CN103391266A - Frequency domain channel response obtaining method and device - Google Patents

Abstract

The invention discloses a frequency domain channel response obtaining method and device. The method includes calculating a first noise amplitude threshold value g by using time domain channel response; calculating a second noise amplitude threshold value G by using the time domain channel response and the first noise amplitude threshold value g; calculating a third noise amplitude threshold value G' by using the second noise amplitude threshold value G; obtaining noise-restrained frequency domain channel response by using the third noise amplitude threshold value G'. By means of the method and device, channel estimation performance can be improved, and especially channel estimation performance under small bandwidth can be improved effectively.

Description

Method and device for acquiring frequency domain channel response

Technical Field

The present invention relates to the field of communications technologies, and in particular, to a method and a device for acquiring a frequency domain channel response.

Background

Channel estimation refers to a process of acquiring spatial channel information by using known pilot signal transmission, time-frequency position of pilot transmission, and data signal received at corresponding time-frequency position, that is, acquiring frequency domain channel response. As shown in fig. 1, a schematic diagram of a channel estimation process is shown, taking LTE (Long Term Evolution) downlink system as an example, and knowing that a downlink pilot transmission sequence is S, a received signal is Y, a spatial frequency domain channel is H + n, H represents an impulse response of a wireless fading channel, n represents white gaussian noise, and Y is (H + n) · S, so that a frequency domain channel response can be estimated

In order to further improve the precision of channel estimation and estimate the noise power value at the same time, a time domain windowing method can also be adopted; the specific process comprises the following steps: firstly, changing a frequency domain channel into a time domain, then determining the position of a maximum delay path of a useful signal according to the length of a Cyclic Prefix (CP) or prior information, then taking out a time domain noise path without the power of the useful signal, calculating the noise power value, and finally removing and converting the noise path back to the frequency domain to obtain a channel estimation value after noise suppression.

The method for setting the noise window according to the CP length comprises the following steps: taking the CP length as the time delay length of the maximum time delay path in the system, and calculating the position of a noise window; wherein, in the LTE system, the number N of Ts (sampling points) of CP under different bandwidths is specified_CPFFT (Fast Fourier transform) point number N_FFTNumber of subcarriers N_SCThen, the time domain position of the maximum delay path can be expressed as:

if IDFT (Inverse Discrete Fourier Transform) is adopted to Transform the Frequency domain to the time domain, the path number of the time domain channel response is the number N of Frequency domain pilot Frequency points on the same OFDM (Orthogonal Frequency Division Multiplexing) symbol_pliotThe number of remaining diameters is N_pliot-N_τIn consideration of the problem that signal power leakage causes the tail portion to contain useful signal power, the practical use can be madeLess noise path, e.g. taking the original noise window N_τ+1，N_τ+2，…，N_pliot-0.5N_τ}; if the mirror image IDFT is adopted to transform the frequency domain to the time domain, the path number of the mirror image time domain channel response is

The position of the useful signal path can be symmetrically existed

In the range of (1), the original noise window can be taken as

{2N_τ+1，2N_τ+2，…，N_pliot，N_pliot，+2，N_pliot+3，…，2N_pliot+1-2N_τ}

In the process of implementing the invention, the inventor finds that at least the following problems exist in the prior art:

in the LTE system, multiple bandwidth configuration schemes are supported, where the minimum bandwidth is configured to be 1.4MHz, and only 6 PRBs (physical Resource blocks) are occupied, and since the number of pilots on each PRB is consistent, the number of pilots is relatively small for a small bandwidth, and the amount of information available when performing channel estimation is small, which may cause an error in a noise estimation measurement result and a degradation in channel estimation performance.

In particular, when the original noise window is calculated in the conventional manner, the window length is small at a small bandwidth, for example, at a bandwidth of 1.4M, which is a valueIf the IDFT is adopted to transform the frequency domain to the time domain, the path number of the time domain channel response is 12, the residual path number is 6, the actually usable window length is less in consideration of the problem of power leakage of a tail useful signal, if the image IDFT is adopted to transform the frequency domain to the time domain, the path number of the image time domain channel response is 24, and the positions of the useful signal paths symmetrically exist in the time domain

The remaining noise path is approximately 1, and the number of paths is too small, resulting in inaccurate noise estimation. In addition, in a large time delay scene, the power of a useful signal path leaks to the edge of a noise window, and when the number of the inner diameters of the window is small, the estimated value of the noise power is greatly influenced, so that the noise suppression effect of signal estimation is influenced.

Disclosure of Invention

The embodiment of the invention provides a method and equipment for acquiring frequency domain channel response, which are used for improving the performance of channel estimation. In order to achieve the above purpose, the embodiments of the present invention provide the following technical solutions:

the embodiment of the invention provides a method for acquiring frequency domain channel response, which comprises the following steps:

calculating a first noise amplitude threshold value g by using time domain channel response;

calculating a second noise amplitude threshold value G by using the time domain channel response and the first noise amplitude threshold value G;

calculating a third noise amplitude threshold value G' by using the second noise amplitude threshold value G;

and obtaining the frequency domain channel response after noise suppression by using the third noise amplitude threshold value G'.

The embodiment of the invention provides a device for acquiring frequency domain channel response, which comprises:

the first calculation module is used for calculating a first noise amplitude threshold value g by utilizing time domain channel response;

a second calculating module, configured to calculate a second noise amplitude threshold value G by using the time domain channel response and the first noise amplitude threshold value G;

the third calculating module is used for calculating a third noise amplitude threshold value G' by using the second noise amplitude threshold value G;

and the obtaining module is used for obtaining the frequency domain channel response after noise suppression by using the third noise amplitude threshold value G'.

Compared with the prior art, the embodiment of the invention at least has the following advantages: the embodiment of the invention can improve the performance of channel estimation, and particularly can effectively improve the performance of channel estimation under small bandwidth.

Drawings

In order to more clearly illustrate the technical solution of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on the drawings without creative efforts.

Fig. 1 is a schematic diagram of a channel estimation process in the prior art;

fig. 2 is a schematic flowchart of a method for acquiring a frequency domain channel response according to an embodiment of the present invention;

fig. 3 is a schematic structural diagram of an apparatus for acquiring a frequency domain channel response according to a second embodiment of the present invention.

Detailed Description

The technical solutions in the present invention will be described clearly and completely with reference to the accompanying drawings, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example one

The embodiment of the invention provides a method for acquiring frequency domain channel response, which can be applied to systems such as LTE (Long term evolution) and LTE-A (LTE-Advanced ) and the like; the method can be applied to the noise estimation and channel estimation (i.e. obtaining the frequency domain channel response) process of a small bandwidth (i.e. the bandwidth is smaller than the preset bandwidth value), and the small bandwidth in the embodiment of the invention mainly refers to: bandwidth configuration in which the number of time domain paths within the noise window is less than a threshold, the threshold being determinable by simulation; the method can be simultaneously applied to the uplink and downlink channel estimation processes; as shown in fig. 2, the method for acquiring the frequency domain channel response includes the following steps:

step 201, obtaining the time domain channel response of each pilot symbol of each port of each receiving antenna.

In the embodiment of the present invention, obtaining the time domain channel response of each pilot symbol at each port of each receiving antenna specifically includes: obtaining the frequency domain channel estimation value of the pilot frequency position on each pilot frequency symbol of each port of each receiving antenna according to the following formula:

the frequency domain channel estimation value of the pilot frequency position on each pilot frequency symbol of each port of each receiving antenna is converted to the time domain by adopting an IDFT mode or a mirror IDFT mode to obtain the time domain channel response of each pilot frequency symbol of each port of each receiving antenna

Where r denotes a receive antenna, p denotes a port, l denotes a pilot symbol,

a frequency domain channel estimate representing the position of the pilot on the ith pilot symbol of the p-th port on the r-th receive antenna,are known guidesThe sequence of frequencies is such that,

a received signal extracted at the pilot position of each port for each receiving antenna, and

representing the time domain channel response of the ith pilot symbol of the p-th port on the r-th receive antenna.

Furthermore, in the process of transforming the frequency domain channel estimation value of the pilot frequency position on each pilot frequency symbol of each port of each receiving antenna to the time domain by adopting an IDFT mode, the time domain channel response of each pilot frequency symbol of each port of each receiving antenna is obtained

By the following formula:

in the process of transforming the frequency domain channel estimation value of the pilot frequency position on each pilot frequency symbol of each port of each receiving antenna to the time domain by adopting a mirror IDFT mode, the time domain channel response of each pilot frequency symbol of each port of each receiving antenna is obtained

By the following formula:

$h_l^{r,p}=\mathrm{IDFT}\left(H^{\′}\right),H^{\′}=\left\{\begin{array}{cc}{H}_l^{r,p}\left(i\right),& i=1,...,N_{\mathrm{pilot}}\\ H_l^{r,p}(2N_{\mathrm{pilot}}+1-i),& i=N_{\mathrm{pilot}}+1,...,2N_{\mathrm{pilot}}\end{array}\right.;$

wherein, the above-mentioned N_pliotThe number of paths for time domain channel response is the number of frequency domain pilot points on the same OFDM symbol.

It should be noted that, for each pilot symbol of each port of each receiving antenna, the subsequent correlation steps need to be performed separately.

Step 202, a first noise amplitude threshold value g is calculated by using the time domain channel response.

In the embodiment of the present invention, the process of calculating the first noise amplitude threshold value g by using the time domain channel response specifically includes, but is not limited to, the following ways:

in the first mode, the first noise amplitude threshold value g is calculated by using the following formula: g = ρ · a; where ρ is a weighting coefficient, which can be determined by simulation, a is the average of the amplitudes of all signal paths, and

mean represents the time domain channel response to the absolute value

And (6) taking an average value.

And secondly, calculating a first noise amplitude threshold value g by using the following formula (in this case, g is the average value of the amplitudes of the signal paths in the improved noise window):

j ═ { j | j ∈ win }; wherein mean represents the time domain channel response after taking the absolute value

And (6) taking an average value.

It should be noted that the modified noise window is different from the original noise window in that the modified noise window may include a part of the useful signal path, that is, the starting position of the noise window does not need to be based on the maximum delay path, but needs to include as many noise paths as possible.

In addition, the window taking method of the IDFT method and the mirror IDFT method are different, and when the window is taken by the IDFT method, win = may be used{2N₁+1,2N₁+2,...,N_pliot-N₁Taking the window by adopting a mirror image IDFT mode, and taking the window according to win = { N = when taking the window by adopting a mirror image IDFT mode₂+1,N₂+2,...,N_pliot,N_pliot+2,N_pliot+3,...,2N_pliot+1-N₂The method of (1) taking a window; wherein N is₁＜0.5N_τ，N₂＜2N_τThe value can be determined by simulation, and N_τThe time domain position of the maximum path of time delay, N_pliotThe number of paths for time domain channel response is the number of frequency domain pilot points on the same OFDM symbol.

Step 203, a second noise amplitude threshold value G is calculated by using the time domain channel response and the first noise amplitude threshold value G.

In the embodiment of the present invention, calculating the second noise amplitude threshold value G by using the time domain channel response and the first noise amplitude threshold value G includes: and calculating a noise amplitude average value by using the time domain channel response and the first noise amplitude threshold value G, and calculating a second noise amplitude threshold value G by using the noise amplitude average value.

Calculating a noise amplitude average value by using the time domain channel response and a first noise amplitude threshold value g, wherein the method comprises the following steps: comparing all signal path amplitudes used for calculating a first noise amplitude threshold value g with the first noise amplitude threshold value g, and taking out signal paths with amplitude values lower than the first noise amplitude threshold value g, so as to calculate a noise amplitude average value; specifically, the noise amplitude average value can be calculated using the following formula

$A_l^{r,p}=\mathrm{mean}\left(\right|h_l^{r,p}\left(k\right)\left|\right),$ And is $k=\left\{k\right|\left|h_l^{r,p}\left(k\right)\right|<g\};$ $k=\left\{k\right|\left|h_l^{r,p}\left(k\right)\right|<g\}$ Representing the time domain channel response after the absolute value of each pilot symbol of each port of each receiving antenna is taken

All the signal path amplitudes are compared with a first noise amplitude threshold value g, the signal path amplitude value which is taken out is lower than the signal path of the first noise amplitude threshold value g, mean represents the time domain channel response after the absolute value is taken out

And (6) taking an average value.

Calculating a second noise amplitude threshold value G using the noise amplitude average value, comprising: the second noise amplitude threshold value G is calculated using the following formula:

representing the amplitude of the noise on the pilot symbols at the ports of the receiving antennasMean value of

And averaging and then multiplying by 2 to obtain a second noise amplitude threshold value G.

In the embodiment of the invention, based on the obtained two-noise amplitude threshold value G, noise estimation can be carried out to accurately estimate the noise power under a small bandwidth, so that the noise estimated by the pilot frequency point channel is filtered according to the noise power value, and the detection performance is improved.

In the embodiment of the invention, the movable part can be taken out

Taking all signal paths with amplitude values lower than a second noise amplitude threshold value G as noise paths, and calculating the average power value of the noise paths as a noise power estimation value; specifically, the noise power estimation value can be calculated using the following formula

And is $m=\left\{m\right|\left|h_l^{r,p}\left(m\right)\right|<G\};$ $m=\left\{m\right|\left|h_l^{r,p}\left(m\right)\right|<G\}$ Means for taking out pilot symbols from ports of receiving antennasFor the time domain channel response after the value

All signal paths with amplitude values lower than a second noise amplitude threshold value G are taken as noise paths, mean represents time domain channel response after absolute value is taken

The square of (d) is averaged.

It should be noted that when using mirrored IDFT, the signal path is not a limitation

Is constant 0, so if a mirrored IDFT is used, the signal path also needs to be routed

And (5) removing.

In step 204, a third noise amplitude threshold value G' is calculated using the second noise amplitude threshold value G.

In the embodiment of the present invention, calculating a third noise amplitude threshold value G' by using the second noise amplitude threshold value G includes: the third noise amplitude threshold value G' is calculated according to the following formula: g' ═ min (λ)₁·h_max，λ₂G); wherein min represents λ₁Multiplied by h_maxAnd λ₂Multiplied by a small value, λ, of a second noise amplitude threshold value G₁And λ₂To preset values, h can be determined by simulation_maxIs composed of

The maximum value of the amplitude in each diameter.

And step 205, obtaining the frequency domain channel response after noise suppression by using a third noise amplitude threshold value G'. In the embodiment of the present invention, obtaining a frequency domain channel response after noise suppression by using a third noise amplitude threshold value G' includes: determiningAll amplitude values in the original noise window are higher than a third noise amplitude threshold value G', and the signal path which is not in the original noise window is an initial useful signal path; determining an initial useful signal path and signal paths in delta ranges at two sides of the initial useful signal path as useful signal paths, wherein delta is a preset value and can be determined through simulation; setting the other paths except the useful signal path in all the signal paths to zero to obtain the time domain signal response after noise suppression

Converting the time domain signal response after noise suppression to the frequency domain to obtain the frequency domain channel response after noise suppression

Further, in the process of obtaining the frequency domain channel response by using the IDFT, the following formula can be used to implement:in the process of obtaining the frequency domain channel response by adopting the mirror image IDFT, the method can be realized by the following formula: $H^{\&prime;}=\mathrm{DFT}\left({\tilde{h}}_l^{r,p}\right),$ $H_l^{r,p}\left(i\right)=0.5H^{\&prime;}\left(i\right)+0.5H^{\&prime;}({2N}_{\mathrm{pilot}}+1-i).$

in summary, in the embodiments of the present invention, the noise power under a small bandwidth can be estimated more accurately, and the detection performance is improved; and the channel estimation performance under a small bandwidth can be effectively improved, and the performance is obviously improved especially under a large time delay scene.

Example two

Based on the same inventive concept as the above method, an embodiment of the present invention further provides a device for acquiring a frequency domain channel response, as shown in fig. 3, where the device includes:

a first calculating module 11, configured to calculate a first noise amplitude threshold value g by using a time domain channel response;

a second calculating module 12, configured to calculate a second noise amplitude threshold value G by using the time domain channel response and the first noise amplitude threshold value G;

a third calculating module 13, configured to calculate a third noise amplitude threshold value G' by using the second noise amplitude threshold value G;

an obtaining module 14, configured to obtain a frequency domain channel response after noise suppression by using the third noise amplitude threshold value G'.

The obtaining module 14 is further configured to obtain a frequency domain channel estimation value of a pilot position on each pilot symbol of each port of each receiving antenna according to the following formula:

wherein,

a frequency domain channel estimate representing the position of the pilot on the ith pilot symbol of the p-th port on the r-th receive antenna,

for the known pilot sequence to be the one that is known,

a received signal extracted at a pilot position of each port for each receiving antenna;

transforming the frequency domain channel estimation value of the pilot frequency position on each pilot frequency symbol of each port of each receiving antenna to the time domain by adopting an Inverse Discrete Fourier Transform (IDFT) mode or a mirror IDFT mode to obtain the time domain channel response of each pilot frequency symbol of each port of each receiving antenna

The first calculating module 11 is specifically configured to calculate a first noise amplitude threshold value g by using the following formula: g = ρ · a; where p is a weighting coefficient, represents the time domain channel response of the ith pilot symbol of the pth port on the ith receiving antenna, and mean represents the time domain channel response after the absolute value is takenTaking an average value; or,

the first noise amplitude threshold value g is calculated using the following equation:j ═ { j | j ∈ win }; wherein,

represents the time domain channel response of the ith pilot symbol of the pth port on the ith receiving antenna, and mean represents the time domain channel response after the absolute value is takenTaking an average value; when the window is taken by IDFT method, win is {2N ═₁+1,2N₁+2,...,N_pliot-N₁When the window is taken by adopting a mirror image IDFT mode, win is equal to { N }₂+1,N₂+2,...,N_pliot,N_pliot+2,N_pliot+3,...,2N_pliot+1-N₂}; and N is₁＜0.5N_τ，N₂＜2N_τAnd N is_τThe time domain position of the maximum path of time delay, N_pliotThe number of paths for time domain channel response is the number of frequency domain pilot points on the same OFDM symbol.

The second calculating module 12 is specifically configured to calculate a noise amplitude average value by using the time domain channel response and the first noise amplitude threshold value G, and calculate the second noise amplitude threshold value G by using the noise amplitude average value.

The second calculating module 12 is further configured to calculate the noise amplitude average value by using the following formula

And is

Wherein,

representing the time domain channel response of the ith pilot symbol of the p-th port on the r-th receive antenna,

representing the time domain channel response after the absolute value of each pilot symbol of each port of each receiving antenna is taken

All the signal path amplitudes are compared with a first noise amplitude threshold value g, the signal path amplitude value which is taken out is lower than the signal path of the first noise amplitude threshold value g, mean represents the time domain channel response after the absolute value is taken out

And (6) taking an average value.

The second calculating module 12 is further configured to calculate the second noise amplitude threshold value G by using the following formula:

which represents averaging the noise amplitude over the pilot symbols at the ports of the receiving antennas

And after averaging, multiplying by 2 to obtain the second noise amplitude threshold value G.

The apparatus further comprises: a fourth calculation module 15 for calculating the noise power estimation value using the following formula

${\left({\mathrm{\&sigma;}}_l^{r,p}\right)}^2=\mathrm{mean}\left({\left|h_l^{r,p}\left(m\right)\right|}^2\right),$ And is $m=\left\{m\right|\left|h_l^{r,p}\left(m\right)\right|<G\};$ Wherein,

representing the time domain channel response of the ith pilot symbol of the p-th port on the r-th receive antenna,

representing the time domain channel response after the absolute value of each pilot symbol of each port of each receiving antenna is taken

All signal paths with amplitude values lower than a second noise amplitude threshold value G are taken as noise paths, mean represents time domain channel response after absolute value is taken

The square of (d) is averaged.

The third calculating module 13 is specifically configured to calculate a third noise amplitude threshold value G' according to the following formula:wherein min represents λ₁Multiplied by h_maxAnd λ₂Multiplied by a small value of the second noise amplitude threshold value G,γ₁and λ₂Is a preset value, h_maxIs composed of

The maximum value of the amplitude in each of the paths,

representing the time domain channel response of the ith pilot symbol of the p-th port on the r-th receive antenna.

The obtaining module 14 is specifically configured to determineWherein all amplitude values are higher than a third noise amplitude threshold value G', and the signal path not in the original noise window is the initial useful signal path

Representing the time domain channel response of the ith pilot symbol of the pth port on the mth receiving antenna; determining the initial useful signal path and signal paths in the range of delta at two sides of the initial useful signal path as useful signal paths, wherein delta is a preset value; setting other paths except the useful signal path in all the signal paths to zero to obtain a time domain signal response after noise suppression; and converting the time domain signal response after the noise suppression into a frequency domain to obtain the frequency domain channel response after the noise suppression.

The modules of the device can be integrated into a whole or can be separately deployed. The modules can be combined into one module, and can also be further split into a plurality of sub-modules.

Through the above description of the embodiments, those skilled in the art will clearly understand that the present invention may be implemented by software plus a necessary general hardware platform, and certainly may also be implemented by hardware, but in many cases, the former is a better embodiment. Based on such understanding, the technical solutions of the present invention may be embodied in the form of a software product, which is stored in a storage medium and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute the methods according to the embodiments of the present invention.

Those skilled in the art will appreciate that the drawings are merely schematic representations of one preferred embodiment and that the blocks or flow diagrams in the drawings are not necessarily required to practice the present invention.

Those skilled in the art will appreciate that the modules in the devices in the embodiments may be distributed in the devices in the embodiments according to the description of the embodiments, and may be correspondingly changed in one or more devices different from the embodiments. The modules of the above embodiments may be combined into one module, or further split into multiple sub-modules.

The above-mentioned serial numbers of the embodiments of the present invention are merely for description and do not represent the merits of the embodiments.

The above disclosure is only for a few specific embodiments of the present invention, but the present invention is not limited thereto, and any variations that can be made by those skilled in the art are intended to fall within the scope of the present invention.

Claims (18)

1. A method for obtaining a frequency domain channel response, comprising:

calculating a first noise amplitude threshold value g by using time domain channel response;

calculating a second noise amplitude threshold value G by using the time domain channel response and the first noise amplitude threshold value G;

calculating a third noise amplitude threshold value G' by using the second noise amplitude threshold value G;

and obtaining the frequency domain channel response after noise suppression by using the third noise amplitude threshold value G'.

2. The method of claim 1, wherein the calculating the first noise amplitude threshold value g using the time domain channel response further comprises:

obtaining the frequency domain channel estimation value of the pilot frequency position on each pilot frequency symbol of each port of each receiving antenna according to the following formula:

wherein,

a frequency domain channel estimate representing the position of the pilot on the ith pilot symbol of the p-th port on the r-th receive antenna,

for the known pilot sequence to be the one that is known,a received signal extracted at a pilot position of each port for each receiving antenna;

transforming the frequency domain channel estimation value of the pilot frequency position on each pilot frequency symbol of each port of each receiving antenna to the time domain by adopting an Inverse Discrete Fourier Transform (IDFT) mode or a mirror IDFT mode to obtain the time domain channel response of each pilot frequency symbol of each port of each receiving antenna

3. The method of claim 1, wherein said calculating a first noise amplitude threshold value g using the time domain channel response comprises:

the first noise amplitude threshold value g is calculated using the following equation: g = ρ · a; where p is a weighting coefficient,

represents the time domain channel response of the ith pilot symbol of the pth port on the ith receiving antenna, and mean represents the time domain channel response after the absolute value is taken

Taking an average value; or,

the first noise amplitude threshold value g is calculated using the following equation:

j ═ { j | j ∈ win }; wherein,represents the time domain channel response of the ith pilot symbol of the pth port on the ith receiving antenna, and mean represents the time domain channel response after the absolute value is taken

Taking an average value; when the window is taken by IDFT method, win is {2N ═₁+1,2N₁+2,...,N_pliot-N₁When a mirror IDFT mode is adopted to take a window, win = { N = }₂+1,N₂+2,...,N_plion,N_pliot+2,N_pliot+3,...,2N_pliot+1-N₂}; and N is₁＜0.5N_τ，N₂＜2N_τAnd N is_τThe time domain position of the maximum path of time delay, N_pliotThe number of paths for time domain channel response is the number of frequency domain pilot points on the same OFDM symbol.

4. The method of claim 1, wherein calculating a second noise amplitude threshold G using the time domain channel response and the first noise amplitude threshold G comprises:

and calculating a noise amplitude average value by using the time domain channel response and the first noise amplitude threshold value G, and calculating the second noise amplitude threshold value G by using the noise amplitude average value.

5. The method of claim 4, wherein calculating a noise amplitude average using the time domain channel response and the first noise amplitude threshold value g comprises:

calculating the noise amplitude average value using the following formula

And is

Wherein,

representing the time domain channel response of the ith pilot symbol of the p-th port on the r-th receive antenna,

representing the time domain channel response after the absolute value of each pilot symbol of each port of each receiving antenna is taken

All the signal path amplitudes are compared with a first noise amplitude threshold value g, the signal path amplitude value which is taken out is lower than the signal path of the first noise amplitude threshold value g, mean represents the time domain channel response after the absolute value is taken out

And (6) taking an average value.

6. The method of claim 4, wherein calculating the second noise amplitude threshold value G using the noise amplitude average value comprises:

calculating the second noise amplitude threshold value G using the following equation:

which represents averaging the noise amplitude over the pilot symbols at the ports of the receiving antennas

And after averaging, multiplying by 2 to obtain the second noise amplitude threshold value G.

7. The method of claim 1, wherein a second noise amplitude threshold G is calculated using the time domain channel response and the first noise amplitude threshold G, and thereafter further comprising:

the noise power estimate is calculated using the following formula

And is

Wherein,represents the time domain channel response of the ith pilot symbol of the p-th port on the r-th receive antenna,representing the time domain channel response after the absolute value of each pilot symbol of each port of each receiving antenna is taken

All amplitude values in are lower than the secondThe signal path of the noise amplitude threshold value G is taken as the noise path, mean represents the time domain channel response after the absolute value is taken

The square of (d) is averaged.

8. The method of claim 1, wherein calculating a third noise amplitude threshold value G' using the second noise amplitude threshold value G comprises:

the third noise amplitude threshold value G' is calculated according to the following formula: g' ═ min (λ)₁·h_max，λ₂G); wherein min represents λ₁Multiplied by h_maxAnd λ₂Multiplied by a small value, λ, of a second noise amplitude threshold value G₁And λ₂Is a preset value, h_maxIs composed of

The maximum value of the amplitude in each of the paths,

representing the time domain channel response of the ith pilot symbol of the p-th port on the r-th receive antenna.

9. The method of claim 1, wherein obtaining a noise-suppressed frequency domain channel response using the third noise magnitude threshold G' comprises:

determining

Wherein all amplitude values are higher than a third noise amplitude threshold value G', and the signal path not in the original noise window is the initial useful signal path

Time domain channel representing the ith pilot symbol of the p port on the r receive antennaResponding;

determining the initial useful signal path and signal paths in the range of delta at two sides of the initial useful signal path as useful signal paths, wherein delta is a preset value;

setting other paths except the useful signal path in all the signal paths to zero to obtain a time domain signal response after noise suppression;

and converting the time domain signal response after the noise suppression into a frequency domain to obtain the frequency domain channel response after the noise suppression.

10. An apparatus for obtaining a frequency domain channel response, comprising:

the first calculation module is used for calculating a first noise amplitude threshold value g by utilizing time domain channel response;

a second calculating module, configured to calculate a second noise amplitude threshold value G by using the time domain channel response and the first noise amplitude threshold value G;

the third calculating module is used for calculating a third noise amplitude threshold value G' by using the second noise amplitude threshold value G;

and the obtaining module is used for obtaining the frequency domain channel response after noise suppression by using the third noise amplitude threshold value G'.

11. The apparatus of claim 10,

the obtaining module is further configured to obtain a frequency domain channel estimation value of a pilot position on each pilot symbol of each port of each receiving antenna according to the following formula:

wherein,a frequency domain channel estimate representing the position of the pilot on the ith pilot symbol of the p-th port on the r-th receive antenna,

for the known pilot sequence to be the one that is known,

a received signal extracted at a pilot position of each port for each receiving antenna;

transforming the frequency domain channel estimation value of the pilot frequency position on each pilot frequency symbol of each port of each receiving antenna to the time domain by adopting an Inverse Discrete Fourier Transform (IDFT) mode or a mirror IDFT mode to obtain the time domain channel response of each pilot frequency symbol of each port of each receiving antenna

12. The apparatus of claim 10,

the first calculating module is specifically configured to calculate a first noise amplitude threshold value g by using the following formula: g = ρ · a; where p is a weighting coefficient,

represents the time domain channel response of the ith pilot symbol of the pth port on the ith receiving antenna, and mean represents the time domain channel response after the absolute value is taken

Taking an average value; or,

the first noise amplitude threshold value g is calculated using the following equation:

j ═ { j | j ∈ win }; wherein,

representing the time domain channel response of the ith pilot symbol of the p port on the r receiving antenna, mean representing the absolute value of the received signalTime domain channel response of

Taking an average value; when the window is taken by IDFT method, win is {2N ═₁+1,2N₁+2,...,N_pliot-N₁When a mirror IDFT mode is adopted to take a window, win = { N = }₂+1,N₂+2,...,N_pliot,N_pliot+2,N_pliot+3,...,2N_pliot+1-N₂}; and N is₁＜0.5N_τ，N₂＜2N_τAnd N is_τThe time domain position of the maximum path of time delay, N_pliotThe number of paths for time domain channel response is the number of frequency domain pilot points on the same OFDM symbol.

13. The apparatus of claim 10,

the second calculating module is specifically configured to calculate a noise amplitude average value by using the time domain channel response and the first noise amplitude threshold value G, and calculate the second noise amplitude threshold value G by using the noise amplitude average value.

14. The apparatus of claim 13,

the second calculating module is further used for calculating the noise amplitude average value by using the following formula

And is

Wherein,

the ith pilot symbol representing the p port on the r receive antennaThe time-domain channel response of the number,

representing the time domain channel response after the absolute value of each pilot symbol of each port of each receiving antenna is taken

All the signal path amplitudes are compared with a first noise amplitude threshold value g, the signal path amplitude value which is taken out is lower than the signal path of the first noise amplitude threshold value g, mean represents the time domain channel response after the absolute value is taken out

And (6) taking an average value.

15. The apparatus of claim 13,

the second calculating module is further configured to calculate the second noise amplitude threshold value G by using the following formula:which represents averaging the noise amplitude over the pilot symbols at the ports of the receiving antennas

And after averaging, multiplying by 2 to obtain the second noise amplitude threshold value G.

16. The apparatus of claim 10, further comprising:

a fourth calculating module for calculating the noise power estimation value by using the following formula

And is

Wherein,

representing the time domain channel response of the ith pilot symbol of the p-th port on the r-th receive antenna,

representing the time domain channel response after the absolute value of each pilot symbol of each port of each receiving antenna is taken

All signal paths with amplitude values lower than a second noise amplitude threshold value G are taken as noise paths, mean represents time domain channel response after absolute value is taken

The square of (d) is averaged.

17. The apparatus of claim 10,

the third calculating module is specifically configured to calculate a third noise amplitude threshold value G' according to the following formula:

wherein min represents λ₁Multiplied by h_maxAnd λ₂Multiplied by a small value, λ, of a second noise amplitude threshold value G₁And λ₂Is a preset value, h_maxIs composed of

The maximum value of the amplitude in each of the paths,

indicating the p port on the r receiving antennaTime domain channel response of l pilot symbols.

18. The apparatus of claim 10,

the obtaining module is particularly used for determining

Wherein all amplitude values are higher than a third noise amplitude threshold value G', and the signal path not in the original noise window is the initial useful signal pathRepresenting the time domain channel response of the ith pilot symbol of the pth port on the mth receiving antenna;

determining the initial useful signal path and signal paths in the range of delta at two sides of the initial useful signal path as useful signal paths, wherein delta is a preset value;

setting other paths except the useful signal path in all the signal paths to zero to obtain a time domain signal response after noise suppression;

and converting the time domain signal response after the noise suppression into a frequency domain to obtain the frequency domain channel response after the noise suppression.

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