KR20230110128A - Apparatus and method for estimating channel using multi-cyclic shift separation technique - Google Patents

Abstract

This document relates to an apparatus and method for estimating a channel using a multi-cyclic shift separation technique, comprising: a fast Fourier transform unit for converting a received pilot signal into a frequency domain signal through fast Fourier transform; a reference signal generator for generating a reference signal; a decorrelator for obtaining a decorrelated signal by multiplying the frequency domain signal by the reference signal; a phase rotation estimator for estimating a phase rotation value through inverse discrete Fourier transform on the decorrelated signal; and a channel transformation matrix processing unit for estimating a channel from a first subcarrier by multiplying the decorrelated signal by the channel transformation matrix.

Description

Channel estimation apparatus and method using multi-cyclic shift separation technique

The following embodiments relate to an apparatus and method for estimating a channel in which interference of multi-cyclic shift is removed by reflecting time offset information.

A reference signal used in the uplink of long term evolution (LTE) / new radio (NR) uses the same time and frequency resources by different user elements (UEs) by cyclic shift (CS) and simultaneously uses them. In this case, the user's channel can be estimated only when interference between these cyclic shifts is removed.

When a signal in which several cyclic shifts overlap is received, interference between cyclic shifts occurs, but interference between cyclic shifts can be removed through a simple moving average (MA) by using the property that cyclic shifts are orthogonal to each other.

However, removing interference between cyclic shifts using moving average is a possible method when there is no time offset. In the case of a channel with a time offset, it is difficult to remove interference between cyclic shifts with only simple moving average.

According to various embodiments disclosed in this document, it relates to an apparatus and method for channel estimation using a multi-cyclic shift separation technique reflecting time offset information, which utilizes the characteristics of a cyclic shift signal to transform a known Vandermonde matrix so that an inverse matrix can be used, and through this, a channel estimation apparatus having a closed-form solution can be proposed.

An apparatus for estimating a channel according to an exemplary embodiment includes: a fast Fourier transform unit converting a received pilot signal into a signal in a frequency domain through fast Fourier transform; a reference signal generator for generating a reference signal; a decorrelation unit that obtains a decorrelated signal by performing decorrelation by multiplying the signal in the frequency domain by the reference signal; a phase rotation estimation unit estimating a phase rotation value through inverse discrete Fourier transform of the decorrelated signal; and a channel transformation matrix processing unit for determining a channel transformation matrix using the phase rotation value and estimating a channel from a first subcarrier by multiplying the decorrelated signal by the channel transformation matrix.

An apparatus for estimating a channel according to an exemplary embodiment includes: a fast Fourier transform unit converting a received pilot signal into a signal in a frequency domain through fast Fourier transform; a reference signal generator for generating a reference signal; a decorrelation unit that obtains a decorrelated signal by performing decorrelation by multiplying the signal in the frequency domain by the reference signal; a phase rotation estimation unit estimating a phase rotation value through inverse discrete Fourier transform of the decorrelated signal; a channel transformation matrix processing unit that checks a channel transformation matrix using the phase rotation value and outputs a value obtained by multiplying the decorrelated signal by the channel transformation matrix; A phase shifter unit that identifies a phase shift matrix using the phase rotation value, and estimates a channel from a subcarrier of an order determined through the phase shift matrix by multiplying a value obtained by multiplying the decorrelated signal output from the channel transformation matrix processing unit by the channel estimation transformation matrix by the phase shift matrix; and an edge subcarrier processing unit copying a channel estimation value of a subcarrier adjacent to a subcarrier whose channel cannot be estimated.

A channel estimation method according to an embodiment includes converting a received pilot signal into a signal in a frequency domain through fast Fourier transform; generating a reference signal; obtaining a decorrelation signal by performing decorrelation of multiplying the signal in the frequency domain by the reference signal; obtaining a phase rotation value through inverse discrete Fourier transform of the decorrelated signal; and determining a channel transformation matrix using the phase rotation value, and estimating a channel from a first subcarrier by multiplying the decorrelated signal by the channel transformation matrix.

This document can effectively remove interference between cyclic shifts in a multi-cyclic shift interference environment where time offsets exist, and easily obtain a channel estimation value of a subcarrier while distributing an edge area, which is an area in which a channel estimation value of a subcarrier cannot be calculated. A technique is proposed.

1 is a diagram showing the configuration of a channel estimation apparatus according to an embodiment.
2 is a diagram showing the configuration of a channel estimation apparatus according to another embodiment.
3 is a flowchart illustrating a process of estimating a channel in a channel estimation apparatus according to an embodiment.
4 is a flowchart illustrating a process of estimating a channel in a channel estimation apparatus according to another embodiment.
5 is a diagram illustrating an example of estimating a channel by multiplying 24 subcarriers by a channel transformation matrix in a channel estimation apparatus according to an embodiment.
6 is a diagram illustrating an example of estimating a channel by multiplying 24 subcarriers by a channel transformation matrix and a phase shift matrix in a channel estimation apparatus according to another embodiment.
7 is a diagram illustrating another example of estimating a channel by multiplying 24 subcarriers by a channel transformation matrix and a phase shift matrix in a channel estimation apparatus according to another embodiment.

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. However, since various changes can be made to the embodiments, the scope of the patent application is not limited or limited by these embodiments. It should be understood that all changes, equivalents or substitutes to the embodiments are included within the scope of rights.

Terms used in the examples are used only for descriptive purposes 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 "having" are intended to specify that a feature, number, step, operation, component, part, or combination thereof described in the specification exists, but it should be understood that the presence or addition of one or more other features or numbers, steps, operations, components, parts, or combinations thereof is not excluded in advance.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by a person of ordinary skill in the art to which the embodiment belongs. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the related art, and are not interpreted in an ideal or excessively formal meaning unless explicitly defined in the present application.

In addition, in the description with reference to the accompanying drawings, the same reference numerals are given to the same components regardless of reference numerals, and overlapping descriptions thereof will be omitted. In describing the embodiment, if it is determined that a detailed description of a related known technology may unnecessarily obscure the gist of the embodiment, the detailed description will be omitted.

Also, terms such as first, second, A, B, (a), and (b) may be used in describing the components of the embodiment. These terms are only used to distinguish the component from other components, and the nature, order, or order of the corresponding component is not limited by the term. When an element is described as being “connected”, “coupled” or “connected” to another element, it will be understood that the element may be directly connected or connected to the other element, but that another element may be “connected”, “coupled” or “connected” between each element.

Components included in one embodiment and components having common functions will be described using the same names in other embodiments. Unless stated to the contrary, descriptions described in one embodiment may be applied to other embodiments, and detailed descriptions will be omitted to the extent of overlap.

In the following, according to an embodiment of the present invention An apparatus and method for estimating a channel using a multi-cyclic shift separation technique will be described in detail with reference to FIGS. 1 to 7 attached.

1 is a diagram showing the configuration of a channel estimation apparatus according to an embodiment.

Referring to FIG. 1 , the channel estimation apparatus 100 may include a fast Fourier transform unit 110, a signal extraction unit 120, a reference signal generator 130, a decorrelation unit 140, a phase rotation estimation unit 150, a channel transformation matrix processing unit 160, and an edge subcarrier processing unit 180.

The fast Fourier transform unit 110 may transform the received pilot signal into a signal in the frequency domain through Fast Fourier Transform (FFT).

The signal extractor 120 may extract only the frequency domain of the receiving device from the signal in the frequency domain transformed by the fast Fourier transform unit 110 and provide the extracted signal to the decorrelator 140 . At this time, the signal extractor 120 may be omitted in some cases.

The reference signal generating unit 130 may generate a reference signal corresponding to the receiving device and transmit it to the decorrelation unit 140 .

The decorrelator 140 performs decorrelation by multiplying the frequency domain signal received from the signal extractor 120 by a reference signal to obtain a decorrelated signal, and the decorrelator 150 and the channel transformation matrix processor 160 may transmit the decorrelated signal.

The phase rotation estimator 150 estimates a phase rotation value of the decorrelated signal received from the decorrelation unit 140 through an Inverse Discrete Fourier Transform (IDFT), and transmits the phase rotation value to the channel transformation matrix processing unit 160.

The phase rotation estimator 150 converts the decorrelated signal into a time domain signal by inverse discrete Fourier transform, obtains a time offset corresponding to a position having a peak power in the time domain signal, and converts the time offset into a frequency domain to obtain a phase rotation value (Phase Rotation).

The channel transformation matrix processing unit 160 may determine the channel transformation matrix using the phase rotation value and estimate the channel from the first subcarrier by multiplying the decorrelated signal by the channel transformation matrix.

In this case, the channel transformation matrix is an inverse matrix of the frequency transformation matrix.

The frequency transformation matrix is a Vandermonde matrix formed by sampling subcarriers of a decorrelated signal, which is a polynomial represented by a channel and a time offset, and can be expressed as in Equation 1 below.

[Equation 1]

y = Ah

Here, y is a vector representing the decorrelated signal, A is a frequency transformation matrix, and h is a vector having a channel estimation value.

The edge subcarrier processing unit 180 may copy a channel estimation value of a subcarrier adjacent to a subcarrier for which the channel transformation matrix processing unit 160 cannot calculate a channel estimation value, that is, for which a channel cannot be estimated.

2 is a diagram showing the configuration of a channel estimation apparatus according to another embodiment.

Referring to FIG. 2 , the channel estimation apparatus 200 may include a fast Fourier transform unit 210, a signal extraction unit 220, a reference signal generator 230, a decorrelation unit 240, a phase rotation estimation unit 250, a channel transformation matrix processing unit 260, a phase shifter unit 270, and an edge subcarrier processing unit 280.

The fast Fourier transform unit 210 may transform the received pilot signal into a signal in the frequency domain through Fast Fourier Transform (FFT).

The signal extractor 220 may extract only the frequency domain of the receiving device from the signal in the frequency domain transformed by the fast Fourier transform unit 210 and provide the extracted signal to the decorrelator 240 . At this time, the signal extractor 220 may be omitted in some cases.

The reference signal generating unit 230 may generate a reference signal corresponding to the receiving device and transmit it to the decorrelation unit 240 .

The decorrelator 240 performs decorrelation by multiplying the reference signal by the signal in the frequency domain received from the signal extractor 220 to obtain a decorrelated signal, and the decorrelator 250. The phase rotation estimator 250 and the channel transformation matrix processor 260.

The phase rotation estimator 250 estimates a phase rotation value of the decorrelated signal received from the decorrelation unit 240 through an inverse discrete Fourier transform (IDFT), and transmits the phase rotation value to the channel transformation matrix processing unit 260 and the phase shifter unit 270.

The phase rotation estimator 250 converts the decorrelated signal into a time domain signal by inverse discrete Fourier transform, obtains a time offset corresponding to a position having a peak power in the time domain signal, and converts the time offset into a frequency domain to obtain a phase rotation value (Phase Rotation).

The channel transformation matrix processing unit 260 may check the channel transformation matrix using the phase rotation value and transmit a value obtained by multiplying the decorrelated signal by the channel transformation matrix to the phase shifter 270 .

In this case, the channel transformation matrix is an inverse matrix of the frequency transformation matrix. And, the frequency transformation matrix may be a Vandermonde matrix formed by sampling subcarriers of a decorrelation signal, which is a polynomial expressed by a channel and a time offset.

The phase shifter 270 checks the phase shift matrix using the phase rotation value, and multiplies the value obtained by multiplying the decorrelated signal output from the channel transformation matrix processing unit 260 by the channel estimation transformation matrix by the phase shift matrix to estimate the channel from the subcarrier in the order determined through the phase shift matrix. In this case, the phase shift matrix may be a diagonal matrix.

The edge subcarrier processing unit 280 may copy a channel estimation value of a subcarrier adjacent to a subcarrier for which the phase shifter unit 270 cannot calculate a channel estimation value, that is, for which a channel cannot be estimated.

An example of a process of deriving a frequency transformation matrix and a phase shift matrix for channel estimation described with reference to FIGS. 1 and 2 and estimating a channel using the frequency transformation matrix and the phase shift matrix will be described with reference to FIGS. 5 to 7 below.

In this document, a channel estimation apparatus decorrelates a received signal with a reference signal of a specific cyclic shift to generate a decorrelated signal. And, it is assumed that the channel estimation device can obtain a time offset for each cyclic shift by performing an inverse discrete Fourier transform (IDFT) on the decorrelated signal in the frequency domain.

At this time, due to the special properties between the inverse discrete Fourier transform and the cyclic shift, the position with the peak power at the output of the inverse discrete Fourier transform rotates cyclically according to the cyclic shift. This is also the reason for using the term cyclic shift. The time offset corresponding to the peak power is found in the output of the inverse discrete Fourier transform, and how much phase rotation of this time offset occurs for each subcarrier in the frequency domain is the basic property of the Fourier Transform. is available. where the phase rotation value is can be expressed as

channel with time offset When one user terminal (UE) transmits using a different cyclic shift (CS), the signal after decorrelation with the reference signal of a specific user terminal can be expressed as in Equation 2 below.

[Equation 2]

here, Is A signal received on a th subcarrier, Represents the amount of phase (Phase) that rotates for each subcarrier in frequency by a time offset, may represent a relative cyclic shift value assigned to each user terminal.

According to LTE (long term evolution) and NR (New Radio) standards, or can have the form of

In order to more easily explain the operation of the invention, an example will be described. In case of corresponds to, In case of 4 user terminals corresponding to , that is, a case in which four cyclic shifts are transmitted will be described as an example.

The signal received on the th subcarrier ( ) is the user terminal according to the cyclic shift ( ) of the channel ( ) and the time offset ( ), it can be expressed as in <Equation 3> below.

[Equation 3]

If the above <Equation 3> is expressed in the form of a matrix-vector, as shown in <Equation 4> below. can be expressed as Here, y is the decorrelated signal, A is the frequency transformation matrix, and h is the channel estimation value.

[Equation 4]

here, The subscript of means a subcarrier and and The subscript of means the index of the user terminal.

Assuming that is the same in adjacent subcarriers, the channel estimation device is solved to obtain the channel of the first subcarrier of the 0th user terminal. Calculate the channel estimation value for , and the channel value for the second subcarrier can be obtained as shown in Equation 5 below by applying a sliding window.

[Equation 5]

When applied as in Equation 5, channel estimation values of each subcarrier can be obtained as shown in FIG. 5 below.

5 is a diagram illustrating an example of estimating a channel by multiplying 24 subcarriers by a channel transformation matrix in a channel estimation apparatus according to an embodiment.

Referring to FIG. 5 , since channel estimation values cannot be obtained for the last three subcarriers, the channel estimation unit 100 has no choice but to copy and use the channel estimation values of the fourth subcarrier from the last.

This is because signals received on three adjacent subcarriers including the subcarrier are used to estimate the channel of a specific subcarrier. In the example of FIG. 5, the channel of subcarrier 0, which is the first subcarrier Signals received on subcarriers 0, 1, 2, and 3 in order to estimate ( ) is used.

As a result, in FIG. 5, the signal received on the 20th subcarrier ( ), the channel estimation value can be calculated, but the signals received on subcarriers 21, 22, and 23 ( ) cannot calculate the channel estimation value, so the channel estimation value of the 20th subcarrier can be copied and applied as the channel estimation value of the 21st, 22nd, and 23rd subcarriers.

However, for channel estimation of a specific subcarrier, it is more preferable to use signals received on subcarriers in front and behind of the corresponding subcarrier rather than using only subcarriers in the backward direction as shown in the example of FIG. The edge area of a subcarrier is an area in which a channel estimation value cannot be calculated at the beginning or end of a received signal, and in the case of FIG. 5, subcarriers 21, 22, and 23 can be referred to as edge areas.

In addition, in the case of a reference signal using frequency resources separated by a comb-type, it is advantageous to equally distribute the edge area used by copying to the beginning and end of the received signal as much as possible. To do so, <Equation 3> in the example of the above four cyclic shifts can be changed as shown in <Equation 6> below based on the third subcarrier.

[Equation 6]

of <Equation 6> is solved to obtain the channel of the third subcarrier of the 0th user terminal Obtain an estimated value for , and the channel value for the fourth subcarrier can be obtained as shown in Equation 7 below by applying a sliding window similarly to the prior art.

[Equation 7]

In the case of <Equation 6>, the two subcarriers of the first subcarrier and the second subcarrier may copy the channel of the third subcarrier, and the last subcarrier may copy the channel of the second to last subcarrier.

of <Equation 4> has the advantage that the inverse matrix can be easily obtained because the A matrix is in the form of a Vandermonde matrix, but subcarriers for which the estimated channel value cannot be obtained tend to be concentrated at the last edge.

of <Equation 6> Although there is no general formula for the inverse matrix of the B matrix, it is characterized in that subcarriers for which an estimated channel value cannot be obtained can be distributed to both edges.

At this time, the relationship between the matrix B of <Equation 6> and the matrix A of <Equation 4> and the special shape of the matrix A can be derived from the following <Equation 8>.

[Equation 8]

here, is the phase shift matrix.

When <Equation 8> is applied to <Equation 6>, it can be expressed as <Equation 9> below.

[Equation 9]

That is, according to Equation 9 Is in the first term of It can be confirmed that it can be obtained by multiplying by .

When applied as in Equation 6, channel estimation values of each subcarrier can be obtained as shown in FIG. 6 below.

6 is a diagram illustrating an example of estimating a channel by multiplying 24 subcarriers by a channel transformation matrix and a phase shift matrix in a channel estimation apparatus according to another embodiment.

Referring to FIG. 6 , since the channel estimation unit 200 cannot obtain channel estimation values for the first two subcarriers and the last one subcarrier, the channel estimation value of the third subcarrier is copied and used for the first two subcarriers, and the channel estimation value of the second to last subcarrier is copied and used for the last one subcarrier.

In the example of FIG. 6, the channel of the second subcarrier, which is the third subcarrier. Signals received on subcarriers 0, 1, 2, and 3 in order to estimate ( ) can be used.

As a result, the example of FIG. 6 shows the signal received on the second subcarrier ( ), the signal received on the 22nd subcarrier ( ), the channel estimation value can be calculated, but the signals received on subcarriers 0, 1, and 23 ( ) cannot calculate the channel estimation value, so the channel estimation value of subcarrier 2 is copied and applied as the channel estimation value of subcarriers 0 and 1, and the channel estimation value of subcarrier 22 is copied and applied as the channel estimation value of subcarrier 23.

<Equation 3> in the example of the above four cyclic shifts can be changed as shown in <Equation 10> below based on the second subcarrier.

[Equation 10]

At this time, the relationship between the matrix C of <Equation 10> and the matrix A of <Equation 4> and the special shape of the matrix A can be derived from the following <Equation 11>.

[Equation 11]

When <Equation 11> is applied to <Equation 10>, it can be expressed as <Equation 12> below.

[Equation 12]

When applied as in Equation 10, channel estimation values of each subcarrier can be obtained as shown in FIG. 7 below.

7 is a diagram illustrating another example of estimating a channel by multiplying 24 subcarriers by a channel transformation matrix and a phase shift matrix in a channel estimation apparatus according to another embodiment.

Referring to FIG. 7 , since the channel estimation unit 200 cannot obtain channel estimation values for the first subcarrier and the last two subcarriers, the channel estimation value of the second subcarrier is copied and used for the first one subcarrier, and the channel estimation value of the third subcarrier before the last two subcarriers is copied and used.

In the example of FIG. 6, the channel of subcarrier No. 1, which is the second subcarrier Signals received on subcarriers 0, 1, 2, and 3 in order to estimate ( ) can be used.

As a result, the example of FIG. 7 shows a signal received on subcarrier No. 1 ( ), the signal received on the 21st subcarrier ( ), the channel estimation value can be calculated, but the signals received on subcarriers 0, 22, and 23 ( ) cannot calculate the channel estimation value, so the channel estimation value of subcarrier #1 can be copied and applied as the channel estimation value of subcarrier #0, and the channel estimation value of subcarrier #21 can be copied and applied as the channel estimation value of subcarriers #22 and #23.

Hereinafter, the method according to the present invention configured as described above will be described with reference to the drawings below.

3 is a flowchart illustrating a process of estimating a channel in a channel estimation apparatus according to an embodiment.

Referring to FIG. 3, the channel estimation apparatus 100 transforms the received pilot signal into a signal in the frequency domain through fast Fourier transform (310).

Then, the channel estimating apparatus 100 extracts only the frequency domain of the receiving device from the signal in the frequency domain (320).

Then, the channel estimating device 100 generates a reference signal corresponding to the receiving device (330). In this case, the reference signal may be a preset signal corresponding to the corresponding receiving field.

Then, the channel estimating apparatus 100 obtains a decorrelation signal by performing decorrelation by multiplying a reference signal by a signal in the frequency domain from which only the frequency domain of the corresponding receiving device is extracted (340).

Then, the channel estimation apparatus 100 obtains a phase rotation value through inverse discrete Fourier transform of the decorrelated signal (350).

In this case, the phase rotation value may be obtained by converting the decorrelated signal into a time domain signal by inverse discrete Fourier transform, obtaining a time offset corresponding to a position having a peak power in the time domain signal, and converting the time offset into a frequency domain.

Then, the channel estimating apparatus 100 may check the channel transformation matrix using the phase rotation value and estimate the channel from the first subcarrier by multiplying the decorrelated signal by the channel transformation matrix (360).

In this case, the channel transformation matrix is an inverse matrix of the frequency transformation matrix, and the frequency transformation matrix may be a Vandermonde matrix constructed by sampling subcarriers of a decorrelated signal that is a polynomial expressed by a channel and a time offset.

Then, the channel estimating apparatus 100 copies a channel estimation value of a subcarrier adjacent to a subcarrier for which a channel cannot be estimated (380).

4 is a flowchart illustrating a process of estimating a channel in a channel estimation apparatus according to another embodiment.

Referring to FIG. 4, the channel estimation apparatus 100 transforms the received pilot signal into a signal in the frequency domain through fast Fourier transform (410).

Then, the channel estimating apparatus 100 extracts only the frequency domain of the receiving device from the signal in the frequency domain (420).

Then, the channel estimating device 100 generates a reference signal corresponding to the receiving device (430). In this case, the reference signal may be a preset signal corresponding to the corresponding receiving field.

Then, the channel estimating apparatus 100 obtains a decorrelated signal by performing decorrelation by multiplying a signal in the frequency domain from which only the frequency domain of the corresponding receiving device is extracted by a reference signal (440).

Then, the channel estimation apparatus 100 obtains a phase rotation value through inverse discrete Fourier transform of the decorrelated signal (450).

In this case, the phase rotation value may be obtained by converting the decorrelated signal into a time domain signal by inverse discrete Fourier transform, obtaining a time offset corresponding to a position having a peak power in the time domain signal, and converting the time offset into a frequency domain.

Then, the channel estimation apparatus 100 checks the channel transformation matrix using the phase rotation value, and multiplies the decorrelated signal by the channel transformation matrix (460).

In this case, the channel transformation matrix is an inverse matrix of the frequency transformation matrix, and the frequency transformation matrix may be a Vandermonde matrix constructed by sampling subcarriers of a decorrelated signal that is a polynomial expressed by a channel and a time offset.

Then, the channel estimating apparatus 100 checks the phase shift matrix using the phase rotation value, and in operation 460, multiplies the value obtained by multiplying the decorrelated signal by the channel transformation matrix by the phase shift matrix to estimate the channel from the subcarrier in the order determined through the phase shift matrix (470). In this case, the phase shift matrix may be a diagonal matrix.

Then, the channel estimating apparatus 100 copies a channel estimation value of a subcarrier adjacent to a subcarrier for which a channel cannot be estimated (480).

The method according to the embodiment may be implemented in the form of program instructions that can be executed through various computer means and recorded on a computer readable medium. The computer readable medium may store program instructions, data files, data structures, etc. alone or in combination. Program commands recorded on the medium may be specially designed and configured for the embodiment or may be known and usable to those skilled in computer software. Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks and magnetic tapes, optical media such as CD-ROMs and DVDs, magneto-optical media such as floptical disks, and hardware devices specially configured to store and execute program instructions such as ROM, RAM, and flash memory. Examples of program instructions include high-level language codes that can be executed by a computer using an interpreter or the like as well as machine language codes such as those produced by a compiler. The hardware devices described above may be configured to operate as one or more software modules to perform the operations of the embodiments, and vice versa.

Software may include a computer program, code, instructions, or a combination of one or more of these, and may configure a processing device to operate as desired, or may independently or collectively direct a processing device. Software and/or data may be permanently or temporarily embodied in any tangible machine, component, physical device, virtual equipment, computer storage medium or device, or transmitted signal wave, to be interpreted by, or to provide instructions or data to, a processing device. Software may be distributed on networked computer systems and stored or executed in a distributed manner. Software and data may be stored on one or more computer readable media.

As described above, although the embodiments have been described with limited drawings, those skilled in the art can apply various technical modifications and variations based on the above. For example, even if the described techniques are performed in an order different from the described method, and/or components of the described system, structure, device, circuit, etc. are combined or combined in a different form from the described method, or replaced or substituted by other components or equivalents, appropriate results can be achieved.

Therefore, other implementations, other embodiments, and equivalents of the claims are within the scope of the following claims.

200: channel estimation device
210: fast Fourier transform unit
220: signal extraction unit
230: reference signal generator
240: reverse correlation
250: phase rotation estimation unit
260: channel transformation matrix processing unit
270: phase shifter unit
280: edge subcarrier processing unit

Claims (20)

a fast Fourier transform unit for transforming the received pilot signal into a signal in a frequency domain through fast Fourier transform;
a reference signal generator for generating a reference signal;
a decorrelation unit that obtains a decorrelated signal by performing decorrelation by multiplying the signal in the frequency domain by the reference signal;
a phase rotation estimation unit estimating a phase rotation value through inverse discrete Fourier transform of the decorrelated signal; and
A channel transformation matrix processor for determining a channel transformation matrix using the phase rotation value and estimating a channel from a first subcarrier by multiplying the decorrelated signal by the channel transformation matrix
A channel estimation device comprising a.
According to claim 1,
Edge subcarrier processor for copying channel estimation values of subcarriers adjacent to subcarriers whose channels cannot be estimated
Channel estimation device further comprising a.
According to claim 1,
A phase shifter unit that identifies a phase shift matrix using the phase rotation value, and estimates a channel from a subcarrier in the order determined through the phase shift matrix by multiplying a value obtained by multiplying the decorrelated signal output from the channel transformation matrix processing unit by the channel estimation transformation matrix by the phase shift matrix.
Channel estimation device further comprising a.
According to claim 1,
The phase rotation estimation unit,
converting the decorrelated signal into a time domain signal by inverse discrete Fourier transform;
Obtaining a time offset corresponding to a position having a peak power in the time domain signal;
Converting the time offset to a frequency domain to obtain the phase rotation value
channel estimation device.
According to claim 1,
A signal extraction unit for extracting only the frequency domain of the receiving device from the signal in the frequency domain transformed by the fast Fourier transform unit and providing the extracted signal to the decorrelation unit.
Channel estimation device further comprising a.
According to claim 1,
The channel transformation matrix,
is the inverse matrix of the frequency transform matrix,
The frequency transformation matrix,
A Vandermonde matrix constructed by sampling the subcarriers of the decorrelated signal, which is a polynomial represented by channels and time offsets, is expressed as in Equation 1 below
channel estimation device.
[Equation 1]
y = Ah
Here, y is a vector representing the decorrelated signal, A is the frequency transformation matrix, and h is a vector having a channel estimation value.
According to claim 1,
The phase shift matrix,
a diagonal matrix
channel estimation device.
a fast Fourier transform unit for transforming the received pilot signal into a signal in a frequency domain through fast Fourier transform;
a reference signal generator for generating a reference signal;
a decorrelation unit that obtains a decorrelated signal by performing decorrelation by multiplying the signal in the frequency domain by the reference signal;
a phase rotation estimation unit estimating a phase rotation value through inverse discrete Fourier transform of the decorrelated signal;
a channel transformation matrix processing unit that checks a channel transformation matrix using the phase rotation value and outputs a value obtained by multiplying the decorrelated signal by the channel transformation matrix;
A phase shifter unit that identifies a phase shift matrix using the phase rotation value, and estimates a channel from a subcarrier of an order determined through the phase shift matrix by multiplying a value obtained by multiplying the decorrelated signal output from the channel transformation matrix processing unit by the channel estimation transformation matrix by the phase shift matrix; and
Edge subcarrier processor for copying channel estimation values of subcarriers adjacent to subcarriers whose channels cannot be estimated
A channel estimation device comprising a.
According to claim 8,
The phase rotation estimation unit,
converting the decorrelated signal into a time domain signal by inverse discrete Fourier transform;
Obtaining a time offset corresponding to a position having a peak power in the time domain signal;
Converting the time offset to a frequency domain to obtain the phase rotation value
channel estimation device.
According to claim 8,
A signal extraction unit for extracting only the frequency domain of the receiving device from the signal in the frequency domain transformed by the fast Fourier transform unit and providing the extracted signal to the decorrelation unit.
Channel estimation device further comprising a.
According to claim 8,
The channel transformation matrix,
is the inverse matrix of the frequency transform matrix,
The frequency transformation matrix,
A Vandermonde matrix constructed by sampling the subcarriers of the decorrelated signal, which is a polynomial represented by channels and time offsets, is expressed as in Equation 1 below
channel estimation device.
[Equation 1]
y = Ah
Here, y is a vector representing the decorrelated signal, A is the frequency transformation matrix, and h is a vector having a channel estimation value.
According to claim 8,
The phase shift matrix,
a diagonal matrix
channel estimation device.
converting the received pilot signal into a signal in the frequency domain through fast Fourier transform;
generating a reference signal;
obtaining a decorrelation signal by performing decorrelation of multiplying the signal in the frequency domain by the reference signal;
obtaining a phase rotation value through inverse discrete Fourier transform of the decorrelated signal; and
Checking a channel transformation matrix using the phase rotation value, and estimating a channel from a first subcarrier by multiplying the decorrelated signal by the channel transformation matrix.
Channel estimation method comprising a.
According to claim 13,
An operation of copying a channel estimation value of a subcarrier adjacent to a subcarrier for which a channel cannot be estimated
Channel estimation method further comprising.
According to claim 13,
The operation of estimating the channel,
Checking a channel estimation transformation matrix using the phase rotation value;
Checking the phase shift matrix using the phase rotation value,
Estimating a channel from a subcarrier of an order determined through the phase shift matrix by multiplying the decorrelated signal by the channel estimation transformation matrix and the phase shift matrix
Channel estimation method.
According to claim 13,
The operation of obtaining the phase rotation value,
converting the decorrelated signal into a time domain signal by inverse discrete Fourier transform;
Obtaining a time offset corresponding to a position having a peak power in the time domain signal;
Converting the time offset to a frequency domain to obtain the phase rotation value
Channel estimation method.
According to claim 13,
Prior to an operation of obtaining a decorrelated signal by performing decorrelation of multiplying the signal in the frequency domain by the reference signal,
Extracting only the frequency domain of the corresponding receiving device from the signal in the frequency domain
Including more,
The signal in the frequency domain for which decorrelation is performed in the operation of obtaining the decorrelated signal,
The signal in the frequency domain from which only the frequency domain of the corresponding receiving device is extracted.
Channel estimation method.
According to claim 13,
The channel transformation matrix,
is the inverse matrix of the frequency transform matrix,
The frequency transformation matrix,
A Vandermonde matrix constructed by sampling the subcarriers of the decorrelated signal, which is a polynomial represented by channels and time offsets, is expressed as in Equation 1 below
Channel estimation method.
[Equation 1]
y = Ah
Here, y is a vector representing the decorrelated signal, A is the frequency transformation matrix, and h is a vector having a channel estimation value.
According to claim 13,
The phase shift matrix,
a diagonal matrix
Channel estimation method.
A computer-readable recording medium in which a program for executing the method of any one of claims 13 to 19 is recorded.

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