CN103379054B - Channel estimation methods and device - Google Patents
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Abstract
The invention discloses a kind of channel estimation methods, including：Calculate time domain impulse response estimation；With utilize time domain impulse response estimation to calculate the domain channel response estimation of all subcarriers.Wherein, when calculating time domain impulse response estimation, estimate composition of vector using the domain channel response for the pilot sub-carrier selected, and use the submatrix generation coefficient matrix with the pilot sub-carrier selected with corresponding relation, again by the coefficient matrix and the multiplication of vectors, time domain impulse response estimation is obtained.The invention also discloses a kind of channel estimating apparatus.Using the present invention, not only realize simple, moreover it is possible to lift the performance of channel estimation.
Description
Technical field
The invention belongs to the communications field, more particularly to channel estimation methods and device.
Background technology
The essential characteristic of wireless channel is its communication environments complicated and changeable.Due to the reflector or scattered of spatial stochastically distribution
Beam so that wireless signal has different delays and attenuation version when reaching receiver, the multipath extension of this time-domain is now
As causing wireless signal Selective intensity, hereinafter referred to frequency selective fading occur in frequency domain.Due to transceiver or
The change of communication environments so that the frequency ambiguity when wireless signal of single-frequency reaches receiver, the disperse of this frequency domain show
As causing wireless signal Selective intensity, hereinafter referred to as time selective fading occur in time-domain.Wireless communication system design
Primary goal be exactly to resist these above-mentioned fade-outs.
In wireless local area network (WLAN) system, because emitter and receiver location are generally fixed, communication environments are also generally with pole
Slow rate changes, therefore time selective fading is not notable.But wireless local area network (WLAN) system is to obtain higher access bandwidth,
It is required for taking larger band resource (such as 20MHz), so, even if the space reflection body of propagation channel distribution or scattered
Beam is smaller, and significant frequency selective fading also occurs.
OFDM (OFDM, Orthogonal Frequency Division Multiplexing) technology is nothing
The basic technology of line LAN system.In order to accurately detect, demodulate the symbol of each subcarrier in ofdm system, frequency is overcome to select
The influence that the decline of selecting property is brought, receiver need accurately to estimate the frequency domain channel feature H on each subcarrierk, wherein k is son
Carrier index.
Wireless local area network (WLAN) system because its cheap cost requirement and power consumption requirements, channel estimation method generally from by
Least square (LS) channel estimation of frequency pilot sign.LS channel estimations are as follows：yk=Hk·pk+nk.Wherein, pkRepresent subcarrier k
On frequency pilot sign, nkIt is the white Gaussian noise on subcarrier k, ykIt is the reception symbol on subcarrier k.LS channel estimations can obtain
Arrive
LS channel estimations can only obtain the frequency domain channel feature of the subcarrier of frequency pilot sign.For no frequency pilot sign
Subcarrier, it can be obtained by two closest pilot sub-carrier interpolation of frequency domain.Wireless local area network (WLAN) system generally use is such as
Lower interpolation method：
Firstth, linear interpolation.
Consider wireless channel frequency domain feature and computation complexity, the simple linear interpolation of wireless local area network (WLAN) system generally use
Algorithm, but its poor-performing, under wireless lan channel environment, more than 2dB power attenuation can be brought.Fig. 1 shows LS
The channel estimating performance of channel estimation+linear interpolation, transmitted using 64QAM, 5/6 code check, 2 hairs 2 are received.Abscissa represents in Fig. 1
Signal to noise ratio (SNR, Signal to Noise Ratio), ordinate represent FER (FER, Frame Error Rate), solid line
Perfect channel estimation is represented, dotted line represents LS channel estimations, it can be seen that LS channel estimations are damaged compared to perfect channel estimation performance
Lose 2 to 3dB.
Secondth, Wiener interpolation.
From the point of view of least mean-square error, Wiener interpolation is optimal interpolation method.LS channel estimations+Wiener interpolation
LS channel estimations+linear interpolation should be better than.But Wiener interpolation needs to predict channel correlation properties, it is also desirable to matrix inversion operation,
Realize complex.
3rd, FFT interpolations.
The OFDM technology feature that combining wireless LAN system uses, FFT interpolations are also a kind of simple and easy raising letter
The method that quality is estimated in road.By the existing FFT of ofdm system and IFFT computing modules, if the sum of system sub-carriers is M,
The sum of pilot sub-carrier is N, and the domain channel response estimation that can first become N number of pilot sub-carrier of changing commanders with N points IFFT is transformed to N
Point time domain impulse response estimation, that is, being believed the frequency domain of all N number of pilot sub-carriers using the N point IFFT matrixes set
Road estimation is transformed to the response of N points time domain impulse, then the response estimation of N points time domain impulse is transformed into M point frequency domains with M point FFTs
Channel response is estimated, that is, the response estimation of N points time domain impulse is transformed into M point frequency domains using the M point FFT matrixes set
Channel response is estimated, so as to obtain the estimation of the domain channel response of all subcarriers.However, in the ofdm system of reality, examine
Consider the index request of adjacent channel leakage (ACLR), OFDM subcarrier in frequency domain both ends can reserve a number of virtual subcarrier not
Symbol is transmitted, as protective separation.Because real system can not know the channel estimation in frequency domain at virtual subcarrier, algorithm performance
It can be severely impacted.
The content of the invention
In view of this, it is an object of the present invention to provide realize simple and good performance channel estimation methods and device.
In order to which some aspects of the embodiment to disclosure have a basic understanding, simple summary shown below is.Should
Summarized section is not extensive overview, nor to determine key/critical component or describe the protection domain of these embodiments.
Its sole purpose is that some concepts are presented with simple form, in this, as the preamble of following detailed description.
The technical proposal of the invention is realized in this way：
A kind of channel estimation methods, this method include：
Calculate time domain impulse response estimation；With,
The domain channel response that all subcarriers of estimation calculating are responded using time domain impulse is estimated；
Wherein, the calculating time domain impulse response estimation includes：
Select the pilot sub-carrier to be used；
Estimate composition of vector using the domain channel response for the pilot sub-carrier selected；
Using selected from the default Fourier transformation FFT matrixes and pilot sub-carrier with selecting have pair
The submatrix generation coefficient matrix that should be related to；
By the coefficient matrix and the multiplication of vectors, time domain impulse response estimation is obtained.
In a kind of embodiment, this method also includes：The domain channel response of calculating section or whole pilot sub-carriers is estimated.
In a kind of embodiment, by the domain channel response estimation arranged in sequence composition institute for the L pilot sub-carrier selected
State vector；Wherein L≤K, K are the sum of pilot sub-carrier, and L is more than or equal to the length of time domain impulse response.
Optionally, as L ＜ K, everyIndividual pilot sub-carrier, select a pilot sub-carrier.
In a kind of embodiment, this method also includes：All K pilot sub-carriers are divided intoIndividual packet, wherein
Each packet includes L pilot sub-carrier, and L ＜ K, L are more than or equal to the length of time domain impulse response；
For some or all packets, the step of calculating time domain impulse response is estimated is performed respectively；
The domain channel response estimation that all subcarriers of estimation calculating are responded using time domain impulse, including：To obtaining
The response estimation of all time domain impulses be weighted average, final time domain impulse response estimation is obtained, using described final
Time domain impulse response estimation calculates the domain channel response estimation of all subcarriers.
Optionally, the domain channel response estimation arranged in sequence for the L pilot sub-carrier selected is formed into the vector.
Optionally, during the generation coefficient matrix：
Select line number index identical with the sub-carrier indices of the L pilot sub-carrier from the default FFT matrixes
L row elements；
Row number index and the location index identical of the time domain impulse to be calculated response estimation are selected from the L row elements
L column elements, or, row number index and the location index of the time domain impulse to be calculated response estimation are selected from the L row elements
There are the L column elements of constant offset relation；
Utilize the L selected2Individual element forms submatrix；
To sub- matrix inversion, coefficient matrix is obtained.
Optionally, when generating coefficient matrix：
Transposition is carried out to the default FFT matrixes；
The sub-carrier indices identical L of row number index and the L pilot sub-carrier is selected from the FFT matrixes after transposition
Column element；
Line number index and the location index identical of the time domain impulse to be calculated response estimation are selected from the L column elements
L row elements, or, line number index and the location index of the time domain impulse to be calculated response estimation are selected from the L column elements
There are the L column elements of constant offset relation；
Utilize the L selected2Individual element forms submatrix；
To sub- matrix inversion, coefficient matrix is obtained.
Optionally, during the generation coefficient matrix：
Select line number index identical with the sub-carrier indices of the L pilot sub-carrier from the default FFT matrixes
L row elements；
Row number index and the location index identical of the time domain impulse to be calculated response estimation are selected from the L row elements
M column elements, or, row number index and the location index of the time domain impulse to be calculated response estimation are selected from the L row elements
M column elements with constant offset relation, wherein M≤L；
Submatrix is formed using the L × M element selected；
To sub- Matrix Calculating pseudoinverse, coefficient matrix is obtained.
Optionally, during the generation coefficient matrix：
Transposition is carried out to the default FFT matrixes；
The sub-carrier indices identical L of row number index and the L pilot sub-carrier is selected from the FFT matrixes after transposition
Column element；
Line number index and the location index identical of the time domain impulse to be calculated response estimation are selected from the L column elements
M row elements, or, line number index and the location index of the time domain impulse to be calculated response estimation are selected from the L column elements
M row elements with constant offset relation, wherein M≤L；
Submatrix is formed using the L × M element selected；
To sub- Matrix Calculating pseudoinverse, coefficient matrix is obtained.
In a kind of embodiment, the default FFT matrixes are N × N matrix, and wherein N is the sum of subcarrier.
Optionally, using the default FFT matrixes, estimation is responded to time domain impulse and carries out FFT, calculates all sons
The domain channel response estimation of carrier wave.
A kind of channel estimating apparatus, the device include：
First module, for calculating time domain impulse response estimation；With,
Second unit, for calculating the domain channel response estimation of all subcarriers using time domain impulse response estimation；
Wherein described first module includes：
First module, for selecting the pilot sub-carrier to be used, utilize the frequency domain channel for the pilot sub-carrier selected
Response estimation composition of vector；
Second module, for utilizing selected from the default Fourier transformation FFT matrixes and pilot tone with selecting
Carrier wave has the submatrix generation coefficient matrix of corresponding relation；
3rd module, for by the coefficient matrix and the multiplication of vectors, obtaining time domain impulse response estimation.
In a kind of embodiment, the device also includes：Third unit, for calculating section or the frequency domain of whole pilot sub-carriers
Channel response is estimated.
In a kind of embodiment, first module by the estimation of the domain channel response of the L pilot sub-carrier selected by
Sequence is arranged in the vector；Wherein and L≤K, K are the sum of pilot sub-carrier, and L is more than or equal to the length of time domain impulse response
Degree.
Optionally, as L ＜ K, first module everyIndividual pilot sub-carrier, select pilot tone
Carrier wave.
In a kind of embodiment, the device also includes：Unit the 4th, for be divided into all K pilot sub-carriersIndividual packet, wherein each packet includes L pilot sub-carrier, and L ＜ K, L are more than or equal to time domain impulse response
Length；
The first module is directed to some or all packets, performs the operation for calculating time domain impulse response estimation respectively；
The second unit is first weighted averagely to obtained all time domain impulses response estimation, obtains final time domain
Shock response is estimated, recycles final time domain impulse to respond the domain channel response estimation that estimation calculates all subcarriers.
Optionally, first module, the domain channel response for the L pilot sub-carrier selected is estimated into arranged in sequence
Form the vector.
Optionally, second module includes：
First choice submodule, line number index and the L pilot sub-carrier are selected from the default FFT matrixes
Sub-carrier indices identical L row elements；
Second selection submodule, selects row number index to estimate with the time domain impulse to be calculated response from the L row elements
Location index identical L column elements, or select row number index to be responded with the time domain impulse to be calculated from the L row elements
The location index of estimation has the L column elements of constant offset relation；
Submodule is generated, utilizes the L selected2Individual element forms the submatrix, and the submatrix is inverted, and obtains
The coefficient matrix.
Optionally, second module includes：
First choice submodule, transposition, the alternative column from the FFT matrixes after transposition are carried out to the default FFT matrixes
Number index and the sub-carrier indices identical L column elements of the L pilot sub-carrier；
Second selection submodule, selects line number index to estimate with the time domain impulse to be calculated response from the L column elements
Location index identical L row elements, or select line number index to be responded with the time domain impulse to be calculated from the L column elements
The position of estimation has the L row elements of constant offset relation；
Generation module, utilize the L selected2Individual element forms the submatrix, and the submatrix is inverted, and obtains institute
State coefficient matrix.
Optionally, second module includes：
First choice submodule, the subcarrier rope of line number index and L pilot sub-carrier is selected from default FFT matrixes
Draw identical L row elements；
Second selection submodule, selects row number index to estimate with the time domain impulse to be calculated response from the L row elements
Location index identical M column elements, or, select row number index to be rung with the time domain impulse to be calculated from the L row elements
The location index that should be estimated has the M column elements of constant offset relation, wherein M≤L；
Submodule is generated, the submatrix is formed using the L × M element selected, and pseudoinverse is asked to the submatrix,
Obtain the coefficient matrix.
Optionally, second module includes：
First choice submodule, transposition is carried out to FFT matrixes, and row number index and institute are selected from the FFT matrixes after transposition
State the sub-carrier indices identical L column elements of L pilot sub-carrier；
Second selection submodule, selects line number index to estimate with the time domain impulse to be calculated response from the L column elements
Location index identical M row elements, or, select line number index to be rung with the time domain impulse to be calculated from the L column elements
The location index that should be estimated has the M row elements of constant offset relation, wherein M≤L；
Generation module, the submatrix is formed using the L × M element selected, and pseudoinverse is asked to the submatrix, obtained
To the coefficient matrix.
In a kind of embodiment, the default FFT matrixes are N × N matrix, and wherein N is the sum of subcarrier.
Optionally, the second unit uses the default FFT matrixes, and responding estimation to time domain impulse carries out FFT changes
Change, calculate the domain channel response estimation of all subcarriers.
For above-mentioned and related purpose, one or more embodiments include will be explained in below and in claim
In the feature that particularly points out.Following explanation and accompanying drawing describe some illustrative aspects in detail, and its instruction is only
Some modes in the utilizable various modes of principle of each embodiment.Other benefits and novel features will be under
The detailed description in face is considered in conjunction with the accompanying and becomes obvious, the disclosed embodiments be will include all these aspects and they
Be equal.
Figure of description
Fig. 1 is the channel estimating performance schematic diagram of LS channel estimations+linear interpolation；
Fig. 2 is the flow chart of channel estimation methods of the present invention；
Fig. 3 is the schematic diagram of the channel estimating performance of the embodiment of the present invention；
Fig. 4 is the structural representation of channel estimating apparatus of the present invention；
Fig. 5 is the structural representation of channel estimating apparatus in the embodiment of the present invention four；
Fig. 6 is the structural representation of channel estimating apparatus in the embodiment of the present invention five.
Embodiment
The following description and drawings fully show specific embodiments of the present invention, to enable those skilled in the art to
Put into practice them.Other embodiments can include structure, logic, it is electric, process and other change.Embodiment
Only represent possible change.Unless explicitly requested, otherwise single component and function are optional, and the order operated can be with
Change.The part of some embodiments and feature can be included in or replace part and the feature of other embodiments.This hair
The scope of bright embodiment includes the gamut of claims, and claims is all obtainable equivalent
Thing.Herein, these embodiments of the invention can individually or generally be represented that this is only with term " invention "
For convenience, and if in fact disclosing the invention more than one, the scope for being not meant to automatically limit the application is to appoint
What single invention or inventive concept.
Fig. 2 is the flow chart of channel estimation methods of the present invention, and the flow includes：
Step 21：Calculate time domain impulse response estimation.
Step 22：The domain channel response that all subcarriers of estimation calculating are responded using time domain impulse is estimated.
Wherein, above-mentioned steps 21 specifically include：
Step 211：Select the pilot sub-carrier to be used.
Step 212：Estimate composition of vector using the domain channel response for the pilot sub-carrier selected.
Step 213：Have using selected from the default FFT matrixes and pilot sub-carrier with selecting corresponding
The submatrix generation coefficient matrix of relation.
Step 214：By the coefficient matrix and the multiplication of vectors, time domain impulse response estimation is obtained.
In most cases, the length of time domain impulse response estimation is much smaller than the quantity of pilot sub-carrier, so existing
Channel estimation method in, it is fixed to use all pilot sub-carriers and dimension and pilot sub-carrier quantity identical matrix computations
Time domain impulse response estimation, equivalent to bulk redundancy information is introduced in calculating process, this not only causes calculating to become complicated,
The performance of channel estimation can also be reduced.
Channel estimation methods provided by the invention, when calculating time domain impulse response estimation, selective use pilot tone
The domain channel response estimation composition of vector of carrier wave, and use the sub- square with the pilot sub-carrier selected with corresponding relation
Battle array generation coefficient matrix, equivalent to the redundancy eliminated in used matrix, this aspect reduces the complexity of calculating,
On the other hand a part of noise can be filtered out in time-domain, improves the performance of channel estimation.
Default FFT matrixes have common implication in the present invention, for example, it is assumed that to column vector xNFFT computings are carried out, then
It can be carried out according to equation below：XN=FNxN.F thereinNIt is exactly N point FFT matrixes.
The embodiment of channel estimation methods of the present invention is given below.
【Embodiment one】
The application scenarios of the present embodiment one include：Total number of sub-carriers in system is N, including virtual, pilot tone and direct current are protected
Protect subcarrier；The sum of pilot sub-carrier is K, and sub-carrier indices corresponding to N number of subcarrier are respectively 0,1 ..., N-1；Default N
× N FFT matrixes.
Channel estimation methods in the present embodiment one comprise the following steps 1~step 5.
Step 1：Calculate the domain channel response estimation H of all pilot sub-carriersK。
As optional embodiment, method of estimation can be simple, low complex degree LS channel estimations or its
The more preferable method of estimation of his performance.
Step 2：L pilot sub-carrier is selected, the domain channel response estimation for the pilot sub-carrier selected sequentially is arranged
It is classified as column vector HL, wherein L≤K, and L is more than or equal to the length of time domain impulse response.The length of time domain impulse response is to connect
Receiving end is estimated that what is come.
As optional embodiment, as L ＜ K, everyIndividual pilot sub-carrier, select pilot tone
Carrier wave, the sub-carrier indices for the L pilot sub-carrier selected are l0, l1..., lL-1, lk∈[0 N-1]。
Step 3：L × L submatrix is selected from N × N FFT matrixes, coefficient matrix F is generated using the submatrix-1。
As the first optional embodiment, line number index and L selected first are selected from N × N FFT matrixes
The sub-carrier indices identical L row elements of pilot sub-carrier, that is, it is l to select line number index0, l1..., lL-1L row elements, then
Row number index and the location index identical element of the time domain impulse to be calculated response estimation are selected from L row elements, is recycled
The L selected2Individual element forms submatrix, finally obtains coefficient matrix to sub- matrix inversion.Here time domain impulse response is estimated
The location index of meter, including synchronous error, the influence also brought including system itself wave filter, receiving terminal can be set according to system
Meter estimates.
As second of optional embodiment, line number index and L selected first are selected from N × N FFT matrixes
The sub-carrier indices identical L row elements of pilot sub-carrier, that is, it is l to select line number index0, l1..., lL-1L row elements, then
Row number index and the location index of the time-domain shock response to be calculated estimation is selected to have constant offset relation δ from L row elements
Element, recycle the L selected2Individual element forms submatrix, finally obtains coefficient matrix to sub- matrix inversion.Above-mentioned δ is
The fixed value pre-set.
As the third optional embodiment, line number index is first selected to be carried with L pilot tone from N × N FFT matrixes
The sub-carrier indices identical L row elements of ripple, that is, it is l to select line number index0, l1..., lK-1L row elements, then from L rows member
Row number index and the location index identical M column elements of the time domain impulse to be calculated response estimation are selected in element, or, from L rows
The M that the location index of row number index and the time domain impulse to be calculated response estimation is selected in element has constant offset relation δ is arranged
Element, recycle the L × M element selected to form submatrix, coefficient matrix finally is obtained to sub- Matrix Calculating pseudoinverse.Above-mentioned M
≤L。
Step 4：Utilize formula hL=F-1·HLCalculate time domain impulse response estimation hL。
Step 5：N point FFT computings are done to time domain impulse response estimation using N × N FFT matrixes, obtain all subcarriers
On channel estimation in frequency domain.
, in step 1 can also a calculating part in the case where only needing selected section pilot sub-carrier in the present embodiment one
Divide the domain channel response estimation of pilot sub-carrier, without the domain channel response estimation of all pilot sub-carriers is all calculated
Out.
【Embodiment two】
The application scenarios of the present embodiment two include：Total number of sub-carriers in system is N, including virtual, pilot tone and direct current are protected
Protect subcarrier；The sum of pilot sub-carrier is K, and sub-carrier indices corresponding to N number of subcarrier are respectively 0,1 ..., N-1；Default N
× N FFT matrixes.
Channel estimation methods in the present embodiment one comprise the following steps 1~step 5.
Step 1：Calculate the domain channel response estimation H of all pilot sub-carriersK。
As optional embodiment, method of estimation can be simple, low complex degree LS channel estimations or its
The more preferable method of estimation of his performance.
Step 2：L pilot sub-carrier is selected, the domain channel response estimation for the pilot sub-carrier selected sequentially is arranged
It is classified as row vector HL, wherein L≤K, and L is more than or equal to the length of time domain impulse response.
, can be every as L ＜ K as optional embodimentIndividual pilot sub-carrier selects a pilot tone
Subcarrier, the sub-carrier indices for the L pilot sub-carrier selected are l0, l1..., lL-1, lk∈[0 N-1]。
Step 3：Transposition is carried out to N × N FFT matrixes, L × L submatrix is selected from the FFT matrixes after transposition,
Utilize submatrix generation coefficient matrix F-1。
As the first optional embodiment, row number index and the L selected are first selected from the FFT matrixes after transposition
The sub-carrier indices identical L column elements of individual pilot sub-carrier, that is, it is l to select row number index0, l1..., lL-1L column elements, so
Line number index and the location index identical element of the time domain impulse to be calculated response estimation, then profit are selected from L column elements afterwards
With the L selected2Individual element forms submatrix, finally obtains coefficient matrix to sub- matrix inversion.
As second of optional embodiment, row number index and the L selected are first selected from the FFT matrixes after transposition
The sub-carrier indices identical L column elements of individual pilot sub-carrier, that is, it is l to select row number index0, l1..., lL-1L column elements, so
Line number index and the location index of the time domain impulse to be calculated response estimation is selected to have constant offset relation δ from L column elements afterwards
Element, recycle the L selected2Individual element forms submatrix, finally obtains coefficient matrix to sub- matrix inversion.
As the third optional embodiment, row number index and L pilot tone are first selected from the FFT matrixes after transposition
The sub-carrier indices identical L column elements of carrier wave, that is, it is l to select row number index0, l1..., lK-1L column elements, then from L arrange
Line number index and the location index identical M row elements of the time domain impulse to be calculated response estimation are selected in element, or is arranged from L
Select line number index and the location index of the time domain impulse to be calculated response estimation that there is constant offset relation δ M rows in element
Element, recycle the L × M element selected to form submatrix, coefficient matrix finally is obtained to sub- Matrix Calculating pseudoinverse.Above-mentioned M
≤L。
Step 4：Utilize formula hL=HL·F-1Calculate time domain impulse response estimation hL。
Step 5：Using N × N FFT matrixes, N point FFT computings are done to time domain impulse response estimation, obtain all subcarriers
On channel estimation in frequency domain.
, in step 1 can also a calculating part in the case where only needing selected section pilot sub-carrier in the present embodiment two
Divide the domain channel response estimation of pilot sub-carrier, without the domain channel response estimation of all pilot sub-carriers is all calculated
Out.
【Embodiment three】
The application scenarios of the present embodiment three include：Total number of sub-carriers in system is N, including virtual, pilot tone and direct current are protected
Protect subcarrier；The sum of pilot sub-carrier is K, and sub-carrier indices corresponding to N number of subcarrier are respectively 0,1 ..., N-1；Default N
× N FFT matrixes.
Channel estimation methods in the present embodiment three comprise the following steps 1~step 7.
Step 1：Calculate the domain channel response estimation H of all pilot sub-carriersK。
As optional embodiment, in this step, method of estimation can be simple, the LS channel estimations of low complex degree,
It can also be the more preferable method of estimation of other performances.
Step 2：All pilot sub-carriers are divided intoGroup, each group includes L pilot sub-carrier, wherein L ＜
K, and L is more than or equal to the length of time domain impulse response.
Step 3：For each packet, L pilot sub-carrier is selected, the frequency domain channel for the pilot sub-carrier selected is rung
It is column vector H that arranged in sequence, which should be estimated,L。
Step 4：For each packet, L × L submatrix is selected from N × N FFT matrixes respectively, to the son
Matrix inversion obtains coefficient matrix F-1。
, can be optional with three kinds introduced in the step 3 of selection example one during herein for each packet generation coefficient matrix
Embodiment.
Step 5：For each packet, time domain impulse response estimation h is calculated respectivelyL, calculation formula hL=F-1·HL。
Step 6：The time domain impulse response estimation of multiple packets is weighted and averagely, obtains final time domain impulse response
Estimation.
As an alternative embodiment, can be that each packet selects identical weight, that is, by multiple points
The time domain impulse response estimation of group is directly averaged.
Step 7：N point FFT computings are done to final time domain impulse response estimation using N × N FFT matrixes, owned
Channel estimation in frequency domain on subcarrier.
In the present embodiment three, when calculating time domain impulse response estimation for each packet, with the pilot sub-carrier selected
Domain channel response estimation composition column vector exemplified by, when form row vector, be for each packet generation in above-mentioned steps 4
During matrix number, three kinds of optional embodiments that can be to be introduced in the step 3 of selection example two, using as follows in above-mentioned steps 5
Formula calculates time domain impulse response estimation：hL=HL·F-1。
In the present embodiment three, it can also be grouped just for part and calculate time domain impulse response estimation.
Using the channel estimation methods of the present invention, compared with LS+ linear interpolation algorithms, the gain more than 1.5dB can be obtained,
Fig. 3 shows the channel estimating performance of the embodiment of the present invention, is this hair compared with fine line wherein being perfect channel estimation compared with heavy line
The channel estimation of bright embodiment, dotted line are the channel estimation of LS+ linear interpolation algorithms.
Fig. 4 is the structural representation of channel estimating apparatus of the present invention.
Channel estimating apparatus of the present invention includes：First module 41 and second unit 42.
First module 41, for calculating time domain impulse response estimation.
Second unit 42, the domain channel response that all subcarriers of estimation calculating are responded using time domain impulse are estimated.
Wherein, first module 41 includes：First module 411, the second module 412 and the 3rd module 413.
First module 411, for selecting the pilot sub-carrier to be used, utilize the frequency domain for the pilot sub-carrier selected
Channel response estimates composition of vector.
Second module 412, for having using selected from the default FFT matrixes and pilot sub-carrier with selecting
There is the submatrix generation coefficient matrix of corresponding relation.
3rd module 413, by coefficient matrix and multiplication of vectors, obtain time domain impulse response estimation.
The embodiment of channel estimating apparatus of the present invention is given below.
【Example IV】
The application scenarios of the present embodiment four include：Total number of sub-carriers in system is N, including virtual, pilot tone and direct current are protected
Protect subcarrier；The sum of pilot sub-carrier is K, and sub-carrier indices corresponding to N number of subcarrier are respectively 0,1 ..., N-1；Default N
× N FFT matrixes.
Fig. 5 is the structural representation of channel estimating apparatus in the embodiment of the present invention four, and the device includes：First module 51,
Second unit 52 and third unit 53.
First module 51 specifically includes：First module 511, the second module 512 and the 3rd module 513.
First module 511, for selecting the L pilot sub-carrier to be used, the frequency domain of this L pilot sub-carrier is believed
Road response estimates arranged in sequence into column vector HL.Above-mentioned L≤K, L are more than or equal to the length of time domain impulse response.Optionally, in L
During ＜ K, the first module 511 can be everyIndividual pilot sub-carrier, select a pilot sub-carrier.
As the first optional embodiment, the second module 512 includes：First choice submodule 5121, second selects
Submodule 5122 and generation module 5123.
First choice submodule 5121, line number index is selected to be carried with L pilot tone selected from default FFT matrixes
The sub-carrier indices identical L row elements of ripple.
Second selection submodule 5122, in the L row elements selected from first choice submodule 5121, select row number index
The location index identical L column elements estimated with the time domain impulse to be calculated response, or selected from first choice submodule 5121
In the L row elements selected out, row number index and the location index of the time domain impulse to be calculated response estimation is selected to have constant offset pass
It is δ L column elements.
Submodule 5123 is generated, utilizes the L selected2Individual element forms submatrix, and to sub- matrix inversion, obtains coefficient
Matrix F-1。
As second of optional embodiment, the second module 512 includes：First choice submodule 5121, second selects
Submodule 5122 and generation module 5123.
First choice submodule 5121, for the L pilot tone for line number index being selected from default FFT matrixes with being selected
The sub-carrier indices identical L row elements of subcarrier.
Second selection submodule 5122, for selecting row number index and the time domain impulse to be calculated to respond from L row elements
The location index identical M column elements of estimation, or, row number index and time domain impulse response estimation are selected from L row elements
Location index has constant offset relation δ M column elements, wherein M≤L.
Submodule 5123 is generated, for using the L × M element composition submatrix selected, and to sub- Matrix Calculating pseudoinverse,
Obtain coefficient matrix F-1。
3rd module 513, by the way that coefficient matrix is multiplied with column vector, obtain time domain impulse response estimation.3rd module
513 utilize formula hL=F-1·HLCalculate time domain impulse response estimation hL。
Second unit 52, FFT is carried out for responding estimation to time domain impulse using default FFT matrixes, obtains institute
The domain channel response for having subcarrier is estimated.
Third unit 53, estimate for the domain channel response of calculating section or whole pilot sub-carriers.
In the present embodiment four exemplified by using the domain channel response for the pilot sub-carrier selected estimation composition column vector,
If forming row vector, the structure of channel estimating apparatus is same as shown in Figure 5, and simply the first module 511 is by the L selected
The domain channel response of pilot sub-carrier estimates arranged in sequence into row vector HL, first choice submodule 5121 is first to FFT progress
Transposition, then corresponding operating is performed based on the FFT matrixes after transposition, the 3rd module 513 utilizes formula hL=HL·F-1Calculate time domain
H is estimated in shock responseL。
【Embodiment five】
The application scenarios of the present embodiment five include：Total number of sub-carriers in system is N, including virtual, pilot tone and direct current are protected
Protect subcarrier；The sum of pilot sub-carrier is K, and sub-carrier indices corresponding to N number of subcarrier are respectively 0,1 ..., N-1；Default N
× N FFT matrixes.
Fig. 6 is the structural representation of channel estimating apparatus in the embodiment of the present invention five, and the device includes：First module 61,
Second unit 62, the unit 64 of third unit 63 and the 4th.
4th unit 64, for be divided into all K pilot sub-carriersIndividual packet, wherein being wrapped in each packet
L pilot sub-carrier is included, and L ＜ K, L are more than or equal to the length of time domain impulse response.
First module 61, for for all or all packets, calculating time domain impulse response estimation respectively.
First module 61 specifically includes：First module 611, the second module 612 and the 3rd module 613.
First module 611, for selecting the L pilot sub-carrier to be used, by the frequency for the L pilot sub-carrier selected
Domain channel response estimates arranged in sequence into column vector HL。
Second module 612, there is corresponding relation with L pilot sub-carrier for being selected from default FFT matrixes
Submatrix, and utilize submatrix generation coefficient matrix F-1。
As the first optional embodiment, the second module 612 includes：First choice submodule 6121, second selects
Submodule 6122 and generation module 6123.
First choice submodule 6121, line number index is selected to be carried with L pilot tone selected from default FFT matrixes
The sub-carrier indices identical L row elements of ripple.
Second selection submodule 6122, in the L row elements selected from first choice submodule 6121, select row number index
The location index identical L column elements estimated with the time domain impulse to be calculated response, or select what row number was indexed and calculated
The location index of time domain impulse response estimation has constant offset relation δ L column elements.
Submodule 6123 is generated, utilizes the L selected2Individual element forms submatrix, and to sub- matrix inversion, obtains coefficient
Matrix F-1。
As second of optional embodiment, the second module 612 includes：First choice submodule 6121, second selects
Submodule 6122 and generation module 6123.
First choice submodule 6121, for the L pilot tone for line number index being selected from default FFT matrixes with being selected
The sub-carrier indices identical L row elements of subcarrier.
Second selection submodule 6122, for selecting row number index and the time domain impulse to be calculated to respond from L row elements
The location index identical M column elements of estimation, or, row number index and time domain impulse response estimation are selected from L row elements
Location index has constant offset relation δ M column elements, wherein M≤L.
Submodule 6123 is generated, for using the L × M element composition submatrix selected, and to sub- Matrix Calculating pseudoinverse,
Obtain coefficient matrix F-1。
3rd module 613, for coefficient matrix to be multiplied with column vector, obtain time domain impulse response estimation hL.3rd mould
Block 613 utilizes formula hL=F-1·HLCalculate time domain impulse response estimation hL。
Second unit 62, it is average for the response estimation of obtained all time domain impulses to be weighted, when obtaining final
Domain shock response estimation, the FFT matrixes for reusing default N × N carry out FFT to final time domain impulse response estimation,
Obtain the domain channel response estimation of all subcarriers.
Third unit 63, estimate for the domain channel response of calculating section or whole pilot sub-carriers.
In the present embodiment five, for partly or entirely packet, respectively with the frequency domain channel for the L pilot sub-carrier selected
Exemplified by response estimation composition column vector, if composition row vector, the structure of channel estimating apparatus is same as shown in Figure 6, simply
First module 611 embarks on journey the domain channel response estimation arranged in sequence for the L pilot sub-carrier selected for each packet
Vectorial HL, first choice submodule 6121 first carries out transposition to default FFT matrixes, then is performed based on the FFT matrixes after transposition
Corresponding operating, the 3rd module 613 utilize formula hL=HL·F-1Calculate time domain impulse response estimation hL。
It should be understood that the particular order or level of the step of during disclosed are the examples of illustrative methods.Based on setting
Count preference, it should be appreciated that during the step of particular order or level can be in the feelings for the protection domain for not departing from the disclosure
Rearranged under condition.Appended claim to a method gives the key element of various steps with exemplary order, and not
It is to be limited to described particular order or level.
In above-mentioned detailed description, various features combine in single embodiment together, to simplify the disclosure.No
This open method should be construed to reflect such intention, i.e. the embodiment of theme claimed needs clear
The more features of feature stated in each claim to Chu.On the contrary, that reflected such as appended claims
Sample, the present invention are in the state fewer than whole features of disclosed single embodiment.Therefore, appended claims is special
This is expressly incorporated into detailed description, and wherein each claim is alone as the single preferred embodiment of the present invention.
Described above includes the citing of one or more embodiments.Certainly, in order to above-described embodiment is described and description portion
The all possible combination of part or method is impossible, but it will be appreciated by one of ordinary skill in the art that each implementation
Example can do further combinations and permutations.Therefore, embodiment described herein is intended to fall into appended claims
Protection domain in all such changes, modifications and variations.In addition, with regard to the term used in specification or claims
"comprising", the mode that covers of the word are similar to term " comprising ", just as " including " solved in the claims as link word
As releasing.In addition, the use of any one term "or" in the specification of claims is to represent " non-exclusionism
Or ".
Claims (18)
1. a kind of channel estimation methods, it is characterised in that this method includes：
Calculate time domain impulse response estimation；With,
The domain channel response that all subcarriers of estimation calculating are responded using time domain impulse is estimated；
Wherein, the calculating time domain impulse response estimation includes：
Select the pilot sub-carrier to be used；
Estimate composition of vector using the domain channel response for the pilot sub-carrier selected；
There is corresponding close using selected from the default Fourier transformation FFT matrixes and pilot sub-carrier with selecting
The submatrix generation coefficient matrix of system；
By the coefficient matrix and the multiplication of vectors, time domain impulse response estimation is obtained；
The domain channel response estimation arranged in sequence for the L pilot sub-carrier selected is formed into the vector；Wherein L≤K, K
For the sum of pilot sub-carrier, L is more than or equal to the length of time domain impulse response；
During the generation coefficient matrix：
The sub-carrier indices identical L rows of line number index and the L pilot sub-carrier are selected from the default FFT matrixes
Element；
Row number index and the location index identical L of the time domain impulse to be calculated response estimation is selected to arrange from the L row elements
Element, or, the location index for selecting row number index to estimate with the time domain impulse to be calculated response from the L row elements has solid
Determine the L column elements of offset relationship；
Utilize the L selected2Individual element forms submatrix；
To sub- matrix inversion, coefficient matrix is obtained.
2. the method as described in claim 1, it is characterised in that this method also includes：Calculating section or whole pilot sub-carriers
Domain channel response estimation.
3. the method as described in claim 1, it is characterised in that work as L<During K, everyIndividual pilot sub-carrier, selection
One pilot sub-carrier.
4. the method as described in claim 1, it is characterised in that this method also includes：All K pilot sub-carriers are divided intoIndividual packet, wherein each packet includes L pilot sub-carrier, and L<K, L are more than or equal to the length of time domain impulse response
Degree；
For some or all packets, the step of calculating time domain impulse response is estimated is performed respectively；
The domain channel response estimation that all subcarriers of estimation calculating are responded using time domain impulse, including：To obtained institute
There is time domain shock response estimation to be weighted average, obtain final time domain impulse response estimation, utilize the final time domain
Shock response estimation calculates the domain channel response estimation of all subcarriers；
The domain channel response estimation arranged in sequence for the L pilot sub-carrier selected is formed into the vector.
5. the method as described in claim 1 or 4, it is characterised in that or, it is described generation coefficient matrix when：
Transposition is carried out to the default FFT matrixes；
The sub-carrier indices identical L row members of row number index and the L pilot sub-carrier are selected from the FFT matrixes after transposition
Element；
Line number index and the location index identical L rows of the time domain impulse to be calculated response estimation are selected from the L column elements
Element, or, the location index for selecting line number index to estimate with the time domain impulse to be calculated response from the L column elements has solid
Determine the L column elements of offset relationship；
Utilize the L selected2Individual element forms submatrix；
To sub- matrix inversion, coefficient matrix is obtained.
6. the method as described in claim 1 or 4, it is characterised in that or, it is described generation coefficient matrix when：
The sub-carrier indices identical L rows of line number index and the L pilot sub-carrier are selected from the default FFT matrixes
Element；
Row number index and the location index identical M of the time domain impulse to be calculated response estimation is selected to arrange from the L row elements
Element, or, select row number index and the location index of the time domain impulse to be calculated response estimation to have from the L row elements
The M column elements of constant offset relation, wherein M≤L；
Submatrix is formed using the L × M element selected；
To sub- Matrix Calculating pseudoinverse, coefficient matrix is obtained.
7. the method as described in claim 1 or 4, it is characterised in that or, it is described generation coefficient matrix when：
Transposition is carried out to the default FFT matrixes；
The sub-carrier indices identical L row members of row number index and the L pilot sub-carrier are selected from the FFT matrixes after transposition
Element；
Line number index and the location index identical M rows of the time domain impulse to be calculated response estimation are selected from the L column elements
Element, or, select line number index and the location index of the time domain impulse to be calculated response estimation to have from the L column elements
The M row elements of constant offset relation, wherein M≤L；
Submatrix is formed using the L × M element selected；
To sub- Matrix Calculating pseudoinverse, coefficient matrix is obtained.
8. the method as described in claim 1, it is characterised in that the default FFT matrixes are N × N matrix, and wherein N is sub
The sum of carrier wave.
9. method as claimed in claim 8, it is characterised in that use the default FFT matrixes, estimate to time domain impulse response
Meter carries out FFT, calculates the domain channel response estimation of all subcarriers.
10. a kind of channel estimating apparatus, it is characterised in that the device includes：
First module, for calculating time domain impulse response estimation；With,
Second unit, for calculating the domain channel response estimation of all subcarriers using time domain impulse response estimation；
Wherein described first module includes：
First module, for selecting the pilot sub-carrier to be used, utilize the domain channel response for the pilot sub-carrier selected
Estimate composition of vector；
Second module, for utilizing selected from the default Fourier transformation FFT matrixes and pilot sub-carrier with selecting
Submatrix generation coefficient matrix with corresponding relation；
3rd module, for by the coefficient matrix and the multiplication of vectors, obtaining time domain impulse response estimation；
Wherein, the domain channel response of the L pilot sub-carrier selected is estimated arranged in sequence into described by first module
Vector；Wherein and L≤K, K are the sum of pilot sub-carrier, and L is more than or equal to the length of time domain impulse response；
Wherein, second module includes：
First choice submodule, the son load of line number index and the L pilot sub-carrier is selected from the default FFT matrixes
Ripple indexes identical L row elements；
Second selection submodule, row number index and the position of the time domain impulse to be calculated response estimation are selected from the L row elements
Index identical L column elements are put, or select row number index to estimate with the time domain impulse to be calculated response from the L row elements
Location index have the L column elements of constant offset relation；
Submodule is generated, utilizes the L selected2Individual element forms the submatrix, and the submatrix is inverted, and obtains described
Coefficient matrix.
11. device as claimed in claim 10, it is characterised in that the device also includes：Third unit, for calculating section or
The domain channel response estimation of whole pilot sub-carriers.
12. device as claimed in claim 10, it is characterised in that work as L<During K, first module everyIt is individual
Carrier wave, select a pilot sub-carrier.
13. device as claimed in claim 10, it is characterised in that the device also includes：Unit the 4th, for all K to be led
Frequency subcarrier is divided intoIn each packet include L pilot sub-carrier, and L<K, L ring more than or equal to time domain impulse
The length answered；
The first module is directed to some or all packets, performs the operation for calculating time domain impulse response estimation respectively；
The second unit is first weighted averagely to obtained all time domain impulses response estimation, obtains final time domain impulse
Response estimation, final time domain impulse is recycled to respond the domain channel response estimation that estimation calculates all subcarriers.
14. the device as described in claim 10 or 13, it is characterised in that or, second module includes：
First choice submodule, transposition is carried out to the default FFT matrixes, row number rope is selected from the FFT matrixes after transposition
Draw the sub-carrier indices identical L column elements with the L pilot sub-carrier；
Second selection submodule, line number index and the position of the time domain impulse to be calculated response estimation are selected from the L column elements
Index identical L row elements are put, or select line number index to estimate with the time domain impulse to be calculated response from the L column elements
Position there is the L row elements of constant offset relation；
Generation module, utilize the L selected2Individual element forms the submatrix, and the submatrix is inverted, and obtains the system
Matrix number.
15. the device as described in claim 10 or 13, it is characterised in that or, second module includes：
First choice submodule, the sub-carrier indices phase of line number index and L pilot sub-carrier is selected from default FFT matrixes
Same L row elements；
Second selection submodule, row number index and the position of the time domain impulse to be calculated response estimation are selected from the L row elements
Index identical M column elements are put, or, select row number index to estimate with the time domain impulse to be calculated response from the L row elements
The location index of meter has the M column elements of constant offset relation, wherein M≤L；
Submodule is generated, the submatrix is formed using the L × M element selected, and pseudoinverse is asked to the submatrix, is obtained
The coefficient matrix.
16. the device as described in claim 10 or 13, it is characterised in that or, second module includes：
First choice submodule, transposition is carried out to FFT matrixes, and row number index and the L are selected from the FFT matrixes after transposition
The sub-carrier indices identical L column elements of pilot sub-carrier；
Second selection submodule, line number index and the position of the time domain impulse to be calculated response estimation are selected from the L column elements
Index identical M row elements are put, or, select line number index to estimate with the time domain impulse to be calculated response from the L column elements
The location index of meter has the M row elements of constant offset relation, wherein M≤L；
Generation module, the submatrix is formed using the L × M element selected, and pseudoinverse is asked to the submatrix, obtain institute
State coefficient matrix.
17. device as claimed in claim 10, it is characterised in that the default FFT matrixes be N × N matrix, wherein N
For the sum of subcarrier.
18. device as claimed in claim 17, it is characterised in that the second unit uses the default FFT matrixes, right
Time domain impulse response estimation carries out FFT, calculates the domain channel response estimation of all subcarriers.
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