CN107104916A - It is applicable the iteration related symbol timing estimation method of LTE multiple user uplinks - Google Patents

It is applicable the iteration related symbol timing estimation method of LTE multiple user uplinks Download PDF

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CN107104916A
CN107104916A CN201710166155.6A CN201710166155A CN107104916A CN 107104916 A CN107104916 A CN 107104916A CN 201710166155 A CN201710166155 A CN 201710166155A CN 107104916 A CN107104916 A CN 107104916A
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mrow
frequency
pilot tone
msup
sequence
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宫丰奎
闪硕
张航
张南
李果
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Xidian University
CETC 54 Research Institute
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CETC 54 Research Institute
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2647—Arrangements specific to the receiver only
    • H04L27/2649—Demodulators
    • H04L27/265—Fourier transform demodulators, e.g. fast Fourier transform [FFT] or discrete Fourier transform [DFT] demodulators
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2647—Arrangements specific to the receiver only
    • H04L27/2655—Synchronisation arrangements
    • H04L27/2668—Details of algorithms
    • H04L27/2669—Details of algorithms characterised by the domain of operation
    • H04L27/2672—Frequency domain
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2647—Arrangements specific to the receiver only
    • H04L27/2655—Synchronisation arrangements
    • H04L27/2668—Details of algorithms
    • H04L27/2673—Details of algorithms characterised by synchronisation parameters
    • H04L27/2675—Pilot or known symbols

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  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Physics & Mathematics (AREA)
  • Discrete Mathematics (AREA)
  • General Physics & Mathematics (AREA)
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Abstract

The invention belongs to mobile communication technology field, a kind of iteration related symbol timing estimation method for being applicable LTE multiple user uplinks is disclosed, by removing cyclic prefix, Fast Fourier Transform (FFT), concentrate sub-carriers demapping, cyclic shift and the isolated reception pilot tone of user；Suitable reception pilot tone and its local pilot tone are determined by pilot tone selection, and it is split；By the pilot tone after segmentation, first time Timing error estimate value is calculated, and amendment pilot tone is worth to using this；Amendment pilot tone and local pilot tone are split, and calculate second of Timing error estimate value；Final Timing error estimate value is calculated according to estimate twice.The present invention compared with the first path search algorithm improves estimated accuracy, it is to avoid complex division, reduces the complexity of estimation, available for the multi-user scene under the centralized subcarrier maps of LTE up-links.

Description

It is applicable the iteration related symbol timing estimation method of LTE multiple user uplinks
Technical field
The invention belongs to mobile communication technology field, more particularly to a kind of iteration phase for being applicable LTE multiple user uplinks Close symbol timing estimation method.
Background technology
With the fast development of the communication technology, the LTE (Long Term Evolution) of 4G GSMs is used as Release 10 and its version afterwards reach its maturity.LTE up-links have support high speed data transfer, spectral efficient, Many advantages, such as high mobility, this mainly has benefited from LTE up-links using single-carrier frequency division multiple access SC-FDMA (Single Carrier Frequency Division Multiple-Access) technology.The technology is in satellite communication, communication between devices etc. It is obtained for and is widely applied in scene.SC-FDMA has the features such as peak-to-average force ratio is low, the availability of frequency spectrum is high, anti-fading ability is strong, But in the multi-user case, the transmission signal of each user is superimposed in receiving terminal base station, timing offset between base station and user and Orthogonality between frequency deviation meeting joint effect subcarrier, causes inter-user interference.Timing error can also cause intersymbol interference simultaneously, enter And influence systematic function.So, it is necessary to which the Symbol Timing estimation that a kind of complexity is low, precision is high is calculated in LTE up-links Method.Domestic and foreign scholars propose the algorithm of many relevant Symbol Timings estimations, such as Niyazi Odabasioglu in 2015 et al. Published thesis in IEEE Application of Information and Communication Technologies “Cyclic Prefix Based Time Synchronization and Comb Type Channel Estimation For SC-FDMA Systems over Time-Varying Channels ", the paper proposes the maximum based on cyclic prefix Possibility predication algorithm carries out Symbol Timing estimation, but the algorithm, under multi-user scene, implementation complexity is very high, and many Under the channel of footpath, cyclic prefix can be by multi-path jamming.The traditional method of another kind of comparison is accorded with using channel impulse response Number timing estimation.As N Chen in 2003 et al. publish thesis in IEEE Vehicular Technology Conference " OFDM timing synchronization under multi-path channels " are utilized the paper proposes one kind The method that channel impulse response carries out the first path search, it is adaptable to SC-FDMA multi-user scenes, but this kind of algorithm will use plural number Division arithmetic, algorithm complex is higher, and evaluated error is larger under multi-user.In order to lift estimation accuracy, many scholars All conduct in-depth research.Hao Zhou in 2009 et al. are delivered in IEEE Transactions on Broadcasting Paper " A Maximum Likelihood Fine Timing Estimation for Wireless OFDM Systems ", The paper is based on channel impulse response, it is proposed that a kind of method that maximal possibility estimation is carried out using channel autocorrelation matrix, its Estimation accuracy is enhanced compared with the first path search algorithm, but the algorithm default channel statistical information is known, it is necessary to multiple Miscellaneous matrix operation, and complexity can increase with the increase of maximum timing offset., J.A.Peral-Rosado et al. in 2014 Published thesis " Joint maximum in EURASIP Journal on Advances in Signal Processing Likelihood time-delay estimation for LTE positioning in multipath channels ", The paper proposes the hybrid estimation model of a kind of combination tap and any tap at equal intervals, and maximal possibility estimation is utilized to carry out Timing estimation, accuracy of estimation and precision are all enhanced compared with the first path search algorithm, but require very high to complexity. The conventional method of an also class is the correlation estimation symbol timing error using synchronous signaling or frequency pilot sign.Led in traditional In frequency correlation technique, adjacent frequency pilot sign has special design in structure and content, and receiver can be special using its Property is timed the estimation of error.But design of this kind of method to pilot tone is required, and it is possible to estimation range occur smaller The problem of.As Pramod Udupa in 2013 et al. publish thesis in IEEE Vehicular Technology Conference “A Novel Hierarchical Low Complexity Synchronization Method for OFDM Systems”.The paper proposes a kind of new pilot tone related symbol timing estimation method, but it is special to being designed with for pilot tone It is required that, it is not suitable for LTE up-links.Analyzed based on more than, it is necessary to a kind of complicated in LTE uplink SC-FDMA systems Degree is low, and precision is high, it is adaptable to the symbol timing estimation method of multiuser asynchronous scene.
In summary, the problem of prior art is present be：Traditional timing estimation method is in the multiuser asynchronous scene of multicarrier Lower complexity is high, and estimated accuracy is low.
The content of the invention
The problem of existing for prior art, the invention provides a kind of iteration phase for being applicable LTE multiple user uplinks Close symbol timing estimation method.
The present invention is achieved in that a kind of iteration related symbol timing estimation side for being applicable LTE multiple user uplinks Method, the iteration related symbol timing estimation method for being applicable LTE multiple user uplinks is by removing cyclic prefix, quick Fu In leaf transformation, concentrate sub-carriers demapping, cyclic shift and the isolated reception pilot tone of user；It is true by pilot tone selection Fixed suitable reception pilot tone and its local pilot tone, and it is split；By the pilot tone after segmentation, timing for the first time is calculated by mistake Poor estimate, and it is worth to amendment pilot tone using this；Amendment pilot tone and local pilot tone are split, and calculate second of timing Error estimate；Final Timing error estimate value is calculated according to estimate twice.
Further, the iteration related symbol timing estimation method for being applicable LTE multiple user uplinks includes following step Suddenly：
1) in each subframe of each frame data of receiving terminal, r is usediRepresent i-th of time domain pilot with cyclic prefix Sequence, wherein i=1,2, remove its cyclic prefixObtain time domain pilot sequenceShouldIt is a N point sequence；
N=128,256,512,1024,1536,2048；
2) to time domain pilot sequenceFast Fourier Transform (FFT) FFT is carried out, N point frequency-domain pilot sequences R is obtainedi, and to RiEnter Row M/2 dot cycles displacement obtains pilot tone shift sequence Fi, then to the FiProgress is concentrated sub-carriers demapping to obtain M points and connect Receive frequency-domain pilot sequence Si, wherein M corresponds to N, M=72,180,300,600,900,1200；
3) M points are received into frequency-domain pilot sequence SiSplit according to the method for salary distribution of each user, extraction user l is corresponding to be connect Receive frequency-domain pilot sequenceAnd extracted in receiving terminalCorresponding local frequency-domain pilot sequenceWherein m=0,1 ... Nl- 1, Subscript l=1,2 ... U are Customs Assigned Number, and U is number of users, user l reception frequency-domain pilot sequence and local pilot tone sequence Row contain NlIt is individual, wherein Nl=12 λl, 12 be the number of subcarriers contained by a resource block, λlShared by user l Resource block quantity；
4) utilize and receive frequency-domain pilot sequenceThe secondary power of the norm of channel two at each frequency-domain pilot sequence of calculating user l
5) secondary power of the norm of channel two is obtainedMaximum corresponding pilot tone numbering According to energy measuring principle, i is taken outmaxCorresponding reception frequency-domain pilot sequenceLed with local frequency domain Frequency sequence
6) willWithBe divided into that length is p respectively some sections, by the phase of the reception frequency-domain pilot sequence of segmentation Adjacent two segment tables are shown as SaAnd S (k)a+1(k+p) adjacent two segment table of the local frequency-domain pilot sequence of segmentation, is shown as CaAnd C (k)a+1 (k+p), whereinτmaxFor the maximum symbol timing error of system, a=0,1,2 ..., d1- 2, d1=Nl/ p, ap≤k ≤(a+1)·p-1；
7) according to the S 6) obtaineda(k)、Sa+1(k+p)、Ca(k)、Ca+1(k+p), calculateWithSegmentation correlation αa：
Wherein subscript * represents conjugate transposition；
Antitrigonometric function is recycled to obtain αaCorresponding angle ∠ αa=angle (αa)；
8) according to ∠ αaCalculate each segmentation correlation αaCorresponding timing estimation value：To the τaAsk calculation Number average value simultaneously rounds up, and obtains the estimate of first time symbol timing errorWhereinTable Show and round downwards；
9) according to estimate τ1With 2) in centralized subcarrier maps mode structuring user's l NlRepair Positive diagonal matrix Λl：
And diagonal matrix Λ is corrected in utilizationlCalculate and receive pilot tone Orders Corrected：
10) pilot tone Orders Corrected will be receivedWith local frequency-domain pilot sequenceIt is q to be divided into length respectively Some sections, be expressed as Y by adjacent two of the reception pilot tone Orders Corrected of segmentationbAnd Y (t)b+1(t+q), by segmentation Adjacent two of local frequency-domain pilot sequence are expressed as CbAnd C (t)b+1(t+q), wherein q ＞ p, b=0,1,2 ..., d2- 2, d2= Nl/ q, bq≤t≤(b+1) q-1；
11) according to the Y 10) obtainedb(t)、Yb+1(t+q)、Cb(t)、Cb+1(t+q), calculateWithSegmentation it is related Value βb：
Wherein subscript * represents conjugate transposition；
Antitrigonometric function is recycled to obtain βbCorresponding angle ∠ βb=angle (βb)；
12) according to ∠ βbCalculate each segmentation correlation βbCorresponding timing estimation valueTo the νbAsk calculation Number average value simultaneously rounds up, and obtains the estimate of second of symbol timing error
13) timing estimation twice more than, obtains symbol timing error estimate τ=τ of final reception subframe1+ τ2。
Further, the step 1) in i-th of time domain pilot sequence with cyclic prefixr i, it is expressed as follows：
Wherein, cyclic prefixIt is expressed as：Time domain is led Frequency sequenceIt is expressed as：
N=128,256,512,1024,1536,2048, expression subcarrier number, L=18,20, represent cyclic prefix Length, wherein subscript T represents transposition.
Further, the step 2) in Fast Fourier Transform (FFT), be expressed as follows：
Ri(n)=FFT { ri(k)}；
Wherein k=0,1 ..., N-1, n=0,1 ..., N-1；
N point frequency-domain pilot sequences Ri, it is expressed as follows：
Ri=[Ri(0),Ri(1),…,Ri(N-1)]T。
Further, the step 2) in obtained pilot tone shift sequence Fi, it is expressed as follows：
Fi=[Ri(M/2),Ri(M/2+1),…,Ri(N-1),Ri(0),Ri(1),…,Ri(M/2-1)]T；
Wherein RiValue in () bracket first increases to N-1 successively from M/2, then increases to M/2-1 successively from 0；
To pilot tone shift sequence FiCarry out concentrating sub-carriers demapping, be by by FiFormula is concentrated to carry with one Ripple demapping matrix D, which is multiplied, to be obtained：
D·Fi=Si；
Wherein Si=[Si(0),Si(1),…,Si(m),…,Si(M-1)]T, m=0,1 ..., M-1, D=[IM 0M×(N-M)], wherein ΙMExpression M is unit matrix, 0M×(N-M)Represent M × (N-M) dimension null matrix.
Further, the step 3) in the corresponding reception frequency-domain pilot sequences of user lMIt is expressed as：
Wherein m=0,1 ... Nl- 1, νl=1,2 ..., Nl, the use before Customs Assigned Number l=1,2 ... U, l ' expression user l Family, l '=1,2 ... l-1.
Further, the step 9) middle amendment diagonal matrix ΛlIn Γl(νl) represent ΓlνlIndividual element, ΓlIt is The corresponding frequency modification vectors of user l：
Γl(νl)=Γ (ν)；
Wherein νl=1,2 ... Nl,
Γ is the corresponding frequency modification vector of system bandwidth：
Γ=[Γ1,Γ2,…,ΓU]=[N-M/2, N-M/2+1 ..., N-1,0,1 ..., M/2-1],
Value in vector first increases to N-1 successively from N-M/2, then increases to M/2-1 successively from 0.
Another object of the present invention is to provide a kind of application the iteration correlative symbol for being applicable LTE multiple user uplinks The 4G GSMs of number timing estimation method.
Another object of the present invention is to provide a kind of application the iteration correlative symbol for being applicable LTE multiple user uplinks The communication system of number timing estimation method.
Advantages of the present invention and good effect are：By being applicable to multiuser asynchronous feelings to pilot tone progress processing in frequency domain Condition；The present invention, without particular/special requirement, can support the pilot frequency sequence of different length to the design of pilot tone；By flexibly changing related operation Points, the estimation range of the related timing estimation algorithms of pilot tone is increased, so that the related timing estimation side of traditional pilot tone Method goes for LTE up-links；By iteration related operation, timing estimation value is estimated twice, estimation is improved Precision；The secondary power that the norm of pilot tone two is received by calculating carries out energy measuring, so as to select leading for channel status desired positions Frequency does timing estimation, relative to the mode that other pilot tone related algorithms carry out equal proportion merging to multiple pilot tone estimated results, Computation complexity is reduced, performance is also improved；The present invention, which returns to time domain after first time is estimated, not and is timed, to be estimated to mend Repay, but construction amendment diagonal matrix is compensated, so as to avoid a Fourier transformation, is not reducing the feelings of estimation performance Under condition, the complexity of iteration is greatly reduced.
Simulation result shows that the present invention improves the scope and performance of timing estimation under relatively low complexity, meets LTE The requirement of standard.
Brief description of the drawings
Fig. 1 is the iteration related symbol timing estimation side provided in an embodiment of the present invention for being applicable LTE multiple user uplinks Method flow chart.
Fig. 2 is the iteration related symbol timing estimation side provided in an embodiment of the present invention for being applicable LTE multiple user uplinks The implementation process figure of method.
Fig. 3 is the subframe structure schematic diagram provided in an embodiment of the present invention for emulating and using under 3MHz bandwidth, 2 pilot tones.
Fig. 4 is concentration sub-carriers demapping provided in an embodiment of the present invention and cyclic shift schematic diagram.
Fig. 5 is provided in an embodiment of the present invention to receiving frequency-domain pilot sequenceWith local frequency-domain pilot sequenceCarry out The schematic diagram of segmentation.
Fig. 6 is frame structure shown in utilization Fig. 3 provided in an embodiment of the present invention, and the estimation emulated in the case where signal to noise ratio is 10dB is missed Poor block diagram.
Fig. 7 is frame structure shown in utilization Fig. 3 provided in an embodiment of the present invention, and the estimation emulated in the case where signal to noise ratio is 0dB is missed Poor block diagram.
Embodiment
In order to make the purpose , technical scheme and advantage of the present invention be clearer, with reference to embodiments, to the present invention It is further elaborated.It should be appreciated that the specific embodiments described herein are merely illustrative of the present invention, it is not used to Limit the present invention.
The application principle of the present invention is explained in detail below in conjunction with the accompanying drawings.
As shown in figure 1, the iteration related symbol timing provided in an embodiment of the present invention for being applicable LTE multiple user uplinks is estimated Meter method comprises the following steps：
S101：By removing cyclic prefix, sub-carriers demapping, cyclic shift and use are concentrated in Fast Fourier Transform (FFT) The isolated reception pilot tone in family；
S102：Suitable reception pilot tone and its local pilot tone are determined by pilot tone selection, and it is split；
S103：By the pilot tone after segmentation, first time Timing error estimate value is calculated, and amendment is worth to using this and is led Frequently；
S104：Amendment pilot tone and local pilot tone are split, and calculate second of Timing error estimate value；
S105：Final Timing error estimate value is calculated according to estimate twice.
The application principle of the present invention is further described below in conjunction with the accompanying drawings.
Reference picture 2, implementation steps of the invention are as follows：
Step 1. removes cyclic prefix.
1a) in each subframe of each frame data of receiving terminal, r is usediRepresent i-th of time domain pilot with cyclic prefix Sequence：
Wherein：For cyclic prefix, i=1,2；
For time domain pilot sequence, N=128,256,512,1024,1536, 2048；
1b) remove cyclic prefixObtain time domain pilot sequence
Reference picture 3, the present invention is by taking 2 pilot tone SC-FDMA subframes under LTE up-link 3MHz bandwidth as an example, and number of users is 3, takes N =256, L=18, i=1,2；To the time domain pilot sequence r with cyclic prefix1, remove the cyclic prefix that length is 18Obtain 256 time domain pilot sequencesWherein, To the time domain pilot sequence r with cyclic prefix2, remove the cyclic prefix that length is 18Obtain 256 time domain pilot sequencesWherein,
Step 2. Fast Fourier Transform (FFT), cyclic shift, concentration sub-carriers demapping.
Reference picture 4, this step is implemented as follows：
2a) to time domain pilot sequenceFast Fourier Transform (FFT) FFT is carried out, N point frequency-domain pilot sequences R is obtainedi：
Ri=[Ri(0),Ri(1),…,Ri(N-1)]T；
To the RiCarry out M/2 dot cycles displacement and obtain pilot tone shift sequence Fi, then to the FiCarry out concentration sub-carriers Demapping obtains M points and receives frequency-domain pilot sequence Si, wherein, the formula of Fast Fourier Transform (FFT) is expressed as Ri(n)=FFT { ri (k) }, pilot tone shift sequence FiIt is expressed as：
Fi=[Ri(M/2),Ri(M/2+1),…,Ri(N-1),Ri(0),Ri(1),…,Ri(M/2-1)]T；
M=72,180,300,600,900,1200, m=0,1 ..., M-1, RiValue in () bracket first from M/2 successively N-1 is increased to, then M/2-1 is increased to successively from 0；Sub-carriers demapping is concentrated, is by by FiFormula is concentrated to carry with one Ripple demapping matrix D, which is multiplied, to be obtained：
D·Fi=Si；
Wherein Si=[Si(0),Si(1),…,Si(m),…,Si(M-1)]T, m=0,1 ..., M-1, D=[IM 0M×(N-M)], wherein ΙMExpression M is unit matrix, 0M×(N-M)Represent M × (N-M) dimension null matrix；
Fast Fourier Transform (FFT), cyclic shift, subcarrier demapping 2b) are carried out to 3 user's pilot tones.
2b1) in this example, N=256, M=180, after Fast Fourier Transform (FFT), two frequency-domain pilot sequences distinguish table It is shown as：
R1=[R1(0),R1(1),…,R1(255)]T, R2=[R2(0),R2(1),…,R2(255)]T；
2b2) for two frequency-domain pilot sequence R1,R2, 180/2=90 dot cycles displacement is carried out respectively obtains two frequency domains Pilot shift sequence F1,F2；
2b3) respectively to F1,F2Carry out concentrating sub-carriers demapping, obtain 180 points of two reception frequency-domain pilot sequences S1、S2, wherein, first cyclically shifted sequences F1With second cyclically shifted sequences F2It is expressed as：
F1=[R1(90),…,R1(255),R1(0),…,R1(89)]T；
F2=[R2(90),…,R2(255),R2(0),…,R2(89)]T；
RiValue in () bracket first increases to 255 successively from 90, then increases to 89 successively from 0；Concentrate sub-carriers solution Mapping matrix D is expressed as D=[I180 0180×76]；
Two 180 points receive frequency-domain pilot sequence and are expressed as：
S1=[S1(0),S1(2)…,S1(178),S1(179)]T；
S2=[S2(0),S2(2)…,S2(178),S2(179)]T。
Step 3. user separates.
M points 3a) are received into frequency-domain pilot sequence SiSplit according to the method for salary distribution of each user, extract user l corresponding Receive frequency-domain pilot sequenceAnd extracted in receiving terminalCorresponding local frequency-domain pilot sequenceWherein m=0,1 ... Nl- 1, subscript l=1,2 ... U are Customs Assigned Number, and U is number of users, user l reception frequency-domain pilot sequence and local pilot tone Sequence contains NlIt is individual, wherein Nl=12 λl, 12 be the number of subcarriers contained by a resource block, λlShared by user l Resource block quantity, the corresponding reception frequency-domain pilot sequences of user lMIt is expressed as：
Wherein m=0,1 ... Nl- 1, νl=1,2 ..., Nl, the use before Customs Assigned Number l=1,2 ... U, l ' expression user l Family, l '=1,2 ... l-1；
3b) take out user's pilot tone under 3 users：
In this example, N1=N2=N3=60, be 12 integral multiple, M=180, two 180 points obtained to step 2 Receive frequency-domain pilot sequence S1、S2Split according to the method for salary distribution of each user, respectively obtain the frequency-domain pilot sequence of user 1：
The frequency-domain pilot sequence of user 2：
The frequency-domain pilot sequence of user 3：
Step 4. calculates the secondary power of the norm of channel two at each pilot tones of user l, it is determined that the reception frequency domain to be used is led Frequency sequence and local frequency-domain pilot sequence.
4a) utilize and receive frequency-domain pilot sequenceThe norm of channel two is secondary at each frequency-domain pilot sequence of calculating user l Power：
Obtain the secondary power of the norm of channel twoMaximum corresponding pilot tone numberingAccording to energy measuring principle, i is taken outmaxCorresponding reception frequency-domain pilot sequenceWith local frequency Domain pilot frequency sequence
Secondary power 4b) is calculated, according to energy measuring principle, suitable pilot frequency sequence is selected：
In this example, by taking user 1 as an example.
First reception frequency-domain pilot sequence of user 1The secondary power of the corresponding norm of channel two is expressed asSecond reception frequency-domain pilot sequence of user 1The two of the corresponding norm of channel two Power is expressed as
ObtainWithIn maximum corresponding pilot tone numberingAssuming that calculating Obtain imax=2, the then imaxCorrespondenceTake outCorresponding reception frequency-domain pilot sequenceWith local pilot tone sequence Row
Step 5. pair receives frequency-domain pilot sequenceWith local frequency-domain pilot sequenceSplit.
Reference picture 5, this step is implemented as follows：
5a) the reception frequency-domain pilot sequence for obtaining step 4With local frequency-domain pilot sequenceSegmentation growth respectively Degree is some sections of p, and adjacent two segment table of the reception frequency-domain pilot sequence of segmentation is shown as into SaAnd S (k)a+1(k+p), it will divide Adjacent two segment table for the local frequency-domain pilot sequence cut is shown as CaAnd C (k)a+1(k+p), whereinτmaxFor system most Big timing error, a=0,1,2 ..., d1- 2, d1=M/p, ap≤k≤(a+1) p-1；
5b) two pilot frequency sequences of taking-up are split.
In this example, it is assumed that τmax=8, step 4 is obtainedWithIf it is p=12's to be divided into length respectively Dry section, S is shown as by adjacent two segment table of the reception frequency-domain pilot sequence of segmentationaAnd S (k)a+1(k+12)；By the local frequency of segmentation Adjacent two segment table of domain pilot frequency sequence is shown as CaAnd C (k)a+1(k+12), whereind1=M/p=15, A=0,1,2 ..., 13, a12≤k≤(a+1) 12-1.
Step 6. calculates correlation αaAnd its corresponding angle ∠ αa。
6a) the S obtained according to step 5a(k)、Sa+1(k+p)、Ca(k)、Ca+1(k+p), calculate and receive frequency-domain pilot sequenceWith local frequency-domain pilot sequenceSegmentation correlation αa：
Wherein subscript * represents conjugate transposition；
6b) α is obtained using antitrigonometric functionaCorresponding angle ∠ αa=angle (αa)。
In this example, imax=2, l=1, the S obtained according to step 5a(k)、Sa+1(k+12)、Ca(k)、Ca+1(k+12), Calculate and receive frequency-domain pilot sequenceWith local frequency-domain pilot sequenceSegmentation correlation α0,α1,…,αa,…,α13：
Antitrigonometric function is recycled to obtain α respectively0,α1,...,α13Corresponding angle ∠ α0,∠α1,…,∠α13。
Step 7. calculates the estimate τ of first time timing error1。
According to ∠ αaCalculate each segmentation correlation αaCorresponding timing estimation value：To the τaAsk and count Average value simultaneously rounds up, and obtains the estimate of first time timing errorWhereinRepresent downward Round.
In this example, according to ∠ α0,∠α1,…,∠αa,…,∠α13Calculate each segmentation correlation α0,α1,…, αa,…,α13Corresponding timing estimation value τ0,τ1,…,τa,…,τ13：
To τ0,τ1,…,τa,…,τ13Seek arithmetic average and round up, obtain the estimate of first time timing error：
Step 8. construction amendment diagonal matrix simultaneously calculates reception pilot tone Orders Corrected.
8a) according to estimate τ1With the N of the centralized subcarrier maps mode structuring user's l in step 2lMaintenance is just diagonal Matrix Λl：
Wherein Γl(νl) represent ΓlνlIndividual element, Γl(νl)=Γ (ν), νl=1,2 ... Nl, The corresponding frequency modification vector Γ of system bandwidth is expressed as：
Γ=[Γ1,Γ2,…,ΓU]=[N-M/2, N-M/2+1 ..., N-1,0,1 ..., M/2-1]；
Its value first increases to N-1 successively from N-M/2, then increases to M/2-1 successively from 0；
8b) utilize and correct diagonal matrix ΛlCalculate and receive pilot tone Orders Corrected
L=1, is modified to the reception pilot tone of user 1, according to the subcarrier maps in step 2 in this example Mode constructs 60 maintenance Positive diagonal matrix Λ1For：
I in this examplemax=2, l=1, therefore receive frequency-domain pilot sequenceIt is expressed asIt is diagonal using the amendment Matrix ΛlCalculate and receive pilot tone Orders Corrected
Step 9. pair receives pilot tone Orders CorrectedWith local frequency-domain pilot sequenceSplit.
It will 9a) receive pilot tone Orders CorrectedWith local frequency-domain pilot sequenceIt is q to be divided into length respectively Some sections；
9b) Y is expressed as by adjacent two of the reception pilot tone Orders Corrected after segmentationbAnd Y (t)b+1(t+q), it will divide Adjacent two of the local frequency-domain pilot sequence cut are expressed as CbAnd C (t)b+1(t+q), wherein q ＞ p, b=0,1,2 ..., d2- 2, d2=M/q, bq≤t≤(b+1) q-1.
In this example, imax=2, l=1, will receive pilot tone Orders CorrectedWith local frequency-domain pilot sequence Be divided into that length is q=30 respectively some sections, adjacent two of the reception pilot tone Orders Corrected of segmentation are expressed as YbAnd Y (t)b+1(t+30), it is expressed as C by adjacent two of the local frequency-domain pilot sequence of segmentationbAnd C (t)b+1(t+30), wherein Q ＞ p, d2=M/q=6, b=0,1,2 ..., 4, b30≤t≤(b+1) 30-1.
Step 10. calculates correlation βbAnd its corresponding angle ∠ βb。
10a) the Y obtained according to step 9b(t)、Yb+1(t+q)、Cb(t)、Cb+1(t+q), calculate and receive pilot tone amendment SequenceWith local frequency-domain pilot sequenceSegmentation correlation βb：
Wherein subscript * represents conjugate transposition；
10b) β is obtained using antitrigonometric functionbCorresponding angle ∠ βb=angle (βb)。
In this example, the Y obtained according to step 9b(t)、Yb+1(t+30)、Cb(t)、Cb+1(t+30), calculate and receive frequency domain Pilot tone Orders CorrectedWith local frequency-domain pilot sequenceSegmentation correlation β0, β1,…,βb,…,β4：
Antitrigonometric function is recycled to obtain β0, β1,…,β4Corresponding angle ∠ β0,∠β1,…,∠β4。
Step 11. calculates the estimate τ of second of timing error2。
According to ∠ βbCalculate each segmentation correlation βbCorresponding timing estimation valueTo the νbAsk and count Average value simultaneously rounds up, and obtains the estimate of second of timing error
In this example, according to ∠ β0,∠β1,…,∠βb,…,∠β4Calculate each segmentation correlation β0,β1,…, βb,…,β4Corresponding timing estimation value ν0,ν1,…,νb,…ν4：
To ν0,ν1,…,νb,…ν4Seek arithmetic average and round up, obtain the estimate of second of timing error
Step 12. calculates the estimate τ of final timing error.
The timing estimation twice more than, obtains symbol timing error estimate τ=τ of final reception subframe1+τ2。
The application effect of the present invention is explained in detail with reference to emulation.
Simulated conditions：In LTE standard uplink SC-FDMA system, by taking 3MHz bandwidth as an example, number of users is 3, test Data are 100000 frames, the first path search of contrast and method performance proposed by the invention.
1st, emulation content and result：
Emulation 1, be in 3 users, with a width of 3MHz, signal to noise ratio with existing first path search algorithm with the method for the present invention Evaluated error is emulated under the conditions of 10dB, as a result as shown in Figure 6.Inventive algorithm and the first footpath are searched according to simulation result Rope algorithm carries out statistical analysis, and the ratio that frame number of two kinds of algorithms when evaluated error is 0 accounts for totalframes is respectively 37% He 19%, the ratio that the frame number when evaluated error is (- 1 ,+1) accounts for totalframes is respectively 94% and 79%.Therefore, the present invention is calculated 18% and 15% has been respectively increased when evaluated error is 0 and (- 1 ,+1) relative to the first path search algorithm in method.
Emulation 2, be in 3 users, with a width of 3MHz, signal to noise ratio with existing first path search algorithm with the method for the present invention Evaluated error is emulated under conditions of 0dB, as a result as shown in Figure 7.According to simulation result to inventive algorithm and the first footpath Searching algorithm carries out statistical analysis, and the ratio that frame number of two kinds of algorithms when evaluated error is 0 accounts for totalframes is respectively 31% He 10%, the ratio that the frame number when evaluated error is (- 1 ,+1) accounts for totalframes is respectively 76% and 38%, evaluated error for (- 10 ,+10) when frame number to account for the ratio of totalframes be respectively 99% and 61%.Therefore, inventive algorithm is relative to the first path search Algorithm has been respectively increased 21%, 38%, 38% when evaluated error is 0, (- 1 ,+1) and (- 10 ,+10).
From Fig. 6 and Fig. 7, under 0dB and 10dB relatively low signal-to-noise ratio, the present invention is better than the first path search in performance Algorithm.Although the present invention introduces 2 times and asks phase angle computing, complex division in the first path search algorithm is avoided and substantial amounts of Complex multiplication, complexity is relatively low.
The foregoing is merely illustrative of the preferred embodiments of the present invention, is not intended to limit the invention, all essences in the present invention Any modifications, equivalent substitutions and improvements made within refreshing and principle etc., should be included in the scope of the protection.

Claims (9)

1. a kind of iteration related symbol timing estimation method for being applicable LTE multiple user uplinks, it is characterised in that described to be applicable The iteration related symbol timing estimation method of LTE multiple user uplinks is by removing cyclic prefix, Fast Fourier Transform (FFT), collection Middle sub-carriers demapping, cyclic shift and the isolated reception pilot tone of user；Determine suitably to connect by pilot tone selection Pilot tone and its local pilot tone are received, and it is split；By the pilot tone after segmentation, first time Timing error estimate value is calculated, And it is worth to amendment pilot tone using this；Amendment pilot tone and local pilot tone are split, and calculate second of Timing error estimate Value；Final Timing error estimate value is calculated according to estimate twice.
2. the iteration related symbol timing estimation method as claimed in claim 1 for being applicable LTE multiple user uplinks, its feature It is, the iteration related symbol timing estimation method for being applicable LTE multiple user uplinks comprises the following steps：
1) in each subframe of each frame data of receiving terminal, r is usediI-th of time domain pilot sequence with cyclic prefix is represented, Wherein i=1,2, remove its cyclic prefixObtain time domain pilot sequenceShouldIt is a N point sequence；
N=128,256,512,1024,1536,2048；
2) to time domain pilot sequenceFast Fourier Transform (FFT) FFT is carried out, N point frequency-domain pilot sequences R is obtainedi, and to RiCarry out M/ 2 dot cycles displacement obtains pilot tone shift sequence Fi, then to the FiCarry out concentrating sub-carriers demapping to obtain M points reception frequency Domain pilot frequency sequence Si, wherein M corresponds to N, M=72,180,300,600,900,1200；
3) M points are received into frequency-domain pilot sequence SiSplit according to the method for salary distribution of each user, extract the corresponding reception frequencies of user l Domain pilot frequency sequenceAnd extracted in receiving terminalCorresponding local frequency-domain pilot sequenceWherein m=0,1 ... Nl- 1, subscript l =1,2 ... U are Customs Assigned Number, and U is number of users, and user l reception frequency-domain pilot sequence and local frequency-domain pilot sequence contain There is NlIt is individual, wherein Nl=12 λl, 12 be the number of subcarriers contained by a resource block, λlFor the resource shared by user l Number of blocks；
4) utilize and receive frequency-domain pilot sequenceThe secondary power of the norm of channel two at each frequency-domain pilot sequence of calculating user l
5) secondary power of the norm of channel two is obtainedMaximum corresponding pilot tone numbering According to energy measuring principle, i is taken outmaxCorresponding reception frequency-domain pilot sequenceLed with local frequency domain Frequency sequence
6) willWithBe divided into that length is p respectively some sections, by adjacent the two of the reception frequency-domain pilot sequence of segmentation Segment table is shown as SaAnd S (k)a+1(k+p) adjacent two segment table of the local frequency-domain pilot sequence of segmentation, is shown as CaAnd C (k)a+1(k+ P), whereinτmaxFor the maximum symbol timing error of system, a=0,1,2 ..., d1- 2, d1=Nl/ p, ap≤k≤ (a+1)·p-1；
7) according to the S 6) obtaineda(k)、Sa+1(k+p)、Ca(k)、Ca+1(k+p), calculateWithSegmentation correlation αa：
Wherein subscript * represents conjugate transposition；
Antitrigonometric function is recycled to obtain αaCorresponding angle ∠ αa=angle (αa)；
8) according to ∠ αaCalculate each segmentation correlation αaCorresponding timing estimation value：To the τaAsk count it is flat Average simultaneously rounds up, and obtains the estimate of first time symbol timing errorWhereinRepresent to Under round；
9) according to estimate τ1With 2) in centralized subcarrier maps mode structuring user's l NlRepair Positive diagonal matrix Λl：
<mrow> <msub> <mi>&amp;Lambda;</mi> <mi>l</mi> </msub> <mo>=</mo> <mi>d</mi> <mi>i</mi> <mi>a</mi> <mi>g</mi> <mrow> <mo>(</mo> <msup> <mi>e</mi> <mrow> <mo>-</mo> <mi>j</mi> <mn>2</mn> <mi>&amp;pi;</mi> <mo>&amp;CenterDot;</mo> <msub> <mi>&amp;Gamma;</mi> <mi>l</mi> </msub> <mrow> <mo>(</mo> <mn>1</mn> <mo>)</mo> </mrow> <mo>&amp;CenterDot;</mo> <msup> <mi>&amp;tau;</mi> <mn>1</mn> </msup> <mo>/</mo> <mi>N</mi> </mrow> </msup> <mo>,</mo> <msup> <mi>e</mi> <mrow> <mo>-</mo> <mi>j</mi> <mn>2</mn> <mi>&amp;pi;</mi> <mo>&amp;CenterDot;</mo> <msub> <mi>&amp;Gamma;</mi> <mi>l</mi> </msub> <mrow> <mo>(</mo> <mn>2</mn> <mo>)</mo> </mrow> <mo>&amp;CenterDot;</mo> <msup> <mi>&amp;tau;</mi> <mn>1</mn> </msup> <mo>/</mo> <mi>N</mi> </mrow> </msup> <mo>,</mo> <mo>...</mo> <mo>,</mo> <msup> <mi>e</mi> <mrow> <mo>-</mo> <mi>j</mi> <mn>2</mn> <mi>&amp;pi;</mi> <mo>&amp;CenterDot;</mo> <msub> <mi>&amp;Gamma;</mi> <mi>l</mi> </msub> <mrow> <mo>(</mo> <msub> <mi>N</mi> <mi>l</mi> </msub> <mo>)</mo> </mrow> <mo>&amp;CenterDot;</mo> <msup> <mi>&amp;tau;</mi> <mn>1</mn> </msup> <mo>/</mo> <mi>N</mi> </mrow> </msup> <mo>)</mo> </mrow> <mo>;</mo> </mrow>
And diagonal matrix Λ is corrected in utilizationlCalculate and receive pilot tone Orders Corrected：
10) pilot tone Orders Corrected will be receivedWith local frequency-domain pilot sequenceIf it is q's to be divided into length respectively Dry section, Y is expressed as by adjacent two of the reception pilot tone Orders Corrected of segmentationbAnd Y (t)b+1(t+q), by the local of segmentation Adjacent two of frequency-domain pilot sequence are expressed as CbAnd C (t)b+1(t+q), wherein q ＞ p, b=0,1,2 ..., d2- 2, d2=Nl/ Q, bq≤t≤(b+1) q-1；
11) according to the Y 10) obtainedb(t)、Yb+1(t+q)、Cb(t)、Cb+1(t+q), calculateWithSegmentation correlation βb：
Wherein subscript * represents conjugate transposition；
Antitrigonometric function is recycled to obtain βbCorresponding angle ∠ βb=angle (βb)；
12) according to ∠ βbCalculate each segmentation correlation βbCorresponding timing estimation valueTo the νbAsk count it is flat Average simultaneously rounds up, and obtains the estimate of second of symbol timing error
13) timing estimation twice more than, obtains symbol timing error estimate τ=τ of final reception subframe1+τ2。
3. the iteration related symbol timing estimation method as claimed in claim 2 for being applicable LTE multiple user uplinks, its feature Be, the step 1) in i-th of time domain pilot sequence r with cyclic prefixi, it is expressed as follows：
<mrow> <msup> <mi>r</mi> <mi>i</mi> </msup> <mo>=</mo> <msup> <mrow> <mo>&amp;lsqb;</mo> <mrow> <msubsup> <mi>r</mi> <mrow> <mi>C</mi> <mi>P</mi> </mrow> <mi>i</mi> </msubsup> <mo>,</mo> <msubsup> <mi>r</mi> <mi>p</mi> <mi>i</mi> </msubsup> </mrow> <mo>&amp;rsqb;</mo> </mrow> <mi>T</mi> </msup> <mo>;</mo> </mrow>
Wherein, cyclic prefixIt is expressed as：Time domain pilot sequenceIt is expressed as：
N=128,256,512,1024,1536,2048, expression subcarrier number, L=18,20, the length of cyclic prefix is represented, Wherein subscript T represents transposition.
4. the iteration related symbol timing estimation method as claimed in claim 2 for being applicable LTE multiple user uplinks, its feature Be, the step 2) in Fast Fourier Transform (FFT), be expressed as follows：
Ri(n)=FFT { ri(k)}；
Wherein k=0,1 ..., N-1, n=0,1 ..., N-1；
N point frequency-domain pilot sequences Ri, it is expressed as follows：
Ri=[Ri(0),Ri(1),…,Ri(N-1)]T。
5. the iteration related symbol timing estimation method as claimed in claim 2 for being applicable LTE multiple user uplinks, its feature Be, the step 2) in obtained pilot tone shift sequence Fi, it is expressed as follows：
Fi=[Ri(M/2),Ri(M/2+1),…,Ri(N-1),Ri(0),Ri(1),…,Ri(M/2-1)]T；
Wherein RiValue in () bracket first increases to N-1 successively from M/2, then increases to M/2-1 successively from 0；
To pilot tone shift sequence FiCarry out concentrating sub-carriers demapping, be by by FiWith a concentration sub-carriers solution Mapping matrix D, which is multiplied, to be obtained：
D·Fi=Si；
Wherein Si=[Si(0),Si(1),…,Si(m),…,Si(M-1)]T, m=0,1 ..., M-1, D=[IM 0M×(N-M)], wherein ΙMExpression M is unit matrix, 0M×(N-M)Represent M × (N-M) dimension null matrix.
6. the iteration related symbol timing estimation method as claimed in claim 2 for being applicable LTE multiple user uplinks, its feature Be, the step 3) in the corresponding reception frequency-domain pilot sequences of user lMIt is expressed as：
<mrow> <msubsup> <mi>S</mi> <mi>l</mi> <mi>i</mi> </msubsup> <mrow> <mo>(</mo> <mi>m</mi> <mo>)</mo> </mrow> <mo>=</mo> <msup> <mi>S</mi> <mi>i</mi> </msup> <mrow> <mo>(</mo> <msub> <mi>&amp;nu;</mi> <mi>l</mi> </msub> <mo>+</mo> <munderover> <mi>&amp;Sigma;</mi> <mrow> <msup> <mi>l</mi> <mo>&amp;prime;</mo> </msup> <mo>=</mo> <mn>1</mn> </mrow> <mrow> <mi>l</mi> <mo>-</mo> <mn>1</mn> </mrow> </munderover> <msub> <mi>N</mi> <msup> <mi>l</mi> <mo>&amp;prime;</mo> </msup> </msub> <mo>)</mo> </mrow> <mo>;</mo> </mrow>
Wherein m=0,1 ... Nl- 1, νl=1,2 ..., Nl, the user before Customs Assigned Number l=1,2 ... U, l ' expression user l, L '=1,2 ... l-1.
7. the iteration related symbol timing estimation method as claimed in claim 2 for being applicable LTE multiple user uplinks, its feature It is, the step 9) middle amendment diagonal matrix ΛlIn Γl(νl) represent ΓlνlIndividual element, ΓlIt is that user l is corresponding Frequency modification vector：
Γl(νl)=Γ (ν)；
Wherein νl=1,2 ... Nl,
Γ is the corresponding frequency modification vector of system bandwidth：
Γ=[Γ1,Γ2,…,ΓU]=[N-M/2, N-M/2+1 ..., N-1,0,1 ..., M/2-1],
Value in vector first increases to N-1 successively from N-M/2, then increases to M/2-1 successively from 0.
8. the iteration related symbol timing of LTE multiple user uplinks is applicable described in a kind of application claim 1~8 any one The 4G GSMs of method of estimation.
9. the iteration related symbol timing of LTE multiple user uplinks is applicable described in a kind of application claim 1~8 any one The communication system of method of estimation.
CN201710166155.6A 2017-03-20 2017-03-20 It is applicable the iteration related symbol timing estimation method of LTE multiple user uplinks Pending CN107104916A (en)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20120099631A1 (en) * 2009-07-03 2012-04-26 Zte Corporation Pilot-based time offset estimation apparatus and method
CN102457463A (en) * 2010-11-02 2012-05-16 中兴通讯股份有限公司 Frequency deviation estimating method and device
CN106357584A (en) * 2016-11-14 2017-01-25 西安电子科技大学 Iterative correlation symbol timing estimation method based on block-type pilot frequency

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20120099631A1 (en) * 2009-07-03 2012-04-26 Zte Corporation Pilot-based time offset estimation apparatus and method
CN102457463A (en) * 2010-11-02 2012-05-16 中兴通讯股份有限公司 Frequency deviation estimating method and device
CN106357584A (en) * 2016-11-14 2017-01-25 西安电子科技大学 Iterative correlation symbol timing estimation method based on block-type pilot frequency

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