CN105337908A - Channel estimation device and method and receiver - Google Patents

Abstract

Embodiments of the invention provide a channel estimation device and method and a receiver. The device comprises: a first estimation unit used for carrying out primary estimation on a channel; a first conversion unit used for carrying out inverse Fourier transform on the primary channel estimation result to obtain a time domain signal; a noise suppression unit used for carrying out noise suppression processing on the time domain signal beyond a preset range, wherein the time domain signals within the preset range comprise a time domain signal with effective power larger than a preset first threshold and a time domain signal with effective power smaller than or equal to the first threshold resulting from noise influence; and a second conversion unit used for carrying out Fourier transform on the time domain signal after the noise suppression processing to obtain channel frequency domain response. Since useful signals which may be deemed as noise by mistake within the preset range are protected from being suppressed, the accuracy of channel estimation can be improved, and thus the system performance can be effectively improved.

Description

Channel estimation device, method and receiver

Technical Field

The present invention relates to the field of communications technologies, and in particular, to a channel estimation apparatus and method, and a receiver.

Background

A Long Term Evolution (LTE) system is a new generation broadband wireless communication system based on Orthogonal Frequency Division Multiplexing (OFDM) and Multiple-input Multiple-Output (MIMO) technologies. In a multi-carrier system defined by a physical layer of an LTE system, at a signal receiving end, receiving information under a broadband frequency selective channel is distributed to frequency sub-carriers (subcarriers) which are approximately steadily faded for transmission, so that the influence of frequency selectivity on LTE system performance indexes such as load, coverage capacity and the like is avoided. It can be seen that the accuracy of channel estimation for each subcarrier directly affects the performance of system demodulation.

At present, there are channel estimation methods under various frequency selective channels, wherein, according to the characteristic that a time domain channel is an impulse response, a method of performing noise suppression in the time domain is widely applied. The method comprises the steps of firstly transforming frequency domain Zero-forcing (ZF) channel estimation to a time domain for noise suppression, and then transforming the frequency domain to obtain a final channel estimation value. Compared with the common ZF channel estimation, the system performance is obviously improved.

It should be noted that the above background description is only for the sake of clarity and complete description of the technical solutions of the present invention and for the understanding of those skilled in the art. Such solutions are not considered to be known to the person skilled in the art merely because they have been set forth in the background section of the invention.

Disclosure of Invention

When channel estimation is performed by the above-described conventional channel estimation method, in a case where a signal to noise ratio (SNR) of a signal is low and noise is high, a useful signal may be buried in a background noise signal, so that the useful signal may be erroneously identified as noise and suppressed. In this case, not only may the system performance not obtain a gain, but it may even cause a degradation in the system performance.

Embodiments of the present invention provide a channel estimation apparatus and method, and a receiver, which can improve accuracy of channel estimation by protecting a useful signal, which may be mistaken for noise, within a predetermined range from being suppressed, so as to effectively improve system performance.

According to a first aspect of the embodiments of the present invention, there is provided a channel estimation apparatus, the apparatus including: a first estimation unit, configured to perform preliminary estimation on a channel; the first transformation unit is used for carrying out inverse Fourier transformation according to the result of the channel preliminary estimation to obtain a time domain signal; the noise suppression device comprises a noise suppression unit, a processing unit and a processing unit, wherein the noise suppression unit is used for performing noise suppression processing on time domain signals outside a predetermined range, and the time domain signals inside the predetermined range comprise time domain signals with effective power larger than a preset first threshold and time domain signals with effective power smaller than or equal to the first threshold due to the influence of noise; and the second transformation unit is used for carrying out Fourier transformation on the time domain signal subjected to the noise suppression processing to obtain channel frequency domain response.

According to a second aspect of the embodiments of the present invention, there is provided a receiver, which includes the channel estimation apparatus according to the first aspect of the embodiments of the present invention.

According to a third aspect of the embodiments of the present invention, there is provided a channel estimation method, the method including: performing preliminary estimation on a channel; performing inverse Fourier transform according to the result of the channel preliminary estimation to obtain a time domain signal; carrying out noise suppression processing on time domain signals outside a predetermined range, wherein the time domain signals inside the predetermined range comprise time domain signals with effective power larger than a preset first threshold value and time domain signals with effective power smaller than or equal to the first threshold value due to the influence of noise; and carrying out Fourier transform on the time domain signal subjected to the noise suppression processing to obtain channel frequency domain response.

The invention has the beneficial effects that: by protecting the useful signals which are possibly mistaken for noise within the preset range from being inhibited, the accuracy of channel estimation is improved, and the performance of the system is effectively improved.

Specific embodiments of the present invention are disclosed in detail with reference to the following description and drawings, indicating the manner in which the principles of the invention may be employed. It should be understood that the embodiments of the invention are not so limited in scope. The embodiments of the invention include many variations, modifications and equivalents within the spirit and scope of the appended claims.

Features that are described and/or illustrated with respect to one embodiment may be used in the same way or in a similar way in one or more other embodiments, in combination with or instead of the features of the other embodiments.

It should be emphasized that the term "comprises/comprising" when used herein, is taken to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps or components.

Drawings

The accompanying drawings, which are included to provide a further understanding of the embodiments of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention. It is obvious that the drawings in the following description are only some embodiments of the invention, and that for a person skilled in the art, other drawings can be derived from them without inventive effort. In the drawings:

fig. 1 is a schematic structural diagram of a channel estimation device according to embodiment 1 of the present invention;

fig. 2 is a flowchart of a channel estimation method of embodiment 1 of the present invention;

fig. 3 is a schematic structural diagram of a range determination unit of embodiment 1 of the present invention;

fig. 4 is a flowchart of a method for determining the parameter of the predetermined range according to the effective power of the time-domain signal in the propagation mode according to embodiment 1 of the present invention;

FIG. 5 is a schematic view of a configuration of a parameter determination unit according to embodiment 1 of the present invention;

FIG. 6 is a flowchart of a method for determining a predetermined range parameter according to the effective power of the time domain signal according to embodiment 1 of the present invention;

fig. 7 is a diagram showing the effective power and the predetermined range of the time domain signal of embodiment 1 of the present invention;

FIG. 8 is another schematic diagram of the configuration of a parameter determination unit according to embodiment 1 of the present invention;

FIG. 9 is a flowchart of another method for determining a predetermined range parameter according to the effective power of the time domain signal in embodiment 1 of the present invention;

fig. 10 is a schematic diagram of a structure of a receiver of embodiment 2 of the present invention;

fig. 11 is a schematic block diagram of a system configuration of a receiver of embodiment 2 of the present invention.

Detailed Description

The foregoing and other features of the invention will become apparent from the following description taken in conjunction with the accompanying drawings. In the description and drawings, particular embodiments of the invention have been disclosed in detail as being indicative of some of the embodiments in which the principles of the invention may be employed, it being understood that the invention is not limited to the embodiments described, but, on the contrary, is intended to cover all modifications, variations, and equivalents falling within the scope of the appended claims.

Example 1

Fig. 1 is a schematic structural diagram of a channel estimation device according to embodiment 1 of the present invention. As shown in fig. 1, the apparatus 100 includes: a first estimation unit 101, a first transformation unit 102, a noise suppression unit 103, and a second transformation unit 104, wherein,

the first estimation unit 101 is configured to perform preliminary estimation on a channel;

the first transforming unit 102 is configured to perform inverse fourier transform on the result of the preliminary estimation to obtain a time-domain signal;

the noise suppression unit 103 is configured to perform noise suppression processing on time domain signals outside a predetermined range, where the time domain signals inside the predetermined range include time domain signals with effective power greater than a preset first threshold and time domain signals with effective power less than or equal to the first threshold due to the influence of noise;

the second transforming unit 104 is configured to perform fourier transform on the time domain signal after the noise suppression processing, so as to obtain a channel frequency domain response.

Fig. 2 is a flowchart of a channel estimation method according to embodiment 1 of the present invention. As shown in fig. 2, the method includes:

step 201: performing preliminary estimation on a channel;

step 202: carrying out inverse Fourier transform on the result of the channel preliminary estimation to obtain a time domain signal;

step 203: carrying out noise suppression processing on time domain signals outside a predetermined range, wherein the time domain signals inside the predetermined range comprise time domain signals with effective power larger than a preset first threshold value and time domain signals with effective power smaller than or equal to the first threshold value due to the influence of noise;

step 204: and carrying out Fourier transform on the time domain signal subjected to the noise suppression processing to obtain channel frequency domain response.

As can be seen from the above embodiments, by protecting the useful signal within the predetermined range, which may be mistakenly regarded as noise, from being suppressed, the accuracy of channel estimation can be improved, and thus the performance of the system can be effectively improved.

In the present embodiment, the first estimation unit 101 performs preliminary channel estimation based on the frequency domain signal. Since the signal directly received by the receiving end of the system is a time domain signal, the received time domain signal needs to be subjected to fourier transform processing to obtain a corresponding frequency domain signal.

Thus, the channel estimation apparatus 100 may further include a signal receiving unit for receiving a signal from a transmitting end and a signal processing unit (not shown in the figure); the signal processing unit is used for carrying out Fourier transform processing on the received signals so as to obtain corresponding frequency domain signals.

In the present embodiment, the signal receiving unit and the signal processing unit are optional components. For example, when the channel estimation apparatus 100 is applied to a receiver, the reception and fourier transform processing of the signal may be implemented by other components of the receiver.

In the present embodiment, the channel may be preliminarily estimated using any one of the existing methods. The method for performing preliminary channel estimation according to the present embodiment is exemplarily described below.

For example, the frequency domain signal y received by the first estimation unit 101 may be preliminarily estimated using a Zero-forcing (ZF) channel estimation method. Wherein, assuming that X is a reference signal known by the receiving end, the ZF channel estimation value h of the reference signal_ZFCan be represented by the following formula (1):

$h_{\mathrm{ZF}}=X^{-1}-y={\left[\begin{array}{cccc}{h}_{\mathrm{ZF}}\left(0\right)& H_{\mathrm{ZF}}\left(1\right)& ...& H_{\mathrm{ZF}}(N_c-1)\end{array}\right]}^T\∈C^{N_c\×1}---\left(1\right)$

wherein, X^-1An inverse matrix, N, representing the reference signal X_cThe number of subcarriers included for the bandwidth of the receiver.]^TRepresenting a matrix transpose operation.

In this embodiment, as shown in fig. 1, the channel estimation apparatus 100 may further include an interpolation unit 105, wherein the interpolation unit 105 is configured to perform interpolation processing on the result of the channel preliminary estimation, and supply the result of the interpolation processing to the first transformation unit 102 for the inverse fourier transformation.

In the present embodiment, the interpolation unit 105 is an optional component, and is indicated by a dashed box in fig. 1.

The result of the initial channel estimation is expanded into a continuous signal by performing difference processing on the result of the initial channel estimation, so that the accuracy of the channel estimation can be further improved.

In the present embodiment, the result of the channel preliminary estimation may be interpolated using any existing method. E.g. at ZF channel estimate h_ZFAfter insert one (N)_fft-N_c) × 1 long vector, making ZF channel estimate h_ZFExtension to N_fft× 1 vector h_IPThen the interpolated channel estimation vector h_IPCan be represented by the following formula (2):

$h_{\mathrm{IP}}={\left[\begin{array}{cc}{h}_{\mathrm{ZF}}^T& h_{\mathrm{VCFR}}^T\end{array}\right]}^T\∈C^{N_{\mathrm{fft}}\×1}---\left(2\right)$

wherein N is_fftFor the second conversion unit 104Number of points of line Fourier transform, N_cNumber of subcarriers included for the bandwidth of the receiver, N_fft≥N_c，Represents the inserted vector, which is called virtual channel frequency domain response (VCFR).

In this embodiment, the interpolation processing may be performed in a linear manner or a nonlinear manner, and the embodiment of the present invention does not limit the specific manner of the interpolation processing. The following describes exemplary methods of performing difference processing in a linear manner and a nonlinear manner in the present embodiment.

For example, when interpolation processing is performed using a linear method, the purpose is to add a virtual channel frequency domain response h_VCFRThe latter frequency domain waveform is a continuous periodic signal, and can be represented by the following formula (3):

$h_{\mathrm{VCFR}}\left(k\right)=\frac{h_{\mathrm{ZF}}\left(0\right)-h_{\mathrm{ZF}}(N_c-1)}{N_{\mathrm{fft}}-N_c+2}.(k-N_c+2)+h_{\mathrm{ZF}}(N_c-1)---\left(3\right)$

wherein h is_VCFR(k) Represents the frequency domain signal at k after interpolation, k ∈ [ N [ ]_c,N_fft-1]，N_fftNumber of points for FFT, N_cThe number of subcarriers included in the bandwidth of the receiver.

For example, when interpolation processing is performed using a nonlinear method, the purpose is to add a virtual channel frequency domain response h_VCFRThe frequency domain waveform is a smooth and continuous periodic signal, and can be represented by the following formula (4):

$h_{\mathrm{VCFR}}\left(k\right)=\frac{1}{2}(1+\cos \left(\frac{\mathrm{\π}(k-N_c+1)}{L}\right))\·\mathrm{\θ}\left(\frac{k-N_c+1}{L}\right)\·F\left(k\right)+\frac{1}{2}(1+\cos \frac{\mathrm{\π}(k-N_{\mathrm{fft}})}{L})\·\mathrm{\θ}\left(\frac{k-N_{\mathrm{fft}}}{L}\right)\·G\left(k\right)$

$\mathrm{\θ}\left(t\right)=\left\{\begin{array}{c}1,\left|t\right|\≤1\\ 0,\left|t\right|>1\end{array}\right.---\left(4\right)$

wherein h is_VCFR(k) Represents the frequency domain signal at k after interpolation, k ∈ [ N [ ]_c,N_fft-1]，N_cNumber of subcarriers included for the bandwidth of the receiver, N_fftThe number of points in Fourier transform, F (k) and G (k) respectively represent the ZF channel estimation value h_ZFIn subcarrier N_cTangential line segments at 1 and 0, L represents the length of the tangential line segment, and 2 ≦ L ≦ (N)_fft-N_c)/2。

Wherein F (k) and G (k) can be represented by the following formula (5):

F(k)＝(k-N_c+1)a+b

(5)

G(k)＝(k-N_fft)c+d

wherein, k ∈ [ N ]_c,N_fft-1]，N_fftNumber of points for FFT, N_cThe number of subcarriers included in the bandwidth of the receiver;

wherein a, b, c, d can be calculated according to the following formula (6):

$a=\frac{1}{N_{\mathrm{est}}}\underset{i=N_c-N_{\mathrm{esi}}}{\overset{N_c-1}{\mathrm{\Σ}}}(h_{\mathrm{ZF}}\left(i\right)-h_{\mathrm{ZF}}(i-1)),$

$b=\frac{1}{N_{\mathrm{est}}}\underset{i=N_c-N_{\mathrm{esi}}}{\overset{N_c-1}{\mathrm{\Σ}}}{h}_{\mathrm{ZF}}\left(i\right)+\frac{(N_{\mathrm{est}}-1)}{2}a,---\left(6\right)$

$c=\frac{1}{N_{\mathrm{est}}}\underset{i=0}{\overset{N_{\mathrm{esi}}-1}{\mathrm{\Σ}}}(h_{\mathrm{ZF}}(i+1)-h_{\mathrm{ZF}}\left(i\right)),$

$d=\frac{1}{N_{\mathrm{est}}}\underset{i=0}{\overset{N_{\mathrm{esi}}-1}{\mathrm{\Σ}}}{h}_{\mathrm{ZF}}\left(i\right)\frac{(N_{\mathrm{est}}-1)}{2}c$

wherein N is_estNumber of subcarriers near the edge, N_cThe number of subcarriers included in the bandwidth of the receiver.

In the present embodiment, after the result subjected to the interpolation processing is obtained, the result subjected to the interpolation processing may be subjected to inverse fourier transform using any of the existing methods, thereby obtaining a time-domain signal.

For example, Inverse Fast Fourier Transformation (IFFT) may be used for Inverse fourier transformation to obtain a time domain signal represented by the following formula (7):

$g_{\mathrm{IP}}=\frac{1}{N_{\mathrm{fft}}}{F}^H{h}_{\mathrm{IP}}---\left(7\right)$

wherein, g_IPDenotes the Channel Impulse Response (CIR) in the time domain without noise suppression processing, and g_IPSatisfy the requirement of $g_{\mathrm{IP}}={\left[\begin{array}{cccc}{g}_{\mathrm{IP}}\left(0\right)& g_{\mathrm{IP}}\left(1\right)& ...& g_{\mathrm{IP}}(N_{\mathrm{fft}}-1)\end{array}\right]}^T\∈C^{N_{\mathrm{fft}}\×1},$ F represents an FFT transformation matrix, [.]^HRepresenting a matrix conjugate transpose operation.

In this embodiment, after obtaining the time domain signals, the noise suppression unit 103 performs noise suppression processing on the time domain signals outside the predetermined range, where the time domain signals inside the predetermined range include the time domain signals whose effective power is greater than a preset first threshold and the time domain signals whose effective power is less than or equal to the first threshold due to the influence of noise.

In the present embodiment, the effective power of the time domain signal refers to the signal power after the transmission signal is affected by noise or other factors.

In the present embodiment, the noise suppression processing may be performed on the time domain signal outside the predetermined range using any one of the existing methods. For example, the time-domain signal may be subjected to noise suppression processing using the following equation (8):

wherein, g_NS(l) Representing the time-domain signal at the location l after the noise suppression process, g_IP(l) Representing the time-domain signal at location l without noise suppression, A_IP(l) Representing the power, T, of the time-domain signal at position l_nocDenotes a first threshold value, N_startIndicating a starting position of a predetermined range, L_wIndicating the length of a predetermined range, N_fftNumber of points representing Fourier transform, l is more than or equal to 0 and less than or equal to N_fft-1。

In this embodiment, the signal is randomly faded or when the signal-to-noise ratio is lowIt may happen that the power of the useful signal is below T due to the influence of noise_nocIn the case where the signal is mistaken for noise, the noise suppression processing is performed only on the time domain signal outside the predetermined range, so that the useful signal within the predetermined range, which may be mistaken for noise, can be protected from being suppressed.

In this embodiment, the channel estimation apparatus 100 may further include a range determination unit 106, where the range determination unit 106 is configured to select a propagation mode according to the time delay of the time domain signal obtained through the inverse fourier transform, and determine a parameter of the predetermined range, where the parameter of the predetermined range includes a start position of the predetermined range and a length of the predetermined range.

In the present embodiment, the range determination unit 106 is an optional component, and is indicated by a dashed box in fig. 1.

In this embodiment, the range determining unit 106 may determine the parameter of the predetermined range by using any existing method according to the delay selection propagation mode of the time domain signal. The following exemplarily explains the structure of the range determining unit 106 of the present embodiment and a method of determining a parameter of the predetermined range.

Fig. 3 is a schematic structural diagram of the range determining unit of the present embodiment. As shown in fig. 3, the range determining unit 106 includes a second estimating unit 301, a mode selecting unit 302, and a parameter determining unit 303, wherein,

the second estimating unit 301 is configured to estimate delay spread according to the multipath delay of the time domain signal;

the mode selection unit 302 is configured to select a corresponding propagation mode according to the estimated delay spread, and obtain a time domain signal in the propagation mode;

the parameter determining unit 303 is configured to determine the parameter of the predetermined range according to the effective power of the time-domain signal in the propagation mode.

Fig. 4 is a flowchart of a method for determining the parameter of the predetermined range according to the effective power of the time-domain signal in the propagation mode according to the embodiment. As shown in fig. 4, the method includes:

step 401: estimating the time delay expansion according to the multipath time delay of the time domain signal;

step 402: selecting a corresponding propagation mode according to the estimated time delay expansion to obtain a time domain signal in the propagation mode;

step 403: the predetermined range of parameters is determined based on the effective power of the time domain signal in the propagation mode.

In this embodiment, any conventional method may be used to estimate the delay spread according to the multipath delay of the time domain signal. The method for estimating the delay spread according to the multipath delay of the time domain signal according to the present embodiment is exemplarily described below.

For example, the estimation of the delay spread may be performed based on the manner in which the delay spread is defined.

The number of fading multipath is assumed to be M, wherein M 'time delay multipath with the highest signal strength is obtained by any existing method, and M' is less than or equal to M. For example, the M' delay multipaths with the highest signal strength may be obtained by using an eigenvalue decomposition (EVD) method or a method of performing screening by setting a threshold value.

According to the definition of the delay spread, the delay spread tau_rmsCan be represented by the following formula (9):

${\mathrm{\τ}}_{\mathrm{rms}}=\sqrt{\frac{\underset{m=0}{\overset{M^{\′}-1}{\mathrm{\Σ}}}{({{\mathrm{\τ}}^{\′}}_m-\stackrel{\‾}{\mathrm{\τ}})}^2{\left|{{\mathrm{\γ}}^{\′}}_m\right|}^2}{\underset{m=0}{\overset{M^{\′}-1}{\mathrm{\Σ}}}{\left|{{\mathrm{\γ}}^{\′}}_m\right|}^2}}---\left(9\right)$

wherein, tau'_mAnd gamma'_mRepresenting the delay value and amplitude value of the mth fading multipath,denotes the mean delay, M is 0,1, …, M'.

And, the time delay mean value thereinCan be represented by the following formula (10):

$\stackrel{\‾}{\mathrm{\τ}}=\sqrt{\frac{\underset{m=0}{\overset{M^{\′}-1}{\mathrm{\Σ}}}{{\mathrm{\τ}}^{\′}}_m{\left|{{\mathrm{\γ}}^{\′}}_m\right|}^2}{\underset{m=0}{\overset{M^{\′}-1}{\mathrm{\Σ}}}{\left|{{\mathrm{\γ}}^{\′}}_m\right|}^2}}---\left(10\right)$

wherein, tau'_m，γ'_mAnd τ_m，γ_mNot necessarily equal.

The estimation of the delay spread may also be performed based on minimum delay, for example.

Similarly, the number of fading multipath is assumed to be M, wherein M 'time delay multipath with the highest signal strength is obtained by any existing method, and M' is less than or equal to M. In addition, assuming that each multipath is arranged in ascending order of time delay, it can be expressed by the following equation (11):

τ'₀≤τ'₁≤...≤τ'_M'-1(11)

wherein, tau'_M'-1Representing the delay value of the M' -1 th fading multipath.

Assuming a delay spread τ_rmsIs equal to the maximum delay, thereby obtaining a delay spread τ expressed by the following equation (12)_rms：

τ_rms＝τ'_M'-1(12)

In this embodiment, after obtaining the estimated delay spread, a corresponding propagation mode may be selected according to the estimated delay spread, and a time domain signal in the propagation mode is obtained. Here, the propagation mode corresponding to the delay spread may be selected using any of the existing methods. The selection of the transmission mode represented by the different transmission channel models can be made, for example, by means of a table look-up.

Table 1 is a table of propagation modes corresponding to estimated delay spreads of the present embodiment. As shown in table 1, there is a corresponding propagation mode for a range of delay spreads. For example, when the estimated delay spread is 0.5 μ s, then the corresponding EVA propagation mode is selected.

The EPA, EVA and ETU in table 1 are transport channel models widely used in receivers defined in 3GPP standards TS36.101 [ 3 ] and TS36.104 [ 4 ], but the embodiments of the present invention are not limited to these three transport channel models. In addition, the range of the delay spread corresponding to each propagation mode in table 1 is set according to actual needs, and the embodiment of the present invention is not limited to the specific limitation on the delay spread in table 1.

TABLE 1

Delay spread taurms(μs)	0～0.1	0.1～1	>1
				Transmission channel model	EPA	EVA	ETU

In this embodiment, after the corresponding transmission channel model is selected, the delay corresponding to each transmission channel model is determinedSum amplitudeIt is known that, in conjunction with equation (2) above, a time domain signal corresponding to the transmission channel model is obtained, which is represented by equation (13) below:

$g_{\mathrm{IP}}^{\det }\left(l\right)=g_{\mathrm{ZF}}^{\det }\left(l\right)+g_{\mathrm{VCFR}}^{\det }\left(l\right)---\left(13\right)$

wherein,representing the time domain signal at the location/corresponding to the transmission channel model,andcan be calculated using the following formula (14):

$g_{\mathrm{ZF}}^{\det }\left(l\right)=\frac{1}{N_{\mathrm{fft}}}\underset{m=0}{\overset{M-1}{\mathrm{\Σ}}}{\mathrm{\γ}}_m^{\det }\frac{1-e^{j2\mathrm{\π}({\mathrm{\Δf\τ}}_m^{\det }-l/N_{\mathrm{fft}})N_c}}{1-e^{j2\mathrm{\π}}({\mathrm{\Δf\τ}}_m^{\det }-l/N_{\mathrm{fft}})}$

$g_{\mathrm{VCFR}}^{\det }\left(l\right)=\frac{1}{N_{\mathrm{fft}}}\underset{k=0}{\overset{N_{\mathrm{fft}}-N_c-1}{\mathrm{\Σ}}}{e}^{-j2\mathrm{\πl}(k+N_c)/N_{\mathrm{fft}}}\·h_{\mathrm{VCFR}}^{\det }\left(k\right)---\left(14\right)$

wherein,andrespectively, the time delay and amplitude corresponding to the transmission channel model, k ∈ [ N [ ]_c,N_fft-1]，N_fftNumber of points for FFT, N_cThe number of subcarriers included in the bandwidth of the receiver, af denotes the interval of each subcarrier, M is the number of fading multipaths,representing the frequency domain signal at k with difference processing corresponding to the transmission channel model.

After obtaining the time domain signal corresponding to the transmission modeThe effective power of the time domain signal may then be obtained according to any of the existing methods. For example, it can be calculated using the following formula (15):

$A_{\mathrm{IP}}^{\det }\left(l\right)=20\·{\log }_{10}\left|g_{\mathrm{IP}}^{\det }\left(l\right)\right|---\left(15\right)$

wherein,representing the time domain signal at the location/corresponding to the transmission channel model,representing time domain signalsThe effective power of (a).

In the present embodiment, after obtaining the time-domain signal in the propagation mode, the parameter determining unit 303 determines the parameter of the predetermined range according to the effective power of the time-domain signal. Wherein the predetermined range of parameters may be determined from the effective power of the time domain signal using any one of the existing methods. The structure of the parameter determination unit 303 of the present embodiment and a method of determining the predetermined range parameter are exemplarily described below.

Fig. 5 is a schematic structural diagram of the parameter determination unit of the present embodiment. As shown in fig. 5, the parameter determining unit 303 includes a first determining unit 501 and a second determining unit 502, wherein,

the first determination unit 501 is configured to take a position satisfying the following condition as a start position of the predetermined range: the effective power of the time domain signal at the position is greater than or equal to a preset second threshold value, the effective power at the position next to the position is smaller than the second threshold value, and the effective powers of the time domain signal at the position and the position next to the position are both in a descending trend, wherein the second threshold value is smaller than the first threshold value;

the second determining unit 502 is configured to determine the length of the predetermined range according to the starting position.

Fig. 6 is a flowchart of a method for determining a predetermined range parameter according to the effective power of the time domain signal according to the embodiment. As shown in fig. 6, the method includes:

step 601: the position satisfying the following condition is taken as the starting position of the predetermined range: the effective power of the time domain signal at the position is greater than or equal to a preset second threshold value, the effective power at the position next to the position is smaller than the second threshold value, and the effective powers of the time domain signal at the position and the position next to the position are both in a descending trend, wherein the second threshold value is smaller than the first threshold value;

step 602: the length of the predetermined range is determined based on the starting position.

In the present embodiment, the start position and the length of the predetermined range may be determined using any existing method. For example, the starting position N of the predetermined range_startCan be obtained according to the following method:

wherein,representing time domain signalsThe effective power of the power converter, $\mathrm{\β}\left(l\right)=A_{\mathrm{IP}}^{\det }(l+1)-A_{\mathrm{IP}}^{\det }\left(l\right),$ which represents the effective power curveSlope value at point l, T_startThe second threshold value is a preset second threshold value, and the second threshold value can be set according to actual needs, and is smaller than the first threshold value.

At a start position N where the predetermined range is obtained_startThen, the length L of the predetermined range_wCan be obtained according to the following method:

wherein N is_fftRepresenting the number of points of the fourier transform.

Fig. 7 is a schematic diagram of the effective power and the predetermined range of the time domain signal of the present embodiment. As shown in fig. 7, from a start position N_startThe range within the starting dashed box represents the predetermined range, i.e., the noise suppression processing is performed on the time domain signal outside the dashed box.

In this embodiment, the parameter determining unit 303 may have other structures, and may determine the predetermined range parameter by other methods. Another structure of the parameter determination unit of the present embodiment and another method of determining the predetermined range parameter are exemplarily described below.

Fig. 8 is another schematic structural diagram of the parameter determination unit of the present embodiment. As shown in fig. 8, the parameter determination unit 303 includes a third determination unit 801 and a fourth determination unit 802, wherein,

the third determining unit 801 is configured to determine a starting position of the predetermined range according to the estimated delay spread and a duration of an ofdm symbol;

the fourth determination unit 802 is configured to take the distance between the start position and the origin as the length of the predetermined range.

Fig. 9 is a flowchart of another method for determining a predetermined range parameter according to the effective power of the time domain signal according to the embodiment. As shown in fig. 9, the method includes:

step 901: determining the starting position of the predetermined range according to the estimated delay spread and the duration of an orthogonal frequency division multiplexing symbol;

step 902: the distance from the start position to the origin is taken as the length of the predetermined range.

In the present embodiment, the start position of the predetermined range may be determined using any existing method. For example, the starting position N of the predetermined range_startCan be obtained by the following formula (16):

wherein, t_durationRepresents the duration, τ, of an Orthogonal Frequency Division Multiplexing (OFDM) symbol_rmsRepresenting the delay spread, N_fftRepresenting the number of points of the fourier transform.

In the method, a starting position N of a predetermined range is determined_startThe starting position N can then be determined_startThe distance from the origin is taken as the length L of the predetermined range_w。

In this embodiment, after the noise suppression unit 103 performs noise suppression processing on the time domain signal outside the predetermined range, the second transformation unit 104 performs fourier transformation on the time domain signal after the noise suppression processing to obtain a channel frequency domain response.

In the present embodiment, the time-domain signal after the noise suppression processing may be fourier-transformed by any of the conventional methods. For example, the time-domain signal after the noise suppression processing may be fourier-transformed using a Fast Fourier Transform (FFT) method, and the obtained result may be represented by the following formula (17):

h_NS＝Fg_NS(17)

wherein h is_NSWhich is indicative of the frequency response of the channel, $g_{\mathrm{NS}}={\left[\begin{array}{cccc}{g}_{\mathrm{NS}}\left(0\right)& g_{\mathrm{NS}}\left(1\right)& ...& g_{\mathrm{NS}}(N_{\mathrm{fft}}-1)\end{array}\right]}^T\∈C^{N_{\mathrm{fft}}\×1},$ f denotes the Fourier transform matrix, N_fftRepresenting the number of points of the fourier transform.

After obtaining the channel frequency response h_NSI.e. after obtaining the result of the channel estimation, the channel frequency response h_NSIs input to the demodulation device 203 of fig. 2 for demodulation of the signal, thereby obtaining a demodulated received signal.

As can be seen from the above embodiments, by protecting the useful signal within the predetermined range, which may be mistakenly regarded as noise, from being suppressed, the accuracy of channel estimation can be improved, and thus the performance of the system can be effectively improved.

Example 2

The embodiment of the invention also provides a receiver. A description will be given of an example of a scenario in which the channel estimation apparatus 100 of embodiment 1 is applied to a receiver in a Frequency Division Duplex (FDD) mode in an LTE system, where reception and fourier transform processing of a signal are performed by the receiver, but the embodiment of the present invention is not limited to the application in this scenario.

Fig. 10 is a schematic diagram of a structure of the receiver of the present embodiment. The receiver includes a fourier transform device 1001, a channel estimation device 1002, and a demodulation device 1003, and the channel estimation device 1002 has the same configuration and function as the channel estimation device 100 in fig. 1. As shown in fig. 10, the received time domain signal is input to a fourier transform deviceFFT processing is performed in a block 1001, and a frequency domain signal y obtained by FFT processing is input to a channel estimation device 1002, and the channel estimation device 1002 performs channel estimation based on the frequency domain signal y and performs a result h of channel estimation_NSInputted to the demodulating means 203, the demodulating means 203 estimates the result h according to the channel_NSThe demodulation of the signal is performed to obtain a demodulated received signal.

In the present embodiment, the frequency domain signal y obtained through the FFT processing can be represented by the following equation (18):

$y=h^{T}X+n\∈C^{1\×N_c}---\left(18\right)$

wherein,a diagonal matrix representing diagonal elements as load information,for the channel frequency domain response (CFR),white gaussian noise with an average value of 0. [.]^TRepresenting a matrix transposition operation, N_cThe number of subcarriers included in the bandwidth of the receiver.

Fig. 11 is a schematic block diagram of a system configuration of a receiver 1100 according to embodiment 2 of the present invention. As shown in fig. 11, receiver 1100 may include a central processor 1101 and a memory 1102; the memory 1102 is coupled to a central processor 1101. The figure is exemplary; other types of structures may also be used in addition to or in place of the structure to implement telecommunications or other functions.

As shown in fig. 11, the receiver 1100 may further include: a communication module 1103, an input unit 1104, a display 1105, and a power supply 1106.

In one embodiment, the functions of the channel estimation apparatus may be integrated into the central processor 1101. Wherein the central processor 1101 may be configured to: performing preliminary estimation on a channel; carrying out inverse Fourier transform on the result of the channel preliminary estimation to obtain a time domain signal; carrying out noise suppression processing on time domain signals outside a predetermined range, wherein the time domain signals inside the predetermined range comprise time domain signals with effective power larger than a preset first threshold value and time domain signals with effective power smaller than or equal to the first threshold value due to the influence of noise; and carrying out Fourier transform on the time domain signal subjected to the noise suppression processing to obtain channel frequency domain response.

Wherein the central processor 1101 may be further configured to: and selecting a propagation mode according to the time delay of the time domain signal obtained through inverse Fourier transform, and determining the parameter of the predetermined range, wherein the parameter of the predetermined range comprises the starting position of the predetermined range and the length of the predetermined range.

Wherein the selecting a propagation mode according to the time delay of the time domain signal to determine a parameter of a predetermined range comprises: estimating the time delay expansion according to the multipath time delay of the time domain signal; selecting a corresponding propagation mode according to the estimated time delay expansion to obtain a time domain signal in the propagation mode; determining the parameter of the predetermined range according to the effective power of the time domain signal in the propagation mode.

Wherein said determining the parameter of the predetermined range from the power of the time domain signal in the propagation mode comprises; taking a position satisfying the following condition as a starting position of the predetermined range: the effective power of the time domain signal at the position is greater than or equal to a preset second threshold, the effective power at the position next to the position is smaller than the second threshold, and the effective powers of the time domain signal at the position and the position next to the position both have a descending trend of change, wherein the second threshold is smaller than the first threshold; and determining the length of the preset range according to the starting position.

Wherein the determining the parameter of the predetermined range according to the time domain signal in the propagation mode may also include: determining the starting position of the predetermined range according to the estimated delay spread and the duration of one orthogonal frequency division multiplexing symbol; and taking the distance between the starting position and the origin as the length of the preset range.

Wherein the central processor 1101 may be further configured to: and carrying out interpolation processing on the result of the channel preliminary estimation, and carrying out the inverse Fourier transform according to the result of the interpolation processing.

In another embodiment, the channel estimation device may be configured separately from the central processor 1101, for example, the channel estimation device may be configured as a chip connected to the central processor 1101, and the function of the channel estimation device is realized by the control of the central processor.

It is not necessary for receiver 1100 to include all of the components shown in fig. 11 in this embodiment either

As shown in fig. 11, the central processor 1101, sometimes referred to as a controller or operational control, may comprise a microprocessor or other processor device and/or logic device, the central processor 1101 receiving inputs and controlling the operation of the various components of the receiver 1100.

The memory 1102, for example, may be one or more of a buffer, a flash memory, a hard drive, a removable media, a volatile memory, a non-volatile memory, or other suitable device. The information relating to the failure may be stored, and a program for executing the information may be stored. And the central processor 1101 may execute the program stored in the memory 1102 to realize information storage or processing, or the like. The functions of other parts are similar to the prior art and are not described in detail here. The various components of receiver 1100 may be implemented in dedicated hardware, firmware, software, or combinations thereof, without departing from the scope of the invention.

As can be seen from the above embodiments, by protecting the useful signal within the predetermined range, which may be mistakenly regarded as noise, from being suppressed, the accuracy of channel estimation can be improved, and thus the performance of the system can be effectively improved.

Example 3

An embodiment of the present invention further provides a channel estimation method, which corresponds to the channel estimation device in embodiment 1, and the channel estimation method can be referred to fig. 2 in embodiment 1. As shown in fig. 2, the method includes:

step 201: performing preliminary estimation on a channel;

step 202: carrying out inverse Fourier transform on the result of the channel preliminary estimation to obtain a time domain signal;

step 203: carrying out noise suppression processing on time domain signals outside a predetermined range, wherein the time domain signals inside the predetermined range comprise time domain signals with effective power larger than a preset first threshold value and time domain signals with effective power smaller than or equal to the first threshold value due to the influence of noise;

step 204: and carrying out Fourier transform on the time domain signal subjected to the noise suppression processing to obtain channel frequency domain response.

In this embodiment, the method of preliminarily estimating the channel, the method of inverse fourier transforming the result of the preliminary estimation of the channel, the method of determining the parameter of the predetermined range, the method of performing the noise suppression processing on the time domain signal outside the predetermined range, and the method of fourier transforming the time domain signal after the noise suppression processing are the same as those described in embodiment 1, and are not repeated here.

As can be seen from the above embodiments, by protecting the useful signal within the predetermined range, which may be mistakenly regarded as noise, from being suppressed, the accuracy of channel estimation can be improved, and thus the performance of the system can be effectively improved.

An embodiment of the present invention also provides a computer-readable program, where when the program is executed in a channel estimation device or a receiver, the program causes a computer to execute the channel estimation method described in embodiment 3 in the channel estimation device or the receiver.

An embodiment of the present invention further provides a storage medium storing a computer-readable program, where the computer-readable program enables a computer to execute the channel estimation method described in embodiment 3 in a channel estimation device or a receiver.

The above devices and methods of the present invention can be implemented by hardware, or can be implemented by hardware and software. The present invention relates to a computer-readable program which, when executed by a logic section, enables the logic section to realize the above-described apparatus or constituent section, or to realize the above-described various methods or steps. The present invention also relates to a storage medium such as a hard disk, a magnetic disk, an optical disk, a DVD, a flash memory, or the like, for storing the above program.

While the invention has been described with reference to specific embodiments, it will be apparent to those skilled in the art that these descriptions are illustrative and not intended to limit the scope of the invention. Various modifications and alterations of this invention will become apparent to those skilled in the art based upon the spirit and principles of this invention, and such modifications and alterations are also within the scope of this invention.

With respect to the embodiments including the above embodiments, the following remarks are also disclosed:

supplementary note 1, a channel estimation apparatus, the apparatus comprising:

a first estimation unit, configured to perform preliminary estimation on a channel;

the first transformation unit is used for carrying out inverse Fourier transformation on the result of the channel preliminary estimation to obtain a time domain signal;

the noise suppression device comprises a noise suppression unit, a processing unit and a processing unit, wherein the noise suppression unit is used for performing noise suppression processing on time domain signals outside a predetermined range, and the time domain signals inside the predetermined range comprise time domain signals with effective power larger than a preset first threshold and time domain signals with effective power smaller than or equal to the first threshold due to the influence of noise;

and the second transformation unit is used for carrying out Fourier transformation on the time domain signal subjected to the noise suppression processing to obtain channel frequency domain response.

Supplementary note 2, the apparatus according to supplementary note 1, wherein the apparatus further comprises:

a range determining unit, configured to select a propagation mode according to the time delay of the time domain signal obtained through the inverse fourier transform, and determine a parameter of the predetermined range, where the parameter of the predetermined range includes a start position of the predetermined range and a length of the predetermined range.

Note 3 that the apparatus according to note 2, wherein the range determining unit includes:

the second estimation unit is used for estimating time delay expansion according to the multipath time delay of the time domain signal;

the mode selection unit is used for selecting a corresponding propagation mode according to the estimated time delay expansion to obtain a time domain signal in the propagation mode;

a parameter determination unit for determining a parameter of the predetermined range from an effective power of the time domain signal in the propagation mode.

Supplementary note 4, the apparatus according to supplementary note 3, wherein, the said parameter determination unit includes;

a first determination unit configured to take a position satisfying a condition as a start position of the predetermined range: the effective power of the time domain signal at the position is greater than or equal to a preset second threshold, the effective power at the position next to the position is smaller than the second threshold, and the effective powers of the time domain signal at the position and the position next to the position both have a descending trend of change, wherein the second threshold is smaller than the first threshold;

a second determining unit for determining the length of the predetermined range according to the start position.

Supplementary note 5, the apparatus according to supplementary note 3, wherein the parameter determination unit includes:

a third determining unit, configured to determine a starting position of the predetermined range according to the estimated delay spread and a duration of an ofdm symbol;

a fourth determination unit for taking a distance of the start position from an origin as a length of the predetermined range.

Supplementary note 6, the apparatus according to supplementary note 1, wherein the noise suppressing unit performs the noise suppressing process using the following formula (1):

$g_{\mathrm{NS}}\left(l\right)=\left\{\begin{array}{c}{g}_{\mathrm{IP}}\left(l\right),\mathrm{if}(A_{\mathrm{IP}}\left(l\right)>T_{\mathrm{noc}})\mathrm{OR}\left[(0\≤l\≤N_{\mathrm{start}})\mathrm{AND}(N_{\mathrm{fft}}-(L_w-N_{\mathrm{start}})\≤l\≤N_{\mathrm{fft}})\right]\\ 0,\mathrm{otherwise}\end{array}\right.---\left(1\right)$

wherein, g_NS(l) To representTime domain signal at location l after noise suppression processing, g_IP(l) Representing the time-domain signal at location l without noise suppression, A_IP(l) Representing the power, T, of the time-domain signal at position l_nocDenotes a first threshold value, N_startIndicating a starting position of a predetermined range, L_wIndicating the length of a predetermined range, N_fftNumber of points representing Fourier transform, l is more than or equal to 0 and less than or equal to N_fft-1。

Supplementary note 7, the apparatus according to supplementary note 1, wherein the apparatus further comprises:

an interpolation unit for performing interpolation processing on a result of the channel preliminary estimation, and supplying a result of the interpolation processing to the first transformation unit for the inverse fourier transformation.

Supplementary note 8, a receiver comprising the channel estimation device according to supplementary note 1.

Supplementary note 9, a channel estimation method, the method comprising:

performing preliminary estimation on a channel;

carrying out inverse Fourier transform on the result of the channel preliminary estimation to obtain a time domain signal;

carrying out noise suppression processing on time domain signals outside a predetermined range, wherein the time domain signals inside the predetermined range comprise time domain signals with effective power larger than a preset first threshold value and time domain signals with effective power smaller than or equal to the first threshold value due to the influence of noise;

and carrying out Fourier transform on the time domain signal subjected to the noise suppression processing to obtain channel frequency domain response.

Supplementary note 10, the method according to supplementary note 9, wherein the method further comprises:

and selecting a propagation mode according to the time delay of the time domain signal obtained through inverse Fourier transform, and determining the parameter of the predetermined range, wherein the parameter of the predetermined range comprises the starting position of the predetermined range and the length of the predetermined range.

Supplementary note 11, the method according to supplementary note 10, wherein the selecting a propagation mode according to the time delay of the time domain signal to determine a parameter of a predetermined range includes:

estimating the time delay expansion according to the multipath time delay of the time domain signal;

selecting a corresponding propagation mode according to the estimated time delay expansion to obtain a time domain signal in the propagation mode;

determining the parameter of the predetermined range according to the effective power of the time domain signal in the propagation mode.

Supplementary note 12, the method according to supplementary note 11, wherein said determining the parameter of the predetermined range from the power of the time domain signal in the propagation mode comprises;

taking a position satisfying the following condition as a starting position of the predetermined range: the effective power of the time domain signal at the position is greater than or equal to a preset second threshold, the effective power at the position next to the position is smaller than the second threshold, and the effective powers of the time domain signal at the position and the position next to the position both have a descending trend of change, wherein the second threshold is smaller than the first threshold;

and determining the length of the preset range according to the starting position.

Supplementary note 13, the method of supplementary note 11, wherein said determining the parameter of the predetermined range from the time domain signal in the propagation mode comprises:

determining the starting position of the predetermined range according to the estimated delay spread and the duration of one orthogonal frequency division multiplexing symbol;

and taking the distance between the starting position and the origin as the length of the preset range.

Supplementary note 14, the method according to supplementary note 9, wherein the noise suppression processing is performed by the following formula (1):

$g_{\mathrm{NS}}\left(l\right)=\left\{\begin{array}{c}{g}_{\mathrm{IP}}\left(l\right),\mathrm{if}(A_{\mathrm{IP}}\left(l\right)>T_{\mathrm{noc}})\mathrm{OR}\left[(0\≤l\≤N_{\mathrm{start}})\mathrm{AND}(N_{\mathrm{fft}}-(L_w-N_{\mathrm{start}})\≤l\≤N_{\mathrm{fft}})\right]\\ 0,\mathrm{otherwise}\end{array}\right.---\left(1\right)$

wherein, g_NS(l) Representing the time-domain signal at the location l after the noise suppression process, g_IP(l) Representing the time-domain signal at location l without noise suppression, A_IP(l) Representing the power, T, of the time-domain signal at position l_nocDenotes a first threshold value, N_startIndicating a starting position of a predetermined range, L_wIndicating the length of a predetermined range, N_fftNumber of points representing Fourier transform, l is more than or equal to 0 and less than or equal to N_fft-1。

Supplementary note 15, the method according to supplementary note 9, wherein the method further comprises:

and carrying out interpolation processing on the result of the channel preliminary estimation, and carrying out the inverse Fourier transform according to the result of the interpolation processing.

Claims (10)

1. A channel estimation apparatus, the apparatus comprising:

a first estimation unit, configured to perform preliminary estimation on a channel;

the first transformation unit is used for carrying out inverse Fourier transformation on the result of the channel preliminary estimation to obtain a time domain signal;

the noise suppression device comprises a noise suppression unit, a processing unit and a processing unit, wherein the noise suppression unit is used for performing noise suppression processing on time domain signals outside a predetermined range, and the time domain signals inside the predetermined range comprise time domain signals with effective power larger than a preset first threshold and time domain signals with effective power smaller than or equal to the first threshold due to the influence of noise;

and the second transformation unit is used for carrying out Fourier transformation on the time domain signal subjected to the noise suppression processing to obtain channel frequency domain response.

2. The apparatus of claim 1, wherein the apparatus further comprises:

a range determining unit, configured to select a propagation mode according to the time delay of the time domain signal obtained through the inverse fourier transform, and determine a parameter of the predetermined range, where the parameter of the predetermined range includes a start position of the predetermined range and a length of the predetermined range.

3. The apparatus of claim 2, wherein the range determination unit comprises:

the second estimation unit is used for estimating time delay expansion according to the multipath time delay of the time domain signal;

the mode selection unit is used for selecting a corresponding propagation mode according to the estimated time delay expansion to obtain a time domain signal in the propagation mode;

a parameter determination unit for determining a parameter of the predetermined range from an effective power of the time domain signal in the propagation mode.

4. The apparatus of claim 3, wherein the parameter determination unit comprises;

a first determination unit configured to take a position satisfying a condition as a start position of the predetermined range: the effective power of the time domain signal at the position is greater than or equal to a preset second threshold, the effective power at the position next to the position is smaller than the second threshold, and the effective powers of the time domain signal at the position and the position next to the position both have a descending trend of change, wherein the second threshold is smaller than the first threshold;

a second determining unit for determining the length of the predetermined range according to the start position.

5. The apparatus of claim 3, wherein the parameter determination unit comprises:

a third determining unit, configured to determine a starting position of the predetermined range according to the estimated delay spread and a duration of an ofdm symbol;

a fourth determination unit for taking a distance of the start position from an origin as a length of the predetermined range.

6. The apparatus according to claim 1, wherein the noise suppressing unit performs noise suppression processing using the following formula (1):

$g_{\mathrm{NS}}\left(l\right)=\left\{\begin{array}{c}{g}_{\mathrm{IP}}\left(l\right),\mathrm{if}(A_{\mathrm{IP}}\left(l\right)>T_{\mathrm{noc}})\mathrm{OR}\left[(0\≤l\≤N_{\mathrm{start}})\mathrm{AND}(N_{\mathrm{fft}}-(L_w-N_{\mathrm{start}})\≤l\≤N_{\mathrm{fft}})\right]\\ 0,\mathrm{otherwise}\end{array}\right.---\left(1\right)$

wherein, g_NS(l) Representing the time-domain signal at the location l after the noise suppression process, g_IP(l) Representing the time-domain signal at location l without noise suppression, A_IP(l) Representing the power, T, of the time-domain signal at position l_nocDenotes a first threshold value, N_startIndicating a starting position of a predetermined range, L_wIndicating the length of a predetermined range, N_fftNumber of points representing Fourier transform, l is more than or equal to 0 and less than or equal to N_fft-1。

7. The apparatus of claim 1, wherein the apparatus further comprises:

an interpolation unit for performing interpolation processing on a result of the channel preliminary estimation, and supplying a result of the interpolation processing to the first transformation unit for the inverse fourier transformation.

8. A receiver comprising the channel estimation device of claim 1.

9. A method of channel estimation, the method comprising:

performing preliminary estimation on a channel;

carrying out inverse Fourier transform on the result of the channel preliminary estimation to obtain a time domain signal;

carrying out noise suppression processing on time domain signals outside a predetermined range, wherein the time domain signals inside the predetermined range comprise time domain signals with effective power larger than a preset first threshold value and time domain signals with effective power smaller than or equal to the first threshold value due to the influence of noise;

and carrying out Fourier transform on the time domain signal subjected to the noise suppression processing to obtain channel frequency domain response.

10. The method of claim 9, wherein the method further comprises:

and selecting a propagation mode according to the time delay of the time domain signal obtained through inverse Fourier transform, and determining the parameter of the predetermined range, wherein the parameter of the predetermined range comprises the starting position of the predetermined range and the length of the predetermined range.