WO2013178090A1

WO2013178090A1 - Channel estimation method, channel estimation device and receiver

Info

Publication number: WO2013178090A1
Application number: PCT/CN2013/076569
Authority: WO
Inventors: 李琦
Original assignee: 华为技术有限公司
Priority date: 2012-05-31
Filing date: 2013-05-31
Publication date: 2013-12-05
Also published as: CN103457885A; CN103457885B

Abstract

Provided are a channel estimation method, a channel estimation device and a receiver. The method includes: performing channel estimation on a received reference signal to acquire a first channel response of the reference signal in a frequency domain; transforming the first channel response into a time domain to acquire a second channel response of the reference signal in the time domain; filtering the power delay spectrum of each path in the time domain to acquire the average power of each path in the time domain; determining a path with an average power lower than a set threshold to be a virtual path; removing the channel response of the virtual path from the second channel response to acquire a third channel response; and transforming the third channel response into the frequency domain to acquire a fourth channel response of the reference signal. The embodiments of the present invention realize an increase of the accuracy of channel estimation.

Description

Channel estimation method, channel estimation apparatus and receiver The present application claims to Chinese Patent Application No. 201210175481.0, entitled "Channel Estimation Method, Channel Estimation Apparatus and Receiver", filed on May 31, 2012 Priority is hereby incorporated by reference in its entirety. Technical field

The present invention relates to communication technologies, and in particular, to a channel estimation method, a channel estimation apparatus, and a receiver. Background technique

After being transmitted through the transmitting end, the data is transmitted to the receiving end through the propagation of the wireless channel. Various interference factors in the wireless channel may affect the transmitted data. Therefore, the data received by the receiving end may be larger than the data transmitted by the transmitting end. Not the same. Channel estimation is usually required to equalize the received data and recover the data against the effects of the channel. At present, the reference signal known by the receiving end is usually transmitted while transmitting the data signal, and the receiving end estimates the channel response experienced by the reference signal according to the received reference signal and the known reference signal, thereby obtaining the channel response of the data signal.

In the prior art, the receiving end first obtains the channel response of the reference signal in the frequency domain resource location according to the received reference signal, and then transforms the channel response of the reference signal into the time domain, and the time domain channel has a maximum time delay path. The channel response is set to 0 to perform noise reduction processing on the channel response of the reference signal, and then transform the noise-reduced time domain channel response into the frequency domain. However, channel estimation is inaccurate due to noise and interference in the real channel environment. Summary of the invention

Embodiments of the present invention provide a channel estimation method, a channel estimation apparatus, and a receiver to improve channel estimation accuracy. In one aspect, an embodiment of the present invention provides a channel estimation method, including: performing channel estimation on a received reference signal, and acquiring a first channel response of the reference signal in a frequency domain;

Transforming the first channel response into a time domain to obtain a second channel response of the reference signal in a time domain;

Filtering the power delay spectrum of each path in the time domain to obtain the average power of each path in the time domain;

Determining a path whose average power is lower than a set threshold as an virtual path;

Removing a channel response of the virtual path in the second channel response to obtain a third channel response; and transforming the third channel response into a frequency domain to obtain a fourth channel response of the reference signal. In another aspect, an embodiment of the present invention provides a channel estimation apparatus, including:

a first processor, configured to perform channel estimation on the received reference signal, and obtain a first channel response of the reference signal in a frequency domain;

a converter, configured to transform the first channel response into a time domain, to obtain a second channel response of the reference signal in a time domain;

a filter, configured to filter a power delay spectrum of each path in the time domain to obtain an average power of each path in the time domain;

The first processor is further configured to: determine a path whose average power is lower than a set threshold as a virtual path; remove a channel response of the virtual path in the second channel response, to obtain a third channel response; The converter is further configured to transform the third channel response into a frequency domain to obtain a fourth channel response of the reference signal.

In another aspect, an embodiment of the present invention provides a receiver, including:

a receiver, configured to receive a reference signal and a data signal;

Channel estimation means, configured to perform channel estimation on the received reference signal, acquire a first channel response of the reference signal in a frequency domain; transform the first channel response into a time domain, to obtain the reference signal in a time domain Second channel response; performing power delay spectrum for each path in the time domain Filtering, obtaining an average power of each path in the time domain; determining a path whose average power is lower than a set threshold as a virtual path; removing a channel response of the virtual path in the second channel response to obtain a third channel response; Converting the third channel response to the frequency domain to obtain a fourth channel response of the reference signal;

The second processor is configured to perform interpolation on a fourth channel response obtained by the channel estimation device to obtain a channel response of the data signal;

The demodulator is configured to demodulate the data signal received by the receiver according to a channel response of the data signal.

The channel estimation method, the channel estimation apparatus, and the receiver provided by the embodiment of the present invention, after acquiring the channel response of the reference signal in the time domain, filtering the power delay spectrum of each path in the time domain to obtain the average power of each path, and then averaging The path whose power is lower than the set threshold is determined as the virtual path, and the channel response of the virtual path is removed in the channel response in the time domain, thereby improving the accuracy of the channel estimation. DRAWINGS

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings to be used in the embodiments or the description of the prior art will be briefly described below. Obviously, the drawings in the following description are Some embodiments of the present invention may also be used to obtain other drawings based on these drawings without departing from the skilled artisan.

1 is a flowchart of an embodiment of a channel estimation method provided by the present invention;

2 is a flowchart of still another embodiment of a channel estimation method provided by the present invention;

FIG. 3 is a schematic diagram showing the relationship between time delay and power of each path in the time domain in the channel estimation method provided by the present invention; FIG.

4 is a schematic structural diagram of an embodiment of a channel estimation apparatus according to the present invention; FIG. 5 is a schematic structural diagram of an embodiment of a receiver provided by the present invention. detailed description The technical solutions in the embodiments of the present invention are clearly and completely described in the following with reference to the accompanying drawings in the embodiments of the present invention. It is a partial embodiment of the invention, and not all of the embodiments. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present invention without departing from the inventive scope are the scope of the present invention.

The channel estimation method provided by the embodiment of the present invention may be used to estimate an uplink channel or a downlink channel. Specifically, it can be performed by the receiving end of the reference signal. For example, in the uplink channel, the receiving end can receive the reference signal transmitted in the uplink channel. If the transmitting end of the reference signal is a user terminal in the uplink channel, the receiving end may be a base station or a relay station; if the transmitting end of the reference signal is a relay station, the receiving end may be a base station or a previous hop relay station. In the downlink channel, the receiving end can receive the reference signal sent in the downlink channel. If the transmitting end of the reference signal is the base station, the receiving end can be the terminal or the relay station; if the transmitting end of the reference signal is the relay station, the receiving end can be Terminal or next hop relay station.

The reference signal involved in the embodiment of the present invention may also be referred to as a pilot signal.

FIG. 1 is a flowchart of an embodiment of a channel estimation method according to the present invention. As shown in FIG. 1, an execution body of the following steps is a receiving end. As described above, the receiving end may be a terminal, a base station, or a relay station. The method includes:

S101. Perform channel estimation on the received reference signal, and obtain a first channel response of the reference signal in the frequency domain.

It is assumed that the reference signal sequence of one transmit antenna of the transmitting end on the Orthogonal Frequency Division Multiplexing (OFDM) symbol is:

P = [ (0) (l) ··· P(M - l)} where M is the number of reference signals on the OFDM symbol, that is, M represents the sequence length of the reference signal, and M is an integer greater than 0; M - ¹ ) indicates the value of the Mth reference signal, the channel response from the transmitting antenna of the transmitting end to the receiving antenna of the receiving end is ^, the noise is, r is the serial number of the receiving antenna, = 0,1,·· · · ^ _ 1 , R is the total number of receiving antennas. Then, the reference signal received by the receiving antenna at the receiving end is:

Y ^r = H ^r P + N ^r

The receiving end can perform channel estimation on the reference signal by using various existing methods to obtain a channel response of the reference signal.

For example, the receiving end may perform least square (LS) channel estimation on the received reference signal to obtain a channel response ^A of the reference signal of the receiving antenna: i _LS = Y ^r IP = HW IP . In the embodiment of the present invention, a method for performing channel estimation on the received reference signal is not limited.

It should be noted that the first channel response obtained by performing channel estimation on the received reference signal in S101 is the channel response of the reference signal in the frequency domain.

S102. Transform a first channel response into a time domain to obtain a second channel response of the reference signal in a time domain.

After the channel response of the reference signal in the frequency domain is obtained in S101, the channel response in the frequency domain of the reference signal obtained in S101 needs to be transformed into the time domain to obtain a second channel response.

For example, the channel response of the reference signal in the frequency domain, that is, the inverse of the Fourier transform of the first channel response, may be performed to obtain a channel response of the reference channel in the time domain, that is, the second channel response.

/ ^ ( "), Η = 0Λ, · · ·, Ν! Which, Inverse Fast Fourier Transform _(Inverse Fast Fourier

Transform, IFFT) is the number of points of the inverse Fourier transform, and ceil means up to the whole.

It should be noted that since the number of IFFTs of the inverse Fourier transform is 2 nth power (n is an integer greater than or equal to 0), if the data length of the first channel response cannot satisfy the number of points of the inverse Fourier transform IFFT The demand may be complemented by _ zeros after the first channel response, and the first channel response after complementing 0 is recorded, and the inverse Fourier transform of the channel response is performed according to the following formula:

= IFFT(H[ _S ) 5103. Filter the power delay spectrum of each path in the time domain to obtain an average power of each path in the time domain.

Transforming the first channel response of the reference signal into the time domain to obtain a second channel response _n = 0, l, '" , N _IFFT - l , each "corresponding to a path in the time domain, the path in the time domain means, reference The signal is reflected and/or refracted from the transmitting end to the path traveled by the receiving end, and different paths in the time domain are distinguished by the delay of the path.

Due to the interference and noise in the real channel environment, the virtual path will appear in the middle. These virtual paths appear only in an instant, disappear in the next moment, and cannot transmit an effective reference signal, thus affecting the accuracy of the channel response estimation of the reference signal. At the moment of the disturbance, the power of the virtual path may be relatively large. However, since the virtual path only appears instantaneously, the next moment disappears. Therefore, the average power on the virtual path is lower than other paths in the time domain.

Accordingly, the power delay spectrum of each path in the time domain can be filtered to obtain the average power of each path in the time domain, thereby eliminating the influence of interference on the instantaneous power of the virtual path, and obtaining an average power that can reflect the power situation of each path. Then, the path with the power lower than the set threshold is judged by S104, and the virtual path in the time domain is determined.

Optionally, the power of each path may be the average power of the reference signals received by each receiving antenna in the current subframe. For example, the alpha delay filter can be used to filter the power delay of each path in the time domain to obtain the average power of each path in the time domain.

5104. Determine a path whose average power is lower than a set threshold as an virtual path.

The virtual path is generated by interference and noise in the channel environment, and is sudden. Therefore, the average power of the virtual path position is generally lower than the average power of other time domain paths. Therefore, a certain gate can be set. The limit value is used to determine the virtual path in the time domain, and the time domain path with the power below the threshold is determined as the virtual path.

Among them, the set threshold is the power threshold, which can be set according to specific needs. For example: It is set according to the noise power of each path in the time domain.

5105. Remove a channel response of the virtual path in the second channel response to obtain a third channel response. After the virtual path is determined, the corresponding channel response of the virtual path may be set to 0 in the second channel response, that is, the channel response of the virtual path is removed in the second channel response, and the third channel port response is obtained. .

5106. Transform the third channel response into the frequency domain to obtain a fourth channel response of the reference signal. For the third channel response in the time domain of the reference signal obtained by removing the virtual path channel response, the receiving end can further transform it into the frequency domain to obtain a fourth channel response.

In the embodiment of the present invention, a channel estimation process of a reference signal is provided, and the receiving end can generally obtain a channel response of the data signal according to a channel response of the reference signal. For example, the receiving end may interpolate the fourth channel response of the reference signal in the frequency domain according to the position where the transmitting end sends the reference signal and the data signal, to obtain the channel response of the data signal. Further, the received data signal can be subjected to equalization demodulation processing using the channel response of the data signal.

The channel estimation method provided in this embodiment obtains the channel response of the reference signal in the time domain, filters the power delay spectrum of each path in the time domain to obtain the average power of each path, and then sets the average power to a path lower than the set threshold. It is determined to be a virtual path, and the channel response of the virtual path is removed in the channel response in the time domain, and the accuracy of the channel estimation is improved. FIG. 2 is a flowchart of still another embodiment of a channel estimation method according to the present invention. As shown in FIG. 2, the method includes:

5201. Perform channel estimation on the received reference signal, and obtain a first channel response of the reference signal in the frequency domain.

5202. Transform the first channel response into the time domain to obtain a second channel response of the reference signal in the time domain.

For the specific process of S201 and S202, refer to related descriptions of S101 and S102 in the embodiment shown in FIG. 1, and details are not described herein again. 5203. Measure the maximum delay range of each path in the time domain.

When the delay of the path in the time domain reaches a certain value, it indicates that the interference noise on the path is strong, and the useful reference signal cannot be transmitted. Accordingly, the noise reduction process can be performed in the process of performing channel estimation on the reference signal. The receiving end can measure the power of each path in the time domain by using various existing methods, for example: a certain power threshold can be set, and the delay range corresponding to the path whose power value is lower than the set threshold can be determined. For the maximum delay range. As shown in Figure 3, the abscissa is the delay of each path in the time domain, and the ordinate is the power of each path in the time domain. The maximum delay range measured is in the range. And between, among them. ^≥0 , and. ^≤ .

5204. In the second channel response, remove the channel interface of all the paths corresponding to the maximum delay range.

In order to perform noise reduction processing on the channel response of the reference signal, the channel response of all paths corresponding to the maximum delay range may be set to 0 in the second channel response, that is:

r(n) = 0 T _a < n < T _b

5205. Calculate a normalized power delay language of a current subframe of each receiving antenna.

Where is the subframe number, which is the average noise interference power of the time domain channel, and the average noise interference power can be obtained by measurement; ^(") is the second channel response, which is the sequence number of the receiving antenna, which is the subframe number, ^τ . And two endpoints of the maximum delay range of each path in the time domain, respectively

3⁄4 ^{≥ 0} , and ^≤ , η = ϋ, \, · · · , Ν _σΡΤ —\ , W _FFr is the number of points of the inverse Fourier transform performed by transforming the first channel response into the time domain.

5206. Determine an average value of the normalized power delay spectrum of each receiving antenna, that is, a power delay spectrum of each path in the time domain is a normalized power delay spectrum of the current subframe received on each receiving antenna. average value. 1

(«) =— K∑Λ ^Γ («)

r=o According to ^A " ^R "-. ^{Pk n} , the average value of the normalized power delay words of the current subframe of each receiving antenna is obtained, and R is the total number of receiving antennas.

Among them, S206 is a feasible implementation manner, and in order to simplify the steps of S206, it is also possible to average only the normalized power delay spectrum in the subset of receiving antennas.

S207. Perform an alpha on an average value of a normalized power delay spectrum of a current subframe of each antenna.

(alpha) filtering yields the average power W of each path in the time domain.

Filtering the power delay words of each path in the time domain; where A is the subframe number, "is the filtering factor, and is the power delay spectrum of each path in the time domain," = G, l, '", W _FFr _l , the number of points of the inverse Fourier transform performed to transform the first channel response into the time domain.

Optionally, "You can use 1/16 or l/(k+l). You can also choose other values according to your specific needs.

It should be noted that the Alpha filter can also be restarted according to a predetermined rule, for example: When k=T-l, the alpha filter is restarted, and k=0 is restored, and T can be a preset maximum number of filtering times.

5208. Determine a path whose average power is lower than a set threshold as an virtual path.

S209. Remove the channel response of the virtual path in the second channel response of all path channel responses corresponding to the maximum delay range to obtain a third channel response.

If for all paths "all < ^Thr , the channel response at the position corresponding to the maximum value reserved in the second channel response", the path corresponding to the remaining value of ^ except the maximum value of ^ The channel response is set to 0. Otherwise, the channel response at the position of the path corresponding to ^) ^{< 73⁄4 is} set to 0, and the channel response at the position of the path corresponding to A(") ^{≥ J3⁄4r is} reserved. Where AW is the average power of each path in the filtered time domain, which is the set threshold, n = 0, \, -, N _IFFT -\ ^ is the Fourier inverse of transforming the first channel response into the time domain The number of points to be transformed.

That is, if for all "all satisfy A(") ^<J3⁄4r , then:

Others

K (n) = K (η) p _k (n) ≥ Thr

h ^r (n) = 0 p _k {n)<Thr

Among them, the power threshold Thr can be determined according to actual needs, for example: Can be obtained by using the noise power ^{χ σ2} , = 2.

5210. If the reference signal is discontinuously distributed in the frequency domain, in the third channel response, ^^ ¹ )*^^ zeros are added in the maximum delay range, where ^ indicates that one subcarrier has one reference signal , ^ is an integer greater than 0, the number of points of the Fourier transform performed to transform the first channel response into the time domain.

Specifically: If the reference signal in the frequency domain is not continuously distributed, for example: ^ subcarriers have 1 reference signal (^=1, 2, 3, ...), and the ratio of the reference signal to the total subcarrier is 1. Then you need to interpolate in the time domain to ^ ¹ ie in the " ^{= τ} .~ add ^ ¹ - ¹ ) * ^ ^ zero, get Ι = 0, \,···, Α * Ν through the maximum delay A zero is added to the range to interpolate the frequency domain channel response.

5211. Transform a third channel response into a frequency domain to obtain a fourth channel response of the reference signal. Specifically, the time domain channel after noise reduction and zero padding may be transformed into the frequency domain to obtain a fourth channel response. Further, the fourth channel response may be interpolated to intercept the previous value, = ^*M.

H ^r =FFT(h ^r ) H ^r = H ^r (0 ~ M)

Further, the receiving end may further perform a channel response of the data signal according to the position of the reference signal and the data signal sent by the transmitting end, and then perform the equalization demodulation processing on the received data signal by using the channel response of the data signal.

The channel estimation method provided in this embodiment obtains the channel response of the reference signal in the time domain, performs alpha filtering on the power delay spectrum of each path in the time domain to obtain the average power of each path, and then lowers the average power below the set threshold. The path is determined to be a virtual path, and the channel response of the virtual path is removed in the channel response in the time domain, thereby improving the accuracy of the channel estimation. FIG. 4 is a schematic structural diagram of an embodiment of a channel estimation apparatus according to the present invention. As shown in FIG. 4, the apparatus includes: a first processor 11, a converter 12, and a filter 13;

The first processor 11 is configured to perform channel estimation on the received reference signal, and acquire a first channel response of the reference signal in the frequency domain;

The converter 12 is configured to transform the first channel response into the time domain to obtain a second channel response of the reference signal in the time domain;

a filter 13 is configured to filter power delay words of each path in the time domain to obtain an average power of each path in the time domain;

The first processor 11 is further configured to: determine a path whose average power is lower than a set threshold as a virtual path; remove a channel response of the virtual path in the second channel response, to obtain a third channel response;

The converter 12 is further configured to transform the third channel response into the frequency domain to obtain a fourth channel response of the reference signal.

Optionally, the power delay spectrum formed by the power of each path in the time domain is an average value of the normalized power delay spectrum of the current subframe received on the at least one receiving antenna;

Optionally, the filter 13 can be specifically configured to:

, ≤n≤T _a , T _b ≤n≤N _IFFT - l acquire the current subframe of each receiving antenna The normalized power delay term, where is the second channel response, is the serial number of the receiving antenna, is the subframe number, and ^ is the average noise interference power of the time domain channel. And two endpoints of the maximum delay range of each path in the time domain, respectively. ^≥0 , ^≥0 , and ^≤ , n = 0,\,-,N _IFFT -\ ^ The number of points of the inverse Fourier transform for transforming the first channel response into the time domain; according to ^A " ^R "-. ^{Pk n} , obtaining an average value of the normalized power delay words of the current subframe of each receiving antenna, where R is the total number of receiving antennas.

Optionally, the filter 13 can also be used to:

0

⁰ , filtering the power delay words of each path in the time domain; where A is the subframe number, "is the filtering factor, which is the power delay spectrum of the power of each path in the time domain," = G, l, '" , N _FFr _l, the number of points of the inverse Fourier transform performed to transform the first channel response into the time domain.

Optionally, the first processor 11 may be further configured to: if for all "all A(") ^<J3⁄4r , the channel value corresponding to the path corresponding to the maximum value retained in the second channel response, The path corresponding to the remaining value of ⁿ , except for the maximum value, is set to 0. Otherwise, the channel response at the position of the path corresponding to A^>^{<J3⁄4r is} set to 0, and the reserved ^> ^≥7 ^ Corresponding path "channel response at the location, where A is the sub-frame number, the average power of the path in the time domain, ?3⁄4r is the set threshold," = G,l,'", N _FFr - 1, for The number of points of the inverse Fourier transform performed by the first channel response to the time domain.

Optionally, the first processor 11 is further configured to: if the reference signal is discontinuously distributed in the frequency domain, add, in the third channel response, ^ ¹ ― ¹ ^^ zeros in the maximum delay range, where , indicating that the subcarriers have one reference signal, and ^ is an integer greater than 0, which is the number of points of the Fourier transform performed by transforming the first channel response into the time domain. The channel estimation apparatus provided in this embodiment, corresponding to the channel estimation method provided by the present invention, is an execution device of the channel estimation method, and the specific process of performing the channel estimation method can be referred to the method embodiment shown in FIG. 1 and FIG. I will not repeat them here.

The channel estimation apparatus provided in this embodiment obtains the channel response of the reference signal in the time domain, filters the power delay spectrum of each path in the time domain to obtain the average power of each path, and then sets the average power to a path lower than the set threshold. It is determined to be a virtual path, and the channel response of the virtual path is removed in the channel response in the time domain, and the accuracy of the channel estimation is improved.

FIG. 5 is a schematic structural diagram of an embodiment of a receiver provided by the present invention. As shown in FIG. 5, the receiver may include: a receiver 1, a channel estimation apparatus 2, a second processor 3, and a demodulator 4;

a receiver 1 , configured to receive a reference signal and a data signal;

The channel estimation device 2 is configured to perform channel estimation on the received reference signal, obtain a first channel response of the reference signal in the frequency domain, and transform the first channel response into the time domain to obtain a second channel response of the reference signal in the time domain; Filtering the power delay spectrum of each path in the time domain to obtain the average power of each path in the time domain; determining the path whose average power is lower than the set threshold as the virtual path; and removing the channel response of the virtual path in the second channel response, Obtaining a third channel response; transforming the third channel response into the frequency domain to obtain a fourth channel response of the reference signal;

The second processor 3 is configured to perform a channel response that is worthy of the fourth channel response obtained by the channel estimation device 2 to the data signal;

The demodulator 4 is configured to demodulate the data signal received by the receiver 1 according to the channel response of the data signal.

The receiver provided in this embodiment may be set on the terminal side, or may be set on the base station side, or may be set on the relay station. The channel estimation device involved in the channel estimation method provided by the present invention is an execution device of the channel estimation method. For the specific process of performing the channel estimation method, reference may be made to the method embodiment shown in FIG. 1 and FIG. Let me repeat.

The receiver provided in this embodiment acquires the channel response of the reference signal in the time domain, and is timely. The power delay spectrum of each path in the domain is filtered to obtain the average power of each path, and then the path whose average power is lower than the set threshold is determined as the virtual path, and the channel response of the virtual path is removed in the channel response in the time domain. The reference signal channel response of the channel response for removing the virtual path is used to obtain the channel response of the data signal, which improves the accuracy of the channel estimation, improves the correctness of the data signal demodulation, and improves the performance of the receiver and the performance of the communication system.

One of ordinary skill in the art will appreciate that all or part of the steps to implement the various method embodiments described above can be accomplished by hardware associated with the program instructions. The aforementioned program can be stored in a computer readable storage medium. The program, when executed, performs the steps including the foregoing method embodiments; and the foregoing storage medium includes: a medium that can store program codes, such as a ROM, a RAM, a magnetic disk, or an optical disk.

It should be noted that the above embodiments are merely illustrative of the technical solutions of the present invention, and are not intended to be limiting; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art The technical solutions described in the foregoing embodiments may be modified, or some or all of the technical features may be equivalently replaced; and the modifications or substitutions do not deviate from the technical solutions of the embodiments of the present invention. range.

Claims

Rights request

1. A channel estimation method, characterized by including:

Perform channel estimation on the received reference signal, and obtain the first channel response of the reference signal in the frequency domain;

Transform the first channel response to the time domain to obtain the second channel response of the reference signal in the time domain;

Filter the power delay spectrum of each path in the time domain to obtain the average power of each path in the time domain;

Paths whose average power is lower than the set threshold are determined as virtual paths;

Remove the channel response of the imaginary path from the second channel response to obtain a third channel response; transform the third channel response into the frequency domain to obtain a fourth channel response of the reference signal.

2. The method according to claim 1, characterized in that, the power delay spectrum of each path in the time domain is the average value of the normalized power delay spectrum of the current subframe received on each receiving antenna, so Before filtering the power delay of each path in the time domain, it also includes: According to

, T _b ≤ n ≤ N _IFFT - l obtains the normalized power delay spectrum of the current subframe of each receiving antenna, where is the second channel response, is the serial number of the receiving antenna, and is the subframe The serial number, is the average noise interference power of the time domain channel, . and are respectively the two endpoints of the maximum delay range of each path in the time domain, . ^≥0 , ¾ ^≥0 , and. ^≤ , n = 0,\, - , N _IFFT -\ ^ is the number of points of the inverse Fourier transform performed to transform the first channel response into the time domain; according to ^A " ^R "―. ^{Pk n} , obtain each The average value of the normalized power delay of the current subframe of the receiving antenna, R is the total number of the receiving antennas.

3. The method according to claim 1 or 2, characterized in that filtering the power delay of each path in the time domain includes:

, filter the power delay spectrum of each path in the time domain; where A is the subframe number, " is the filter factor, and is the power delay spectrum of each path in the time domain, " = G, l, '", N _FFr _l , is the number of points in the inverse Fourier transform performed to transform the first channel response into the time domain.

4. The method according to any one of claims 1 to 3, characterized in that determining a path with an average power lower than a set threshold as a virtual path includes:

If " is < for all paths, then the channel response at the path " position corresponding to the maximum value retained in the second channel response will be at the path " position corresponding to the remaining values of " except for the maximum value of The channel response of is set to 0, otherwise, the channel response at the path "corresponding to A^) ^{< 7¾} is set to 0, and the channel response at the path "corresponding to A(") ^{≥ J¾r} is retained, where, is the subframe Serial number, is the average power of the path " in the time domain, is the set threshold, " = 0Λ, · · · , N, - is the inverse Fourier transform performed to transform the first channel response into the time domain Points.

5. The method according to any one of claims 2 to 4, characterized in that, before transforming the third channel response into the frequency domain, it further includes:

If the reference signal is distributed discontinuously in the frequency domain, then in the third channel response, ^ ^ ¹ )*^^ zeros are added within the maximum delay range, where ^ represents that there are ^ subcarriers 1 reference signal, ^ is an integer greater than 0, and is the number of points of the inverse Fourier transform performed to transform the first channel response into the time domain.

6. A channel estimation device, characterized by including:

The first processor is used to perform channel estimation on the received reference signal and obtain the first channel response of the reference signal in the frequency domain;

Converter, used to transform the first channel response into the time domain to obtain the reference signal in Second channel response in the time domain;

Filter, used to filter the power delay spectrum of each path in the time domain to obtain the average power of each path in the time domain;

The first processor is further configured to: determine a path with an average power lower than a set threshold as an imaginary path; remove the channel response of the imaginary path from the second channel response to obtain a third channel response; The converter is also used to transform the third channel response into the frequency domain to obtain the fourth channel response of the reference signal.

7. The device according to claim 6, wherein the power delay spectrum composed of the power of each path in the time domain is the normalized power delay spectrum of the current subframe received on at least one receiving antenna. average value; the filter is specifically used for: according to

The normalized power delay spectrum of the current subframe of each receiving antenna, where is the second channel response, is the serial number of the receiving antenna, is the subframe serial number, ^σ2 is the average noise interference power of the time domain channel, ^ and are respectively the two endpoints of the maximum delay range of each path in the time domain, ^≥Q , ¾ ^≥0 , and. ^≤ , n = 0,\,-,N _IFFT -\^ is the number of points of the inverse Fourier transform performed to transform the first channel response into the time domain; according to ^A " ^R "―. ^{Pk n} , obtain each The average value of the normalized power delay of the current subframe of the receiving antenna, R is the total number of the receiving antennas.

8. The device according to claim 6 or 7, characterized in that,

IA (n) = (l- )xp _k _ _x (n) + xp _k (n) k>0 The filter is specifically used to: According to = ^{k = 0} , calculate the power delay of each path in the time domain Filtering; where, is the subframe number, " is the filter factor, is the power delay spectrum of each path in the time domain, η = 0Λ,···,N! is the process of transforming the first channel response into the time domain The number of points in the inverse Fourier transform.

9. The device according to any one of claims 6 to 8, characterized in that the first processor is specifically configured to: if " is >^{< 7¾} for all paths, respond on the second channel The channel response at the path "position corresponding to the maximum value of (") is retained, and the channel response at the path "position corresponding to the remaining values except the maximum value of A^ is set to 0, otherwise, A^ ^{< J¾r} The channel response at the corresponding path "position" is set to 0, and the channel response at the corresponding path "position" with AW ^{≥ J¾r} is retained, where is the subframe number, is the average power of the path "in the time domain, Thr is the set threshold , " = 0Λ, · · · , N, - is the number of points of the inverse Fourier transform performed to transform the first channel response into the time domain.

10. The device according to any one of claims 7 to 9, characterized in that, the first processor is further configured to: if the reference signal is discontinuously distributed in the frequency domain, in the third channel In the response, ^ ¹ — ¹ )*^^ zeros are added within the maximum delay range, where ^ indicates that the ^ subcarrier has 1 reference signal, ^ is an integer greater than 0, and is the The number of points in the Fourier transform used to transform a channel response into the time domain.

11. A receiver, characterized in that it includes: a receiver, a second processor, a demodulator and a channel estimation device according to any one of claims 6-10;

The receiver is used to receive reference signals and data signals;

The second processor is configured to interpolate the fourth channel response obtained by the channel estimation device to obtain the channel response of the data signal;

The demodulator is configured to demodulate the data signal received by the receiver according to the channel response of the data signal.