag selected by the reader (150) can be changed to one of tag 1 to tag k.

[0040] The RF source (110) can radiate a radio signal to the surrounding backscatter communication system. For example, the RF source (110) can be a base station, a relay antenna, or a broadcast antenna. In this case, the radio signal radiated by the RF source (110) can be used as an RF radio wave for power supply to each tag (130).

[0041] In addition, as shown in Fig. 1, among the wireless signals radiated from the RF source (110), the wireless signal received by the first IRS (120) can be defined as follows. And, among the wireless signals radiated from the RF source (110), the wireless signals received by the tags (130) are identified using the identification numbers of each tag 1 to tag k. , , . . . , can be defined as. In addition, among the wireless signals radiated from the RF source (110), the wireless signal received by the reader (150) can be defined as

[0042] The first IRS (Intelligent Reflecting Surfaces) (120) may be a device in which a plurality of reflective elements are arranged, and is positioned between the RF source (110) and the tags (130). In addition, the reflective elements of the first IRS (120) may have their phase values ​​controlled by the reader (150). In addition, the reflective elements of the first IRS (120) may adjust the radio signal radiated from the RF source (110) according to the controlled phase value and transmit the same to the tags (130). At this time, the controlled phase value is a radio signal received by tag k among the radio signals radiated from the RF source (110). so that it is amplified may be a parameter that adjusts the tag k. For example, to correspond to the tag k by the reflective elements of the first IRS (120). The adjusted wireless signal can be defined as

[0043] Each of the tags (130) may include an antenna or may be attached to a device including an antenna. In addition, each of the tags (130) may transmit tag information to the reader (150) by modulating a wireless signal by changing an impedance matching value of the antenna. The wireless signals modulated by each of the tags 1 to k to transmit information to the reader (150) are identified using the identification numbers of each of the tags 1 to k. , , . . . , can be defined as

[0044] Specifically, each of the tags (130) can transmit bit information of 0 or 1 to the reader (150) by adjusting the absorption or reflection of the wireless signal transmitted from the RF source (110) or the wireless signal amplified from the first IRS (120) through impedance matching or non-matching of the antenna. For example, each of the tags (130) may include a battery and may be a sensor node whose size is less than a reference value, or a low-power sensor node including an energy harvesting function. In addition, the tags (130) may be composed of sensor nodes of different types or may be composed of sensor nodes of the same type. In addition, the information transmitted by each of the tags (130) may include a sensor ID or information measured by the sensor.

[0045] The second IRS (140) is positioned between the tags (130) and the reader (150), and may be a device in which a plurality of reflective elements are arranged. In addition, the reflective elements of the second IRS (140) may have their phase values ​​controlled by the reader (150). In addition, the reflective elements of the second IRS (140) may adjust the wireless signals emitted from the tags (130) according to the controlled phase values ​​and transmit them to the reader (150).

[0046] At this time, the wireless signal received from tag k to the second IRS (140) can be defined as. And, the controlled phase value is a wireless signal transmitted from tag k to the reader (150). so that it is amplified It may be a parameter that adjusts the tag k by the reflective elements of the second IRS (140). It may be a parameter that adjusts the tag k by the reflective elements of the second IRS (140). The wireless signal that has been adjusted can be defined as

[0047] The leader (150) can receive wireless signals radiated from the tags (130) and the second IRS (140), and estimate tag information transmitted by the tags (130) from the wireless signals.

[0048] The reader (150) can determine the threshold value of each tag (130). At this time, the reader (150) can select a tag among the tags (130) whose threshold value has not been determined, transmit 1 bit to the selected tag, and transmit 0 bit to the remaining tags to determine the threshold value of the selected tag. In addition, the reader (150) can determine the threshold value of each tag (130) by repeating the above process until the threshold value of each tag (130) is determined.

[0049] For example, the reader (150) can transmit N0 1-bits to the k-th tag and transmit 0-bits to the remaining tags (130) except for the k-th tag. At this time, N0 can be the number of bits that the reader (150) transmits to the k-th tag in the preamble section. In addition, the reader (150) can determine the threshold value of the tags that transmitted 0-bits. Determined according to mathematical formula 1, the threshold value of the kth tag that transmitted 1 bit can be determined according to mathematical formula 2.

[0050] [Mathematical Formula 1]

[0051]

[0052] [Equation 2]

[0053]

[0054] At this time, the threshold value can be the average reception power when each tag transmits a bit. That is, the threshold value is the average reception power of tags that transmitted 0 bits, and the threshold may be the average reception power of the kth tag that transmitted 1 bit. Also, 1 in indicates a tag that transmitted 1 bit. Replace with can be expressed as . At this time, Is It may be the average reception power when the corresponding tag transmits 1 bit.

[0055] Next, the reader (150) can control the phase value of the reflective element of the first IRS (120) and the phase value of the reflective element of the second IRS (140). Specifically, the reader (150) can estimate channel status information (CSI) of each channel used in the surrounding backscatter communication system. At this time, the reader (150) can sequentially estimate the channel value for the preset bit pattern for each of the h channel and the g channel. For example, the reader (150) can determine the channel status information by estimating the channel values ​​of the h channel and the g channel using at least one of various existing channel estimation methods.

[0056] The leader (150) can determine the optimal phase shift value of the first IRS (120) based on the estimated channel state information. At this time, the leader (150) determines the phase of the channel between each tag (130) and the RF source (110). , the phase of the channel between the RF source (110) and the first IRS (120). , and the phase of the channel between each of the tags (130) and the first IRS (120). The optimal phase shift value of the first IRS (120) can be determined using Equation 3. For example, the leader (150) can determine the optimal phase shift value of the first IRS (120) using Equation 3. can decide.

[0057] [Equation 3]

[0058]

[0059] The leader (150) is the optimal phase shift value of the first IRS (120). The phase values ​​of the reflective elements of the first IRS (120) to correspond to can be controlled. At this time, In , the superscript * is a symbol indicating the optimal value among the phase values, and the subscript n may be a value corresponding to each of the N reflection elements included in the first IRS (120). For example, Since is a phase value corresponding to the first reflection element among the N reflection elements included in the first IRS (120), the leader (150) is the first reflection element of the first IRS (120). The phase value of the first reflective element can be controlled to have a value that is the same as or similar to a certain range or more. In addition, is a vector phase value of the first IRS (120) including N reflective elements, and can be determined according to the phase value of each of the N reflective elements.

[0060] The leader (150) can determine the optimal phase shift value of the second IRS (140) based on the estimated channel state information. At this time, the leader (150) determines the phase of the channel between each tag (130) and the leader (150). , the phase of the channel between each of the tags (130) and the second IRS (140). , and the phase of the channel between the second IRS (140) and the leader (150). The optimal phase shift value of the second IRS (140) using can decide.

[0061] [Equation 4]

[0062]

[0063] The leader (150) is the optimal phase shift value of the second IRS (140). The phase values ​​of the reflective elements of the second IRS (140) to correspond to can control.

[0064] Leader (150) The first IRS (120) and the phase values ​​of the reflective elements are controlled according to According to this, the second IRS (140) can be driven with the phase values ​​of the reflective elements controlled.

[0065] Next, the reader (150) can identify the performance of each tag (130) by the driven first IRS and second IRS. At this time, the reader (150) can identify the performance of each tag (130) by the wireless signal received from the RF source (110). , phase of the channel between the RF source (110) and the first IRS (120), phase value of the reflection element of the first IRS (120) , radio signal adjusted in the first IRS (120) , wireless signals output from tags (130) , the phase of the channel between each of the tags (130) and the second IRS (140), the phase value of the reflection element of the second IRS (140) and the radio signal adjusted in the second IRS (140) The performance of each tag (130) can be determined using .

[0066] Next, the leader (150) can select the tag with the highest performance among the tags (130). For example, the leader (150) can select the tag with the highest performance among the tags (130) using mathematical expression 5. You can choose.

[0067] [Equation 5]

[0068]

[0069] At this time, is a diagonal matrix that is matrixized to perform a multiplication operation with the vector channel g, and is the phase value of the reflection element of the first IRS (120). The optimal vector phase value among them can be generated by placing it on the diagonal elements. In addition, Is and a column vector so that multiplication operations can be performed with vector channels g. It may be a row vector generated by transforming it into a transpose.

[0070] Next, the leader (150) transmits a wireless signal containing tag information through the selected tag. can receive. For example, if the tag selected by the leader (150) is tag k, the first IRS (120) corresponds to tag k. The adjusted wireless signal can be transmitted to tag k. At this time, the wireless signal received by tag k from the RF source (110) is a wireless signal can be amplified by the radio signal. On the other hand, the radio signals received by each of the other tags are radio signals. may not be amplified by

[0071] And, tag k modulates the received wireless signals, thereby generating a wireless signal containing tag information, which is information measured by tag k. and As described above, the tag k receives a wireless signal from the RF source (110). Since the wireless signals received by each of the other tags are amplified, the wireless signal output by tag k may also have a higher output strength and quality than the wireless signals output by the other tags.

[0072] wireless signal The second IRS (140) that received the tag corresponds to the tag k. The adjusted wireless signal can be transmitted to the leader (150). At this time, the wireless signal transmitted by tag k is a wireless signal It can be amplified and received by the leader (150).

[0073] That is, the wireless signal of the RF source (110) that tag k uses for power to output a wireless signal containing tag information and the wireless signal output from tag k are amplified according to the wireless signal reflected from the first IRS (120) and the second IRS (140), respectively, so that the wireless signal transmitted by tag k The strength or quality of the wireless signal output from other tags can be doubled.

[0074] For example, a wireless signal received from a tag (tag k) selected by the leader (150) can be defined as in mathematical formula 6.

[0075] [Equation 6]

[0076]

[0077] Finally, the reader (150) can estimate the original tag information B(n) generated from the tag by using the threshold value of the selected tag in the received signal. At this time, B(n) may be the bit output by the tag in the nth time slot. For example, the reader (150) can estimate the tag information as in Equation 7. can be estimated.

[0078] [Equation 7]

[0079]

[0080] may be tag information estimated from the signal received by the leader (150). And, the leader (150) estimates the average reception power of the received signal. The value is the threshold Value and By comparing B(n) to estimate whether it is 0 or 1, and the result of the estimate is It can be printed as .

[0081] A peripheral backscatter communication system according to one embodiment of the present invention can improve communication performance by selecting a tag with the highest transmission performance among a plurality of tags, and amplifying a wireless signal transmitted to the selected tag and a wireless signal output from the selected tag with an IRS.

[0082] FIG. 2 is a frame structure of a peripheral backscatter communication system according to one embodiment of the present invention.

[0083] The frame structure of a peripheral backscatter communication system according to one embodiment of the present invention may be composed of one preamble (210) and a plurality of frames (220), as illustrated in FIG. 2.

[0084] In the preamble (210), the reader (150) can determine the threshold value of each tag by sequentially transmitting 1 bit to each tag 1 to tag K and 0 bit to the remaining tags. For example, in the 0 section of the preamble (210), the reader (150) can determine the threshold value of tag 1 by transmitting 1 bit to tag 1 and 0 bit to the remaining tags except for tag 1. In addition, in the 1 section of the preamble (210), the reader (150) can determine the threshold value of tag 2 by transmitting 1 bit to tag 2 and 0 bit to the remaining tags except for tag 2. In addition, in the K-1 section of the preamble (210), the reader (150) can determine the threshold value of tag K by transmitting 1 bit to tag 1 and 0 bit to the remaining tags except for tag K.

[0085] The reader (150) can perform channel estimation (221), tag selection (222), and tag information transmission (223) processes in each frame (220). Specifically, in the channel estimation (221) process, the reader (150) can estimate channel state information and control the phase values ​​of the first IRS (120) and the second IRS (140) based on the estimated channel state information. In the tag selection (222) process, the reader (150) can identify the performance of each tag (130) and select the tag with the highest performance. In the tag information transmission (223) process, the reader (150) can receive tag information from the selected tag and estimate original tag information by using the threshold values ​​of each tag determined in the preamble (210) to the received tag information.

[0086] The ambient backscattering communication system according to the present invention may include one IRS as illustrated in FIG. 3. In FIG. 3, the IRS (320) is positioned between the RF source (310) and the tags (300), but in some embodiments, the IRS (320) may be positioned between the tags (300) and the reader (340). In addition, in the ambient backscattering communication system illustrated in FIG. 1, when the second IRS (140) fails, the reader (150) may operate like the reader (340) illustrated in FIG. 3. In addition, in the ambient backscattering communication system illustrated in FIG. 1, when the first IRS (120) fails, the reader (150) may operate like the reader of the embodiment in which the IRS (320) is positioned between the tags (300) and the reader (340).

[0087] The RF source (310), IRS (320), and tags (330) have the same configuration as the RF source (110), first IRS (120), and tags (330) of FIG. 1, so a detailed description thereof will be omitted.

[0088] The reader (340) can determine the threshold value of each tag (330). At this time, the reader (340) can select a tag among the tags (330) whose threshold value has not been determined, transmit 1 bit to the selected tag, and transmit 0 bit to the remaining tags to determine the threshold value of the selected tag. In addition, the reader (340) can determine the threshold value of each tag (330) by repeating the above process until the threshold value of each tag (330) is determined.

[0089] For example, the leader (340) can transmit N0 1-bits to the k-th tag and transmit 0-bits to the remaining tags (330) except for the k-th tag. Then, the leader (340) can determine the threshold value of the tags that transmitted 0-bits. Determined according to mathematical formula 1, the threshold value of the kth tag that transmitted 1 bit can be determined according to mathematical formula 2.

[0090] Next, the leader (340) can control the phase value of the reflective element of the IRS (320). Specifically, the leader (340) can estimate the channel status information (CSI) of each channel used in the surrounding backscatter communication system.

[0091] The leader (340) can determine the optimal phase shift value of the IRS (320) based on the estimated channel state information. At this time, the leader (340) determines the phase of the channel between each tag (330) and the RF source (310). , the phase of the channel between the RF source (310) and the IRS (320). and the phase of the channel between each of the tags (330) and the IRS (320). The optimal phase shift value of the IRS (320) can be determined using Equation 3. For example, the leader (340) can determine the optimal phase shift value of the IRS (320) using Equation 3. can decide.

[0092] The leader (340) is the optimal phase shift value of IRS (320). The phase values ​​of the reflective elements of IRS (320) to correspond to can control.

[0093] Leader (340) According to this, the phase value of the reflective elements can be controlled to drive the IRS (320).

[0094] Next, the reader (340) can identify the performance of each tag (330) by the driven IRS (320). At this time, the reader (340) can identify the performance of each tag (330) by the wireless signal received from the RF source (310). , phase of the channel between the RF source (310) and the IRS (320), phase value of the reflection element of the IRS (320) , radio signal adjusted by IRS (320) , wireless signals output from tags (330) The performance of each tag (330) can be determined using .

[0095] Next, the leader (340) can select the tag with the highest performance among the tags (330). For example, the leader (340) can select the tag with the highest performance among the tags (330) using Equation 8. You can choose.

[0096] [Equation 8]

[0097]

[0098] Next, the leader (340) transmits a wireless signal containing tag information through the selected tag. can receive. For example, if the tag selected by the reader (340) is tag k, the IRS (320) can receive the tag corresponding to tag k. The adjusted wireless signal can be transmitted to tag k. At this time, the wireless signal received by tag k from the RF source (310) is a wireless signal can be amplified by the radio signal. On the other hand, the radio signals received by each of the other tags are radio signals. may not be amplified by

[0099] And, tag k modulates the received wireless signals, thereby generating a wireless signal containing tag information, which is information measured by tag k. As described above, the tag k receives a wireless signal from the RF source (310). Since the wireless signals received by each of the other tags are amplified, the wireless signal output by tag k and received by the reader (340) It may be a wireless signal with higher output strength and quality than the wireless signals output by other tags. For example, a wireless signal received from a tag (tag k) selected by the reader (340) can be defined as in mathematical formula 9.

[0100] [Equation 9]

[0101]

[0102] Finally, the leader (340) can estimate tag information using the threshold value of the selected tag. For example, the leader (340) can estimate tag information using Equation 7. Value and, Value and Compare tag information It can be estimated.

[0103] FIG. 4 is an example of performance change in response to SNR change of a peripheral backscatter communication system according to one embodiment of the present invention.

[0104] Graph (410) can represent a change in the average bit error rate (BER) with respect to a change in SNR. According to graph (410), the average BER performance of the ambient backscattering communication system (402, 403) that selects the tag with the highest transmission performance may be higher than that of the ambient backscattering communication system (401) that randomly selects tags. In addition, among the ambient backscattering communication systems that select the tag with the highest transmission performance, the average BER performance of the ambient backscattering communication system (403) that determines an optimal phase shift value according to an embodiment of the present invention and determines the phase value of the IRS according to the optimal phase shift value may be higher than that of the ambient backscattering communication system (402) that randomly determines the phase value of the IRS.

[0105] Graph (420) can represent a change in an average data rate (achievable rate) with respect to a change in SNR. According to graph (420), the average data rate performance of the ambient backscattering communication system (402, 403) that selects the tag with the highest transmission performance can be higher than that of the ambient backscattering communication system (401) that randomly selects tags. In addition, among the ambient backscattering communication systems that select the tag with the highest transmission performance, the average data rate performance of the ambient backscattering communication system (403) that determines an optimal phase shift value according to an embodiment of the present invention and determines the phase value of the IRS according to the optimal phase shift value can be higher than that of the ambient backscattering communication system (402) that randomly determines the phase value of the IRS.

[0106] FIG. 5 is an example of performance changes in response to changes in the number of tags in a peripheral backscatter communication system according to one embodiment of the present invention.

[0107] Graph (510) may represent a change in the average bit error rate with respect to a change in the number of tags included in the peripheral backscattering communication system. In addition, graph (520) may represent a change in the average data transmission rate with respect to a change in the number of tags included in the peripheral backscattering communication system. As illustrated in FIG. 5, as the number of tags included in the peripheral backscattering communication system increases, the average bit error rate performance and the average data transmission rate performance may also increase. However, when the number of tags is up to 5 or 10, the degree of increase in the average bit error rate performance and the average data transmission rate performance with respect to the increase in the number of tags is high, but when the number of tags exceeds 10, the degree of increase in the average bit error rate performance and the average data transmission rate performance with respect to the increase in the number of tags may be low.

[0108] Additionally, an ambient backscattering communication system (503, 505) including an IRS having 64 reflective elements can exhibit optimal average bit error rate performance and average data transmission rate performance with a smaller number of tags than an ambient backscattering communication system (502, 504) including an IRS having 4 reflective elements.

[0109] And, compared to the peripheral backscattering communication system (502, 504) that randomly determines the phase value of the IRS, the peripheral backscattering communication system (503, 505) that determines the optimal phase shift value according to an embodiment of the present invention and determines the phase value of the IRS according to the optimal phase shift value can exhibit the optimal average bit error rate performance and average data transmission rate performance with a smaller number of tags.

[0110] Additionally, the ambient backscatter communication system (501) without IRS may have lower average bit error rate performance and average data transmission rate performance than the ambient backscatter communication systems (502, 503, 504, 505) with IRS.

[0111] FIG. 6 is an example of performance changes in response to changes in the number of reflective elements of an IRS of a peripheral backscatter communication system according to one embodiment of the present invention.

[0112] Graph (610) may represent a change in the average bit error rate with respect to a change in the number of reflective elements of an IRS included in a peripheral backscatter communication system. Additionally, graph (620) may represent a change in the average data transmission rate with respect to a change in the number of reflective elements of an IRS included in a peripheral backscatter communication system.

[0113] The peripheral backscattering communication system (601) that randomly determines the phase value of the IRS may not have changes in the average bit error rate performance and the average data transmission rate performance even if the number of reflection elements of the IRS changes.

[0114] On the other hand, in accordance with one embodiment of the present invention, a peripheral backscattering communication system (602) that determines an optimal phase shift value and determines a phase value of an IRS according to the optimal phase shift value can increase the average bit error rate performance and the average data transmission rate performance as the number of reflective elements of the IRS increases, as illustrated in FIG. 6.

[0115] FIG. 7 is a flowchart illustrating a peripheral backscattering communication method according to a first embodiment of the present invention.

[0116] In step (710), the reader (150) can determine the threshold value of each tag (130). At this time, the reader (150) can select a tag among the tags (130) whose threshold value has not been determined, transmit 1 bit to the selected tag, and transmit 0 bit to the remaining tags to determine the threshold value of the selected tag. In addition, the reader (150) can determine the threshold value of each tag (130) by repeating the above process until the threshold value of each tag (130) is determined.

[0117] In step (720), the leader (150) can estimate channel status information (CSI) of each channel used in the surrounding backscatter communication system.

[0118] In step (730), the reader (150) can determine the optimal phase shift value of the first IRS (120) based on the channel state information estimated in step (720). At this time, the reader (150) can determine the optimal phase shift value of the first IRS (120) using the phase of the channel between each of the tags (130) and the RF source (110), the phase of the channel between the RF source (110) and the first IRS (120), and the phase of the channel between each of the tags (130) and the first IRS (120).

[0119] In step (740), the reader (150) can determine the optimal phase shift value of the second IRS (140) based on the channel state information estimated in step (720). At this time, the reader (150) can determine the optimal phase shift value of the second IRS (140) using the phase of the channel between each of the tags (130) and the reader (150), the phase of the channel between each of the tags (130) and the second IRS (140), and the phase of the channel between the second IRS (140) and the reader (150).

[0120] In step (750), the leader (150) sets the phase values ​​of the reflective elements of the first IRS (120) to correspond to the optimal phase shift value of the first IRS (120) determined in step (730). In addition, the leader (150) can control the phase values ​​of the reflective elements of the second IRS (140) to correspond to the optimal phase shift value of the second IRS (140) determined in step (740). can control.

[0121] At step (760), the leader (150) The first IRS (120) and the phase values ​​of the reflective elements are controlled according to According to this, the second IRS (140) whose phase values ​​of the reflective elements are controlled can be driven. Then, the reader (150) can identify the performance of each of the tags (130) by the driven first IRS and second IRS. At this time, the reader (150) can determine the performance of each of the tags (130) by using the radio signal that each of the tags (130) receives from the RF source (110), the phase of the channel between the RF source (110) and the first IRS (120), the phase value of the reflective element of the first IRS (120), the radio signal adjusted in the first IRS (120), the radio signal output from the tags (130), the phase of the channel between each of the tags (130) and the second IRS (140), the phase value of the reflective element of the second IRS (140), and the radio signal adjusted in the second IRS (140).

[0122] In step (770), the leader (150) can select the tag with the highest performance among the tags (130) whose performance was identified in step (760).

[0123] In step (780), the reader (150) can receive a wireless signal containing tag information through the tag selected in step (770). For example, if the tag selected by the reader (150) is tag k, the first IRS (120) can be configured to correspond to tag k. The adjusted wireless signal can be transmitted to tag k. At this time, the wireless signal received by tag k from the RF source (110) is a wireless signal can be amplified by. Then, tag k modulates the received wireless signals, thereby generating a wireless signal containing tag information, which is information measured by tag k. and can output wireless signals The second IRS (140) that received the tag corresponds to the tag k. The adjusted wireless signal can be transmitted to the leader (150). At this time, the wireless signal transmitted by tag k is a wireless signal It can be amplified and received by the leader (150).

[0124] In step (790), the leader (150) can estimate original tag information generated from the tag selected in step (770) by using the threshold value of the tag selected in step (770) in the wireless signal received in step (780).

[0125] FIG. 8 is a flowchart illustrating a peripheral backscattering communication method according to a second embodiment of the present invention.

[0126] In step (810), the reader (340) can determine the threshold value of each tag (330). At this time, the reader (340) can select a tag among the tags (330) whose threshold value has not been determined, transmit 1 bit to the selected tag, and transmit 0 bit to the remaining tags to determine the threshold value of the selected tag. In addition, the reader (340) can determine the threshold value of each tag (330) by repeating the above process until the threshold value of each tag (330) is determined.

[0127] In step (820), the leader (340) can estimate channel state information of each channel used in the surrounding backscatter communication system.

[0128] In step (830), the reader (340) can determine the optimal phase shift value of the IRS (320) based on the channel state information estimated in step (820). At this time, the reader (340) can determine the optimal phase shift value of the IRS (320) using the phase of the channel between each of the tags (330) and the RF source (310), the phase of the channel between the RF source (310) and the IRS (320), and the phase of the channel between each of the tags (330) and the IRS (320).

[0129] In step (840), the leader (340) sets the phase values ​​of the reflective elements of the IRS (320) to correspond to the optimal phase shift value of the IRS (320) determined in step (830). can control.

[0130] At step (850), the leader (340) According to the phase value of the reflective elements, the controlled IRS (320) can be driven. Next, the reader (340) can identify the performance of each tag (330) by the driven IRS (320). At this time, the reader (340) can determine the performance of each tag (330) by using the radio signal that each tag (330) receives from the RF source (310), the phase of the channel between the RF source (310) and the IRS (320), the phase value of the reflective element of the IRS (320), the radio signal adjusted in the IRS (320), and the radio signal output from the tags (330).

[0131] In step (860), the leader (340) can select the tag with the highest performance among the tags (330) whose performance was identified in step (850).

[0132] In step (870), the leader (340) transmits a wireless signal containing tag information through the tag selected in step (860). can receive. For example, if the tag selected by the reader (340) is tag k, the IRS (320) can receive the tag corresponding to tag k. The adjusted wireless signal can be transmitted to tag k. At this time, the wireless signal received by tag k from the RF source (310) is a wireless signal can be amplified by. Then, tag k modulates the received wireless signals, thereby generating a wireless signal containing tag information, which is information measured by tag k. can be printed.

[0133] In step (880), the leader (340) can estimate original tag information generated from the tag selected in step (860) by using the threshold value of the tag selected in step (860) in the wireless signal received in step (870).

[0134] The present invention can improve communication performance by selecting a tag having the highest transmission performance among a plurality of tags, and amplifying a wireless signal transmitted to the selected tag and a wireless signal output from the selected tag using an IRS.

[0135]

[0136] Meanwhile, the peripheral backscattering communication device or peripheral backscattering communication method based on the ignition data according to the present invention can be written as a program that can be executed on a computer and can be implemented in various recording media such as a magnetic storage medium, an optical reading medium, and a digital storage medium.

[0137] Implementations of the various technologies described herein may be implemented as digital electronic circuitry, or as computer hardware, firmware, software, or combinations thereof. Implementations may be implemented as a computer program product, for example, a computer program tangibly embodied in a machine-readable storage device (computer-readable medium), for processing by the operation of a data processing device, for example, a programmable processor, a computer, or multiple computers, or for controlling the operation thereof. A computer program, such as the computer program(s) described above, may be written in any form of programming language, including compiled or interpreted languages, and may be deployed in any form, including as a standalone program or as a module, component, subroutine, or other unit suitable for use in a computing environment. A computer program may be deployed to be processed on one computer or multiple computers at a single site, or to be distributed across multiple sites and interconnected by a communications network.

[0138] Processors suitable for processing a computer program include, for example, both general-purpose and special-purpose microprocessors, and any one or more processors of any type of digital computer. Typically, a processor will receive instructions and data from read-only memory or random-access memory, or both. Components of a computer may include at least one processor for executing instructions and one or more memory devices for storing instructions and data. Typically, a computer may include, or be coupled to receive data from, transmit data to, or both, one or more mass storage devices, such as magnetic, magneto-optical, or optical disks, for storing data. Information carriers suitable for embodying computer program instructions and data include, for example, semiconductor memory devices, magnetic media such as hard disks, floppy disks, and magnetic tapes, optical media such as compact disk read only memory (CD-ROM), digital video disks (DVD), magneto-optical media such as floptical disks, read only memory (ROM), random access memory (RAM), flash memory, erasable programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), etc. The processor and memory may be supplemented by, or included in, special purpose logic circuitry.

[0139] Additionally, the computer-readable medium may be any available medium that can be accessed by a computer, and may include all computer storage media.

[0140] While this specification contains details of a number of specific implementations, these should not be construed as limitations on the scope of any invention or what may be claimed, but rather as descriptions of features that may be unique to particular embodiments of particular inventions. Certain features described herein in the context of individual embodiments may also be implemented in combination in a single embodiment. Conversely, various features described in the context of a single embodiment may also be implemented in multiple embodiments, either individually or in any suitable subcombination. Furthermore, although features may operate in a particular combination and may initially be described as being claimed as such, one or more features from a claimed combination may in some cases be excluded from that combination, and the claimed combination may be modified into a subcombination or variation of a subcombination.

[0141] Likewise, while operations are depicted in the drawings in a particular order, this should not be construed as requiring that those operations be performed in the particular or sequential order depicted to achieve desired results, or that all depicted operations be performed. In certain instances, multitasking and parallel processing may be advantageous. Furthermore, the separation of the various device components of the embodiments described above should not be construed as requiring such separation in all embodiments, and it should be understood that the program components and devices described may generally be integrated together in a single software product or packaged into multiple software products.

[0142] Meanwhile, the embodiments of the present invention disclosed in this specification and drawings are merely specific examples presented to aid understanding and are not intended to limit the scope of the present invention. It will be apparent to those skilled in the art that other modifications based on the technical concepts of the present invention are possible in addition to the embodiments disclosed herein.

Claims

1. A step of controlling the phase values ​​of reflective elements of a first IRS located between an RF source and tags in a peripheral backscatter communication system and the phase values ​​of reflective elements of a second IRS located between the tags and a reader; A step of driving a first IRS and a second IRS, each of which has a controlled phase value of each reflective element; A step of identifying the performance of each of the tags by the driven first IRS and second IRS; A step of selecting the tag with the highest performance among the above tags; A step of receiving a signal containing tag information through a selected tag; and A step of estimating the tag information by using the threshold value of the selected tag in the received signal. A method of peripheral backscatter communication including:

2. In paragraph 1, A step of selecting a tag among the above tags whose threshold value has not been determined, transmitting 1 bit to the selected tag, and transmitting 0 bit to the remaining tags to determine the threshold value of the selected tag. Including more, The step of determining the above threshold is: A peripheral backscatter communication method that is repeatedly performed until the threshold values ​​of each of the above tags are all determined.

3. In paragraph 1, The step of controlling the phase value of the above reflective element is: A step of estimating channel state information of each channel used in a peripheral backscatter communication system; A step of determining an optimal phase shift value of the first IRS based on the channel state information; A step of controlling the phase value of the reflection element of the first IRS to correspond to the optimal phase shift value of the first IRS; A step of determining an optimal phase shift value of the second IRS based on the channel state information; and A step of controlling the phase value of the reflection element of the second IRS to correspond to the optimal phase shift value of the second IRS. A method of peripheral backscatter communication including:

4. In paragraph 3, The step of determining the optimal phase shift value of the first IRS is: A method for peripheral backscatter communication that determines an optimal phase shift value of the first IRS using the phase of the channel between each of the tags and the RF source, the phase of the channel between the RF source and the first IRS, and the phase of the channel between each of the tags and the first IRS.

5. In paragraph 3, The step of determining the optimal phase shift value of the second IRS is: A peripheral backscatter communication method for determining an optimal phase shift value of the second IRS using the phase of the channel between each of the tags and the reader, the phase of the channel between each of the tags and the second IRS, and the phase of the channel between the second IRS and the reader.

6. In paragraph 1, The step of identifying the performance of each of the above tags is: A method for peripheral backscatter communication that determines the performance of each tag by using a radio signal received by each tag from the RF source, a phase of a channel between the RF source and the first IRS, a phase value of a reflective element of the first IRS, a radio signal adjusted from the first IRS, a radio signal output from each tag, a phase of a channel between each tag and the second IRS, a phase value of a reflective element of the second IRS, and a radio signal adjusted from the second IRS.

7. A step of controlling the phase value of the reflective element of the IRS located between the RF source and tags in a peripheral backscatter communication system; A step of driving the IRS according to the phase value of the reflective element; A step of identifying the performance of each of the above tags by the driven IRS; A step of selecting the tag with the highest performance among the above tags; A step of receiving a signal containing tag information through a selected tag; and A step of estimating the tag information by using the threshold value of the selected tag in the received signal. A method of peripheral backscatter communication including:

8. In paragraph 7, A step of selecting a tag among the above tags whose threshold value has not been determined, transmitting 1 bit to the selected tag, and transmitting 0 bit to the remaining tags to determine the threshold value of the selected tag. Including more, The step of determining the above threshold is: A peripheral backscatter communication method that is repeatedly performed until the threshold values ​​of each of the above tags are all determined.

9. In paragraph 7, The step of controlling the phase value of the above reflective element is: A step of estimating channel state information of each channel used in a peripheral backscatter communication system; A step of determining an optimal phase shift value of the IRS based on the channel state information; and A step of controlling the phase value of the reflection element of the IRS to correspond to the optimal phase shift value of the IRS. A method of peripheral backscatter communication including: In paragraph 10.9, The step of determining the optimal phase shift value of the above IRS is: A method for peripheral backscatter communication that determines an optimal phase shift value of the IRS using the phase of the channel between each of the tags and the RF source, the phase of the channel between the RF source and the IRS, and the phase of the channel between each of the tags and the IRS.

11. In paragraph 7, The step of identifying the performance of each of the above tags is: A method for peripheral backscatter communication that determines the performance of each tag by using the phase of the channel between each of the tags and the RF source, the phase of the channel between the RF source and the IRS, the phase value of the reflective element of the IRS, the phase of the channel between each of the tags and the IRS, and the phase of the channel between each of the tags and the reader. 12.1st IRS located between RF source and tags; Tags that output a signal containing tag information using a signal received from an RF source and the first IRS; A second IRS located between the above tags and the reader; and A reader that estimates the tag information from the signals received from the above tags and the second IRS. Including, The above leader, Controlling the phase values ​​of the reflective elements of the first IRS and the second IRS, driving the first IRS and the second IRS whose phase values ​​of each of the reflective elements are controlled, and identifying the performance of each of the tags by the driven first IRS and the second IRS, A peripheral backscatter communication system that selects the tag with the highest performance among the above tags, receives a signal containing tag information through the selected tag, and estimates the tag information by using the threshold value of the selected tag in the received signal.

13. In paragraph 12, The above leader, A peripheral backscatter communication system that selects a tag among the above tags whose threshold value has not been determined, transmits 1 bit to the selected tag, and transmits 0 bit to the remaining tags to determine the threshold value of the selected tag.

14. In paragraph 12, The above leader, Estimate the channel state information of each channel used in the surrounding backscatter communication system, Determine the optimal phase shift value of the first IRS based on the channel state information, and control the phase value of the reflection element of the first IRS to correspond to the optimal phase shift value of the first IRS. A peripheral backscattering communication system that determines an optimal phase shift value of the second IRS based on the channel state information and controls the phase value of the reflective element of the second IRS to correspond to the optimal phase shift value of the second IRS.

15. In paragraph 14, The above leader, A peripheral backscatter communication system that determines an optimal phase shift value of the first IRS using the phase of the channel between each of the tags and the RF source, the phase of the channel between the RF source and the first IRS, and the phase of the channel between each of the tags and the first IRS.

16. In paragraph 14, The above leader, A peripheral backscatter communication system that determines an optimal phase shift value of the second IRS using the phase of the channel between each of the tags and the reader, the phase of the channel between each of the tags and the second IRS, and the phase of the channel between the second IRS and the reader.

17. In paragraph 12, The above leader, A peripheral backscatter communication system that determines the performance of each tag by using a radio signal received by each tag from the RF source, a phase of a channel between the RF source and the first IRS, a phase value of a reflective element of the first IRS, a radio signal adjusted from the first IRS, a radio signal output from each tag, a phase of a channel between each tag and the second IRS, a phase value of a reflective element of the second IRS, and a radio signal adjusted from the second IRS.

Images