CN104883327B - Channel estimation methods and system based on two-dimensional interpolation - Google Patents
Channel estimation methods and system based on two-dimensional interpolation Download PDFInfo
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Abstract
The present invention provides a kind of channel estimation methods and system based on two-dimensional interpolation, and wherein method includes the following steps: that (1) establishes the channel model of ofdm system；(2) pattern is inserted into using diamond shape pilot tone, is inserted into frequency pilot sign in the time domain of the OFDM symbol of the channel model and frequency domain direction respectively, obtains the originally transmitted signal of two-dimensional interpolation；(3) the originally transmitted signal received to receiving end institute carries out channel estimation and obtains pilot point position and its estimation channel value；(4) diamond shape pilot tone plane is divided by two regular sub- pilot tone planes according to the estimation channel value, channel response interpolation is carried out to every sub- pilot tone plane respectively and calculates average value, obtain channel response estimated value.Technical solution of the present invention combines improved bicubic two-dimensional interpolation method to carry out channel estimation, improves the performance of channel estimation, and algorithm complexity is lower, be easy to implement using diamond shape pilot tone insertion pattern.
Description
Technical field
The present invention relates to fields of communication technology, more particularly to a kind of channel estimation methods based on two-dimensional interpolation and are
System.
Background technique
In LTE standard, downlink takes orthogonal frequency division multiplexing (OFDM) to modulate, and uplink takes single-carrier frequency division multiple access (SC-
FDMA) modulation system.OFDM is a kind of multi-carrier modulation, overcomes channel by reducing and eliminating the influence of intersymbol interference
Frequency selective fading then modulated respectively with N number of subsignal N number of the basic principle is that signal is divided into N number of subsignal
Mutually orthogonal subcarrier.Since the frequency spectrum of subcarrier is overlapped, thus available higher spectrum efficiency.
Intersymbol interference caused by the multi-path delay spread of wireless channel (ISI) seriously limits the number on wireless channel
According to transmission rate, and OFDM technology can effectively inhibit intersymbol interference, so that earns widespread respect is since OFDM is to each subcarrier
Between orthogonality requirement so that the receiving-transmitting sides of ofdm system must stringent synchronization (including carrier synchronization, sampling clock are synchronous),
There must be sufficiently accurate channel estimation due to the time variation of wireless channel simultaneously, most of ofdm systems, which all use, to be based on
The channel estimation methods of pilot tone training signal, i.e., using known pilot signal progress channel rough estimate is inserted into, then by inserting
Value method finds out the total regression of channel.
Based on the channel estimation of pilot aided due to having the characteristics that simple, accurate and high stability, it is most normal to become OFDM
Channel estimation mode.So-called pilot tone is some special data, the position of these data and numerical value known to receiving end.By this
A little data are inserted into initial data according to certain principle, then carry out IDFT transformation with initial data.In receiving end,
After over-sampling and DFT transform, channel rough estimate is carried out using known pilot signal is inserted into, then passes through certain processing means
(such as interpolation, filtering) finds out the total regression of channel, to carry out balanced, raising system performance to signal is received.
When having the characteristics that due to ofdm system, frequency two dimension, so the pilot tone based on two-dimensional model can better adapt to letter
Decline of the road in time domain and frequency domain has lower pilot density and the higher availability of frequency spectrum.So being based on pilot aided
Channel estimation methods can be divided into two steps, the channel value at first step estimating pilot frequency point, according to these values, estimated data position
The channel value at place.It needs to carry out interpolation to known estimated value in second step estimation, to obtain the total regression of channel.
Common interpolation method includes one-dimensional interpolation and two-dimensional interpolation, and wherein two-dimensional interpolation includes network node interpolation and dissipates
Point interpolation two types.Network node interpolation includes closest interpolation, fragment linearity interpolation, bilinear interpolation and bicubic interpolation
Deng.Scatterplot interpolation includes amendment Shepherd method etc..The complexity of different interpolation methods obtained estimated accuracy and realization
Also it is not quite similar.
The channel estimation methods of pilot aided mainly use four kinds of pilot frequency modes such as bulk, pectination, trellis and diamond shape at present.
When carrying out interpolation, one-dimensional interpolation is taken to make accuracy of channel estimation lower, although two-dimentional scatterplot interpolation accuracy is higher,
The complexity of realization is also correspondingly higher.
In conclusion existing interpolation method, it is difficult to guarantee the performance of channel estimation, precision of channel estimation is lower, algorithm
Complexity is higher, is unfavorable in realization.
Summary of the invention
Based on this, it is necessary in view of the above technical problems, provide a kind of complexity is low, estimated accuracy it is higher based on two dimension
The channel estimation methods and system of interpolation.
A kind of channel estimation methods based on two-dimensional interpolation, include the following steps:
(1) channel model of ofdm system is established；
(2) pattern is inserted into using diamond shape pilot tone, respectively in the time domain and frequency domain direction of the OFDM symbol of the channel model
Upper insertion frequency pilot sign obtains the originally transmitted signal of two-dimensional interpolation；
(3) the originally transmitted signal received to receiving end institute carries out channel estimation and obtains pilot point position and its estimation
Channel value；
(4) diamond shape pilot tone plane is divided by two regular sub- pilot tone planes according to the estimation channel value, it is right respectively
Every sub- pilot tone plane carries out channel response interpolation and calculates average value, obtains channel response estimated value.
A kind of channel estimation system based on two-dimensional interpolation, comprising:
Channel model creation module, for establishing the channel model of ofdm system；
Pilot tone model creation module is accorded in the OFDM of the channel model respectively for being inserted into pattern using diamond shape pilot tone
Number time domain and frequency domain direction on be inserted into frequency pilot sign, obtain the originally transmitted signal of two-dimensional interpolation；
Channel rough estimate module is led for carrying out channel estimation to the received originally transmitted signal of receiving end institute
Frequency point position and its estimation channel value；
Interpolation processing module is led for diamond shape pilot tone plane to be divided into two regular sons according to the estimation channel value
Frequency plane carries out channel response interpolation to every sub- pilot tone plane respectively and calculates average value, obtains channel response estimated value.
Above-mentioned channel estimation methods and system based on two-dimensional interpolation, using diamond shape pilot tone insertion pattern insertion pilot tone symbol
Number, after carrying out channel rough estimate, diamond shape pilot tone plane is divided into two regular sub- pilot tone planes, it is improved by taking
Bicubic two-dimensional interpolation method carries out channel estimation, carries out channel response interpolation to every sub- pilot tone plane respectively and calculates average
Value obtains final channel response estimated value, improves the performance of channel estimation, and algorithm complexity is lower, is easy to implement.
Detailed description of the invention
Fig. 1 is that the present invention is based on the channel estimation methods flow charts of two-dimensional interpolation；
Fig. 2 is ofdm system model schematic；
Fig. 3 is diamond shape pilot tone schematic shapes；
Fig. 4 is the second sub- pilot tone floor map；
Fig. 5 is that the present invention is based on the channel estimation system structural schematic diagrams of two-dimensional interpolation；
Fig. 6 is the structural schematic diagram of the interpolation processing module of one embodiment.
Specific embodiment
With reference to the accompanying drawing to the specific embodiment of the channel estimation methods based on two-dimensional interpolation and system of the invention
It is described in detail.
Refering to what is shown in Fig. 1, Fig. 1 is to include the following steps: the present invention is based on the channel estimation methods flow chart of two-dimensional interpolation
(1) channel model of ofdm system is established.
It is that channel width is divided into multiple sub- letters in frequency domain using Fast Fourier Transform (FFT) IFFT in ofdm system
Road is adjusted on every sub-channels, mutually orthogonal between each subcarrier, parallel transmission with a subcarrier.
Refering to what is shown in Fig. 2, Fig. 2 is ofdm system model schematic.Binary data after coding by modulation (such as:
QBSK it) is transformed into frequency domain data X (k), k=0,1 ..., N-1, N are the carrier numbers of OFDM.After frequency domain is inserted into pilot tone, utilize
X (k) is modulated into OFDM and met by IFFT；Then OFDM symbol is inserted into cyclic prefix CP in front end, forms protection interval, length
It should be greater than the maximum delay τ of channelmax, to eliminate intersymbol interference ISI.The discrete form that OFDM meets after addition cyclic prefix
Such as following formula:
In formula, X (k) is the data symbol transmitted on k-th of subcarrier, it is generated by QBSK or other modulation systems
Replicate data, x (n) are the OFDM symbol at n moment.Channel is sent into after signal parallel serial conversion.After receiving end removes cyclic prefix, by
FFT transform translates the signals into back frequency domain and extracts pilot signal for channel estimation.After channel compensation, frequency domain data is solved
It adjusts, decodes with restoring user data.
In one embodiment, the step (1) can specifically include following process:
Multiple carrier channel model is established, each path reaches receiving end respectively with different amplitudes, phase, frequency displacement and time delay,
The envelope in path is in rayleigh distributed, it may be assumed that
A in formulal、fD,l、And τlIt is amplitude, Doppler frequency shift, phase and the time delay of channel respectively,
For rectangular pulse.
(2) pattern is inserted into using diamond shape pilot tone, respectively in the time domain and frequency domain direction of the OFDM symbol of the channel model
Upper insertion frequency pilot sign obtains the originally transmitted signal of two-dimensional interpolation.
The channel frequency response CFR of ofdm system can be regarded as a 2D signal, thus can be in time domain and frequency domain
Pilot signal is regularly inserted into both direction.
Insertion of the pilot tone in OFDM symbol is considered as the two dimension sampling to channel frequency response, therefore pilot tone insertion needs
Meeting sampling thheorem to avoid frequency aliasing, in coherence bandwidth BcInterior and coherence time TcInside at least to be inserted into a pilot tone
Symbol.
As an implementation, when, the interval Nyquist df, dt on frequency direction and channel correlation bandwidth Bc, phase
Dry time TcBetween must satisfy following formula:
In formula, τmax、Respectively maximum delay and maximum doppler frequency, Δ f, TsymbolFor the carrier wave of ofdm system
Interval and mark space.
Relative to using pilot frequency modes such as bulk, pectination, trellis and diamond shapes, can be improved using diamond shape pilot tone insertion pattern
The performance of channel estimation uses the pilot tone shape of diamond shape pilot tone as shown in figure 3, Fig. 3 shows for diamond shape pilot tone shape in the present invention
It is intended to, in time, frequency two-dimension pilot frequency plane, white box is user data, and grey box is cell particular interference signal.
(3) the originally transmitted signal received to receiving end institute carries out channel estimation and obtains pilot point position and its estimation
Channel value.
It in this step, is the rough estimate for completing channel, estimating pilot frequency point position and its letter at estimated data position
Road value.
In one embodiment, the estimation procedure of the step (3) mainly includes the following:
It is received to receiving end institute using channel estimation methods according to the frequency pilot sign being inserted into the originally transmitted signal
The pilot point of the originally transmitted signal carries out channel estimation, obtains channel estimation value.
Channel estimation process based on pilot aided, channel estimation, two-dimensional interpolation including pilot point.Here, by
The frequency pilot sign being inserted into the useful data of transmission, the channel estimation results of available pilot frequency locations；
Specifically, estimating the channel frequency response of pilot point, the method for channel estimation has very much, as least square is estimated
Meter, linear minimum respectively estimation, maximal possibility estimation or Bayesian Estimation etc.；By taking least square (LS) as an example, underdraw letter
Road estimation procedure.
If pilot symbol transmitted is p (k), frequency pilot sign position p ' (k) is received according to LS rule and obtains the letter at pilot point
Road estimated value are as follows:
In formula, NpFor the number of pilot symbols of insertion, L is pilot symbol interval.
(4) diamond shape pilot tone plane is divided by two regular sub- pilot tone planes according to the estimation channel value, it is right respectively
Every sub- pilot tone plane carries out channel response interpolation and calculates average value, obtains channel response estimated value.
In this step, using the channel rough estimate of pilot frequency locations as a result, interpolation is carried out to known estimated value, by interior
It inserts and obtains the total regression estimated result of the channel of useful data position, complete final channel response estimation.
For the advantage for making full use of the frequency and time of pilot tone equidistant, present invention improves over bicubic interpolation (Bicubic
Interpolation) method, and for carrying out interpolated channel estimation.
Bicubic interpolation is most common interpolation method in two-dimensional space, and in this approach, function f is in point (x, y)
Value can be obtained by the weighted average of 16 sampled points nearest in rectangular mesh, be needed herein using two multinomials
Interpolation cubic function, each direction use one.In mathematics, bicubic interpolation is interpolated data point on two-dimensional regular grid
Cube interpolation extension, relevant interpolation surface is more smooth than bilinear interpolation and closest interpolation.
The present invention improves bicubic two-dimensional interpolation algorithm, estimates the total regression of channel, and improved interpolation algorithm is mainly such as
Under: diamond shape pilot tone plane is divided into two parts first；Then in every sub- pilot tone plane using bicubic interpolation algorithm into
The estimation of row channel response；Channel response twice is averaged again, seeks final channel response estimation.
Due to being better than bulk, pectination, trellis and diamond shape pilot frequency mode using diamond shape pilot frequency mode, channel estimation can be improved
Performance, but this pilot frequency mode is not fully uniform in the distribution of time orientation and frequency domain direction, thus is not suitable for directly adopting
Take gridding interpolation method.The present invention takes the pilot frequency mode of diamond shape when being inserted into pilot signal.In order to more preferably realize Interpolate estimation,
By improving bicubic interpolation and being used for channel estimation, pilot tone is split into two grid pilot tones, then again respectively in each net
Channel estimation, then averaged are carried out using bicubic interpolation in network pilot tone, since the two grid pilot tones are then in time side
It is evenly distributed to frequency domain direction, obtains that interpolation curved surface is more smooth, and Interpolate estimation precision is higher, together using bicubic interpolation
When, by the way that pilot tone will be split into two grid pilot tones, the uniformity of network interpolation can be made full use of, so that interpolation algorithm is multiple
Miscellaneous degree substantially reduces, and is easy to implement.
In one embodiment, the step (4) can specifically include following steps:
(4-1) obtains diamond shape pilot tone plane according to the estimation channel value, and diamond shape pilot tone plane is divided into the square of rule
The sub- pilot tone plane of the first of shape mesh shape and the second sub- pilot tone plane.
As an implementation, the first sub- pilot tone that diamond shape pilot tone plane is divided into the rectangular mesh shape of rule is put down
The step of face and the second sub- pilot tone plane, may include as follows:
1) odd-numbered line and even number line where the cell particular interference signal in diamond shape pilot tone plane are extracted respectively, are constituted
The the equally distributed first sub- pilot tone and the second sub- pilot tone of rule.
It, below will be with refering to what is shown in Fig. 3, odd-numbered line and even number line where cell particular interference signal in pilot tone plane
Shape shown in Fig. 3 is illustrated.
2) odd-numbered line where the cell particular interference signal of the first sub- pilot tone in diamond shape pilot tone is retained and removes idol
Several rows of interference signals constitute the first sub- pilot tone plane of rectangular mesh shape.
Odd-numbered line where cell particular interference signal is kept down, and even number line interference signal has been removed.
3) even number line where the cell particular interference signal of the second sub- pilot tone in diamond shape pilot tone is retained and removes surprise
Several rows of interference signals constitute the second sub- pilot tone plane of rectangular mesh shape.
Refering to what is shown in Fig. 4, Fig. 4 is the second sub- pilot tone floor map, as seen from the figure, cell particular interference signal institute
Even number line keep down, odd-numbered line interference signal has been removed.
By can be seen that the rectangular mesh plane that two sub- pilot tones are all rules after dividing, so as to utilize double three
Secondary interpolation algorithm carries out channel estimation.
(4-2) carries out channel using bicubic interpolation algorithm in the first sub- pilot tone plane and the second sub- pilot tone plane respectively
Response estimation, obtains the first response estimation value and the second response estimation value.
By the available continuous interpolating function of bicubic interpolation, its first-order partial derivative is continuous, and intersects
Derivative everywhere continuous.
Assuming that function f and its derivative fx, fyAnd fx,yIn four points (0,0), (1,0), the functional value on (0,1) and (1,1)
It is known that and functional value be plural number, then interpolation surface can be write as:
Then interpolation problem, which is equivalent to, solves 16 coefficient aij.Functional value is substituted into p (x, y), is had:
1.f (0,0)=p (0,0)=a00
2.f (1,0)=p (1,0)=a00+a10+a20+a30
3.f (0,1)=p (0,1)=a00+a01+a02+a03
4.
Similar, by the local derviation on the direction x and y, following 8 equations can be obtained:
5.fx(0,0)=px(0,0)=a10
6.fx(1,0)=px(1,0)=a10+2a20+3a30
7.fx(0,1)=px(0,1)=a10+a11+a12+a13
8.
9.fy(0,0)=py(0,0)=a01
10.fy(1,0)=py(1,0)=a01+a11+a21+a31
11.fy(0,1)=py(0,1)=a01+2a02+3a03
12.
Similarly, following four equation can be obtained about the cross derivative of xy:
13.fxy(0,0)=pxy(0,0)=a11
14.fxy(1,0)=pxy(1,0)=a11+2a21+3a31
By solving above-mentioned 16 systems of linear equations, available 16 coefficient aij.The p (x, y) obtained in this way is in section
[0,1] × [0,1] is continuous, and has continuous derived function.
Bicubic interpolation arbitrary intervals grid can be transferred through such bicubic surface and link together, it is ensured that derivative energy
Coincidence boundary requirement.
It, can be by being obtained in the field functional value approximation of these points if function is unknown in the derivative value of four points.It will
All coefficients form a vector:
α=[a00a10a20a30a01a11a21a31a02a12a22a32a03a13a23a33]T
It enables
X=[f (0,0) f (1,0) f (0,1) f (1,1) fx(0,0)fx(1,0)fx(0,1)fx(1,1)fy(0,0)fy(1,0)
fy(0,1)fy(1,1)fxy(0,0)fxy(1,0)fxy(0,1)fxy(1,1)]TThen problem becomes to seek the solution of system of linear equations A α=x.
It is corresponding with being combined along frequency interval using the frequency response values for three adjacent pilot frequencies positions having been estimated that
Three different coordinate points find out one and pass through this 3 points third degree curve, which meets two curves adjacent thereto
Junction is smooth (i.e. first derivative of two curves on a certain position is equal), according to calculated third degree curve to it
Between Data Position frequency response values carry out interpolation.
(4-3) calculates the average value of first response estimation value and the second response estimation value, obtains the letter of ofdm system
Road response estimation value.
To sum up embodiment estimated in the enterprising row interpolations of two sub- pilot tone two-dimensional surfaces respectively using bicubic interpolation twice,
And it is averaged to obtain final channel response estimation.Compared with other interpolation methods, what which obtained
Interpolation curved surface is more smooth, and Interpolate estimation precision is higher.Meanwhile prismatic pilot tone is split as two regular rectangle planes, it can
To make full use of the uniformity of network interpolation, substantially reduce interpolation algorithm complexity.
Refering to what is shown in Fig. 5, Fig. 5 is that the present invention is based on the channel estimation system structural schematic diagrams of two-dimensional interpolation, comprising:
Channel model creation module, for establishing the channel model of ofdm system；
Pilot tone model creation module is accorded in the OFDM of the channel model respectively for being inserted into pattern using diamond shape pilot tone
Number time domain and frequency domain direction on be inserted into frequency pilot sign, obtain the originally transmitted signal of two-dimensional interpolation；
Channel rough estimate module is led for carrying out channel estimation to the received originally transmitted signal of receiving end institute
Frequency point position and its estimation channel value；
Interpolation processing module is led for diamond shape pilot tone plane to be divided into two regular sons according to the estimation channel value
Frequency plane carries out channel response interpolation to every sub- pilot tone plane respectively and calculates average value, obtains channel response estimated value.
In one embodiment, the channel model creation module is further used for establishing the multicarrier letter of ofdm system
Road model, wherein each path reaches receiving end respectively with different amplitudes, phase, frequency displacement and time delay, and the envelope in path is in Rayleigh
Distribution.
In one embodiment, the channel rough estimate module is further used for inserting according in the originally transmitted signal
The frequency pilot sign entered, using channel estimation methods to receiving end the received originally transmitted signal pilot point carry out channel
Estimation obtains channel estimation value；
Wherein, the channel estimation methods include least squares estimate, linear minimum divides equally the estimation technique, maximum likelihood is estimated
Meter method or Bayes' assessment.
In one embodiment, refering to what is shown in Fig. 6, Fig. 6 is the structural schematic diagram of the interpolation processing module of one embodiment,
It specifically includes that
Pilot tone division unit draws diamond shape pilot tone plane for obtaining diamond shape pilot tone plane according to the estimation channel value
It is divided into the first sub- pilot tone plane and the second sub- pilot tone plane of the rectangular mesh shape of rule；
Interpolation process unit, for utilizing bicubic interpolation in the first sub- pilot tone plane and the second sub- pilot tone plane respectively
Algorithm carries out channel response estimation, obtains the first response estimation value and the second response estimation value；
Average calculation unit is obtained for calculating the average value of first response estimation value and the second response estimation value
The channel response estimated value of ofdm system.
As an implementation, diamond shape pilot tone plane is divided into the rectangular mesh of rule by the pilot tone division unit
The process of the sub- pilot tone plane of the first of shape and the second sub- pilot tone plane includes:
The odd-numbered line and even number line where the cell particular interference signal in diamond shape pilot tone plane are extracted respectively, constitute rule
The equally distributed first sub- pilot tone and the second sub- pilot tone then；
Odd-numbered line where the cell particular interference signal of the first sub- pilot tone in diamond shape pilot tone is retained and removes even number
Row interference signal constitutes the first sub- pilot tone plane of rectangular mesh shape；
Even number line where the cell particular interference signal of the second sub- pilot tone in diamond shape pilot tone is retained and removes odd number
Row interference signal constitutes the second sub- pilot tone plane of rectangular mesh shape.
The channel estimation system based on two-dimensional interpolation of the invention and the channel estimation side of the invention based on two-dimensional interpolation
Method corresponds, in the technical characteristic and its advantages of the embodiment elaboration of the above-mentioned channel estimation methods based on two-dimensional interpolation
Suitable for the embodiment of the channel estimation system based on two-dimensional interpolation, hereby give notice that.
The embodiments described above only express several embodiments of the present invention, and the description thereof is more specific and detailed, but simultaneously
Limitations on the scope of the patent of the present invention therefore cannot be interpreted as.It should be pointed out that for those of ordinary skill in the art
For, without departing from the inventive concept of the premise, various modifications and improvements can be made, these belong to guarantor of the invention
Protect range.Therefore, the scope of protection of the patent of the invention shall be subject to the appended claims.
Claims (8)
1. a kind of channel estimation methods based on two-dimensional interpolation, which comprises the steps of:
(1) channel model of ofdm system is established；
(2) pattern is inserted into using diamond shape pilot tone, is inserted in the time domain of the OFDM symbol of the channel model and frequency domain direction respectively
Enter frequency pilot sign, obtains the originally transmitted signal of two-dimensional interpolation；
(3) the originally transmitted signal received to receiving end institute carries out channel estimation and obtains pilot point position and its estimation channel
Value；
(4) diamond shape pilot tone plane is divided by two regular sub- pilot tone planes according to the estimation channel value, respectively to each
Sub- pilot tone plane carries out channel response interpolation and calculates average value, obtains channel response estimated value, includes the following steps:
Diamond shape pilot tone plane is obtained according to the estimation channel value, diamond shape pilot tone plane is divided into the rectangular mesh shape of rule
The first sub- pilot tone plane and the second sub- pilot tone plane；Respectively using double in the first sub- pilot tone plane and the second sub- pilot tone plane
Cubic interpolation algorithm carries out channel response estimation, obtains the first response estimation value and the second response estimation value；Calculate described first
The average value of response estimation value and the second response estimation value obtains the channel response estimated value of ofdm system.
2. the channel estimation methods according to claim 1 based on two-dimensional interpolation, which is characterized in that step (1) packet
It includes:
Establish the multiple carrier channel model of ofdm system, wherein each path is respectively with different amplitudes, phase, frequency displacement and time delay
Receiving end is reached, the envelope in path is in rayleigh distributed.
3. the channel estimation methods according to claim 1 based on two-dimensional interpolation, which is characterized in that step (3) packet
It includes:
It is received to receiving end institute described using channel estimation methods according to the frequency pilot sign being inserted into the originally transmitted signal
The pilot point of originally transmitted signal carries out channel estimation, obtains channel estimation value；
Wherein, the channel estimation methods include least squares estimate, the linear minimum respectively estimation technique, maximum likelihood estimate
Or Bayes' assessment.
4. the channel estimation methods according to claim 1 based on two-dimensional interpolation, which is characterized in that in the step (4),
The step of diamond shape pilot tone plane is divided into the first sub- pilot tone plane and the second sub- pilot tone plane of the rectangular mesh shape of rule
Include:
The odd-numbered line and even number line where the cell particular interference signal in diamond shape pilot tone plane are extracted respectively, composition rule
Equally distributed first sub- pilot tone and the second sub- pilot tone；
Odd-numbered line where the cell particular interference signal of the first sub- pilot tone in diamond shape pilot tone is retained and removes even number line and is done
Signal is disturbed, the first sub- pilot tone plane of rectangular mesh shape is constituted；
Even number line where the cell particular interference signal of the second sub- pilot tone in diamond shape pilot tone is retained and removes odd-numbered line and is done
Signal is disturbed, the second sub- pilot tone plane of rectangular mesh shape is constituted.
5. a kind of channel estimation system based on two-dimensional interpolation characterized by comprising
Channel model creation module, for establishing the channel model of ofdm system；
Pilot tone model creation module, for being inserted into pattern using diamond shape pilot tone, respectively in the OFDM symbol of the channel model
It is inserted into frequency pilot sign on time domain and frequency domain direction, obtains the originally transmitted signal of two-dimensional interpolation；
Channel rough estimate module obtains pilot point for carrying out channel estimation to the received originally transmitted signal of receiving end institute
Position and its estimation channel value；
Interpolation processing module is put down for diamond shape pilot tone plane to be divided into two regular sub- pilot tones according to the estimation channel value
Face carries out channel response interpolation to every sub- pilot tone plane respectively and calculates average value, obtains channel response estimated value；
The interpolation processing module includes:
Diamond shape pilot tone plane is divided by pilot tone division unit for obtaining diamond shape pilot tone plane according to the estimation channel value
The the first sub- pilot tone plane and the second sub- pilot tone plane of the rectangular mesh shape of rule；
Interpolation process unit, for utilizing bicubic interpolation algorithm in the first sub- pilot tone plane and the second sub- pilot tone plane respectively
Channel response estimation is carried out, the first response estimation value and the second response estimation value are obtained；
Average calculation unit obtains OFDM for calculating the average value of first response estimation value and the second response estimation value
The channel response estimated value of system.
6. the channel estimation system according to claim 5 based on two-dimensional interpolation, which is characterized in that the channel model wound
Block is modeled, is further used for establishing the multiple carrier channel model of ofdm system, wherein each path is respectively with different amplitudes, phase
Position, frequency displacement and time delay reach receiving end, and the envelope in path is in rayleigh distributed.
7. the channel estimation system according to claim 5 based on two-dimensional interpolation, which is characterized in that the channel rough estimate
Module is further used for according to the frequency pilot sign being inserted into the originally transmitted signal, using channel estimation methods to receiving end
The received originally transmitted signal pilot point carry out channel estimation, obtain channel estimation value；
Wherein, the channel estimation methods include least squares estimate, the linear minimum respectively estimation technique, maximum likelihood estimate
Or Bayes' assessment.
8. the channel estimation system according to claim 5 based on two-dimensional interpolation, which is characterized in that the pilot tone divides single
Diamond shape pilot tone plane is divided into the first sub- pilot tone plane of the rectangular mesh shape of rule and the mistake of the second sub- pilot tone plane by member
Journey includes:
The odd-numbered line and even number line where the cell particular interference signal in diamond shape pilot tone plane are extracted respectively, composition rule
Equally distributed first sub- pilot tone and the second sub- pilot tone；
Odd-numbered line where the cell particular interference signal of the first sub- pilot tone in diamond shape pilot tone is retained and removes even number line and is done
Signal is disturbed, the first sub- pilot tone plane of rectangular mesh shape is constituted；
Even number line where the cell particular interference signal of the second sub- pilot tone in diamond shape pilot tone is retained and removes odd-numbered line and is done
Signal is disturbed, the second sub- pilot tone plane of rectangular mesh shape is constituted.
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