CN105680903B - The period more pseudo-code methods of estimation of long short code direct sequency-code division multiple access signal - Google Patents
The period more pseudo-code methods of estimation of long short code direct sequency-code division multiple access signal Download PDFInfo
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
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- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/69—Spread spectrum techniques
- H04B1/707—Spread spectrum techniques using direct sequence modulation
Abstract
The present invention relates to the period more pseudo-code methods of estimation of long short code direct sequency-code division multiple access signal.Existing direct sequency-code division multiple access signal pseudo-code blind estimate technology can not be applied to spread long code scrambled period long short code direct sequency-code division multiple access signal using short code.The present invention is that long short code direct sequency-code division multiple access signal of complicated period is configured to the missing matrix model of short code direct sequency-code division multiple access signal, and compound key Matrix Estimation is modeled as blind source signal separation problem；Matrix fill-in theory is applied to compound key Matrix Estimation again, each user's compound key sequence is estimated based on singular value thresholding algorithm and fast independent component analysis algorithm；Finally utilize m-sequence displacement additivity, propose delay third-order correlation algorithm, from each user's compound key sequence estimation it includes length pseudo-code sequence.The present invention makes full use of the mathematical model of matrix fill-in and m-sequence third-order correlation peak character, realizes the blind estimate of each user's compound key sequence of signal, long scrambler sequence and short spreading code sequence successively.
Description
Technical field
The invention belongs to the blind parameter Estimation field of Direct Sequence Spread Spectrum Signal in communication countermeasure, more particularly to a kind of uses
Short code spreads more pseudo-code methods of estimation of long code scrambled period long short code direct sequency-code division multiple access signal.
Background technology
Conventional communication system mainly transmits information as much as possible using the power of limit signal and bandwidth.Spread-spectrum
Communication is the communication carried out data transmission in a bandwidth much larger than information rate, since it is not to save bandwidth as mesh
, thus different from conventional communication system.
Direct Sequence Spread Spectrum (Direct Sequence Spread Spectrum, DSSS) is the master of spread spectrum technic
Want one of mode.The core concept of direct-sequence communications system is before information code sequence is sent, with high-speed pseudo noise code to signal
It is modulated, the spread spectrum of signal, signal is made to be submerged among noise so that direct sequence signal is difficult to detect.Direct sequence signal has
There is interference rejection capability strong, be conducive to the advantages that hidden, the achievable multiple access of signal accesses, anti-fading ability is strong so that spread spectrum is logical
Letter becomes the hot topic studied at present.
CDMA (Code Division Multiple Access, CDMA) is a kind of Digital Communications With Multiple Access mode, is led to
It crosses unique code sequence and establishes channel.Direct sequency-code division multiple access (DS-CDMA) system is using DSSS technologies and CDMA technology as base
What plinth was realized.Direct sequency-code division multiple access signal can be divided into：Short code direct sequency-code division multiple access signal, long code direct sequency-code division multiple access signal and
The scrambled long short code direct sequency-code division multiple access signal of long code is spread using short code.
In communication countermeasure, the advantages that just because of the strong antijamming capability of direct sequency-code division multiple access signal, good concealment, make
Direct sequency-code division multiple access signal detection under the conditions of non-cooperative communication and blind parameter Estimation it is extremely difficult.It is pseudo- in non-cooperative communication
Random code (abbreviation pseudo-code) estimation is the premise and key of signal interception.The pseudo-code Estimation Study of short code direct sequency-code division multiple access signal
Comparative maturity, the research of long code direct sequency-code division multiple access signal also have been achieved with certain achievement.But period long short code direct expansion code
For divided into multi-address signal since its is complicated and multi-access inference, confidentiality is stronger, is brought to the pseudo-code blind estimate of non-cooperative communication
The difficulty of bigger and challenge.
Existing direct sequency-code division multiple access signal pseudo-code method of estimation is mainly decomposed by blind separation combination correlation matrix feature
Method, neural network, matching matrix and third-order correlation method are realized.Due to being included in period long short code direct sequency-code division multiple access signal
Multiple users, again comprising two pseudo-codes in each user, and correlation matrix feature decomposition method, neural network and matching matrix need
A large amount of sample of signal are wanted, can not be suitable for period long short code direct sequency-code division multiple access signal.At present about period long short code direct expansion
More pseudo-code blind estimates of CDMA signals yet there are no disclosed correlative study achievement.
Invention content
It can not blind estimate period long short code direct sequency-code division multiple access signal the purpose of the present invention is being directed in non-cooperative communication
The problem of each user's pseudo-code, proposes that a kind of long short code direct sequency-code division multiple access signal of period based on matrix fill-in and third-order correlation is more
Pseudo-code blind estimating method, so as to solve the problems, such as to be unable to estimate the period more pseudo-codes of long each user of short code direct sequency-code division multiple access signal.
The period more pseudo-code blind estimating methods of long short code direct sequency-code division multiple access signal, include the following steps in the present invention：
1st, period long short code direct sequency-code division multiple access signal is converted into baseband signal with spreading code chip polydispersity index, built
The short code direct sequency-code division multiple access signal form of equal value of period long short code direct sequency-code division multiple access signal, and establish the missing for receiving signal
Matrix model.
2nd, by carrying out matrix fill-in and singular value decomposition estimation signal compound key subspace to signal deletion matrix.
3rd, independent component analysis (Fast-ICA) estimation is carried out to signal compound key subspace and obtains each user's compound key sequence
Row.
4th, the triple correlation function of each user's compound key sequence is calculated respectively, and additivity and three rank phases are shifted according to m-sequence
Peak character is closed, estimation successively obtains each head of a household's scrambler sequence and short spreading code sequence.
The present invention makes full use of the design feature of period long short code direct sequency-code division multiple access signal, builds short code direct expansion code of equal value
Divided into multi-address signal model and blind source signal separation form realize the estimation of each user's compound key.Each user's compound key is utilized simultaneously
The displacement additivity of long scrambler m-sequence and third-order correlation peak character in sequence realize the long short code direct sequency-code division multiple access letter to the period
The estimation of number each more pseudo-codes of user.
Long scrambler and short spreading code are considered as compound key by the present invention, straight using period long short code direct sequency-code division multiple access, long code
Expand the contact of CDMA and short code direct sequency-code division multiple access, construct short code direct sequency-code division multiple access signal form of equal value and receive and believe
Number missing matrix model includes the information of each user's compound key in the missing matrix.
The present invention receives signal deletion matrix using the singular value thresholding algorithm docking in matrix fill-in theory and is filled, right
It fills obtained full matrix and carries out singular value decomposition, you can estimation obtains compound key subspace.
The compound key subspace that present invention estimation obtains not is the compound key of period long short code direct sequency-code division multiple access signal
Matrix, it belongs to same subspace with signal compound key matrix, and there are linear transformation relationships, and being realized using Fast-ICA algorithms should
The blind separation of linear model, so as to estimate to obtain each user's compound key sequence.
It, will be compound comprising long scrambler sequence and short spreading code sequence in each user's compound key sequence that present invention estimation obtains
Code sequence loops move to left several bits (identical with monocycle spread spectrum short code chip number) and are multiplied with original compound key sequence, can be with
Eliminate influence of the short spreading code to long scrambler triple correlation function.Using the displacement additivity of m-sequence and third-order correlation peak character,
Estimation obtains long scrambler sequence and short spreading code sequence successively.
The beneficial effects of the invention are as follows：
The 1st, period long short code direct sequency-code division multiple access signal is configured to the missing of multi-user's short code direct sequency-code division multiple access signal
Signal compound key Matrix Estimation is modeled as blind source signal separation problem by matrix model, can will be complicated by the modeling process
Signal model simplifies.
2nd, matrix fill-in theory is applied to signal compound key Matrix Estimation, proposes singular value thresholding algorithm and Fast-ICA
Algorithm can realize blind separation and the estimation of each user's compound key sequence.
3rd, influence of the short spreading code for long scrambler in compound key sequence is eliminated by delay multiplication, utilizes long code m-sequence
Additivity estimation long code initial phase is shifted, long scrambler sequence and short spreading code sequence can be estimated successively, and estimate performance
It greatly improves.
Specific embodiment
Illustrate the implementation steps of the present invention in detail further below.
Step 1, the more pseudo-code methods of estimation of period of the invention long short code direct sequency-code division multiple access signal when in use, will connect first
After the period long short code direct sequency-code division multiple access signal received is with spreading code chip polydispersity index, it is converted into baseband signal y (l)：
Wherein, l is sampling instant, l=0,1 ..., L-1；K is user's number；Ak、dk(l)、bk(l) and ck(l) difference table
Show spreading code that k-th of subscriber signal amplitude, information code sequence, period are G and the long scrambler that the period is N, bk(l) and ck(l) all
Using m-sequence and N ＞ ＞ G；V (l) is additive white Gaussian noise；L is signal length, and assumes L=JN, and J is positive integer；Each
With containing per familyA information symbol,It represents to take the smallest positive integral not less than x.
Signal length pseudo-code is considered as compound key, it is assumed that there are one containing same compound code sequence and information code sequence,
Spreading gain is K user's short code direct sequency-code division multiple access signal of N
Wherein,sk(n)=bk(n)ck(n) (n=0,1 ..., N-1) represents the compound key sequence of k-th of user
Row,
It is represented by the matrix form of N × M dimensions：
Wherein, S=[s1 s2 … sK], sk=[sk(0) sk(1) … sk(N-1)]T, D=[d1 d2 … dK], dk=
[dk(0) dk(1) … dk(M-1)], A=diag (A1,A2,…,AK),White Gaussian noise matrix is tieed up for N × M, S is compound
Code matrix.
According toWithCorrespondence can obtain matrixElement value with Y is respectively：
Wherein, (l)NL is represented to mould N complementation operations,Represent the maximum integer no more than x.
Obviously, signal is receivedIt isIn part sample, rest part is considered as missing.Therefore it can incite somebody to action
K user's period long short code direct sequency-code division multiple access signal modeling is the mathematical model for lacking matrix：
Wherein, Ω is the matrix of N × M dimensions, andRemaining position element is 0 (representing missing point)；⊙
Representing matrix point multiplication operation；Y isEach Lieque has lost the missing matrix of about N-G specific position element.
Signal will be received by formula (5) and (6)It is configured to the missing matrix Y of N × M dimensions.
Step 2, from the corresponding left singularity characteristics vector composition of K singular value of missing matrix Y estimation full matrix maximums
Matrix Us, utilize singular value threshold value (Singular Value Thresholding, SVT) algorithm in matrix fill-in theory
It realizes, specific method is：
1. initialize Z0∈RN×M；
2. calculate dematrix Xj=Fτ(Zj-1)；
3. by Zj=Zj-1+δ(Y-Xj⊙ Ω) update multiplier matrix Zj；
If 4.2. then j=j+1 is returned；Conversely, obtain estimated valueIt is rightInto
Row singular value decomposition can obtain compound key sequence subspace UsEstimated value
Wherein, Z0And ZjTo be respectively Iterative Matrix initial value and median, XjIteration updated value for dematrix.||Y|
|FThe Frobenius norms of representing matrix Y respectively.
Fτ(X) it is singular value threshold operator, is defined as：
Wherein, r is singular value number；λn(n=1,2, L, N) is the singular value that matrix Z is arranged in descending order, and meets λr≤τ
≤λr-1；Uz(n) and Vz(n) the n-th of the right singularity characteristics vector of the left singularity characteristics vector sum of representing matrix Z arranges respectively.
Step 3, UsThe subspace that is turned into of column vector and the subspace that is turned into of column vector of compound key matrix S belong to same
Sub-spaces, i.e., there are the relationship of linear transformation between them, using Fast-ICA algorithms, by UsThe signal that direct blind separation goes out
For Sf, to SfCarrying out symbolic operation can estimate to obtain compound key matrix, i.e.,：
The compound key matrix estimatedEach row be the corresponding compound key sequence of each user
Step 4, by the compound key of k-th of userRing shift right G bits are multiplied with former compound key, obtain
It is calculated in the range of N × NTriple correlation function
Wherein, p and q is retardation.
Due toAdditivity is then shifted according to m-sequence, can be obtained：
Wherein, ΓkFor long code m-sequence retardation.
According to m-sequence triple correlation function characteristicIt should be in coordinate points (G, Γk) at there are peak values.But by
In noise and error in numerical calculation, ΓkEstimator it is as follows：
Ring shift right ΓkBit obtains long scrambler sequence
According to the compound key sequence having been estimated thatWith long scrambler sequenceCan further it estimate
Meter obtains short spreading code sequence
By step 4, the respective long scrambler sequence of K user can be estimated according to the compound key sequence that estimation obtains respectively
Row and short spreading code sequence.
The preferred embodiment of the present invention and principle are described in detail above, to those of ordinary skill in the art
Speech, the thought provided according to the present invention will change in specific embodiment, and these changes also should be regarded as the present invention
Protection domain.
Claims (6)
1. the period more pseudo-code methods of estimation of long short code direct sequency-code division multiple access signal, it is characterised in that this method includes the following steps：
(1) period long short code direct sequency-code division multiple access signal is converted into baseband signal, structure week with spreading code chip polydispersity index
The short code direct sequency-code division multiple access signal form of equal value of phase long short code direct sequency-code division multiple access signal, and establish the missing square for receiving signal
Battle array model；
(2) by carrying out matrix fill-in and singular value decomposition estimation signal compound key subspace to signal deletion matrix；
(3) independent component analysis is carried out to signal compound key subspace to estimate to obtain each user's compound key sequence；
(4) triple correlation function of each user's compound key sequence is calculated respectively, and additivity and third-order correlation peak are shifted according to m-sequence
Characteristic, successively estimation obtain each head of a household's scrambler sequence and short spreading code sequence.
2. the more pseudo-code methods of estimation of period long short code direct sequency-code division multiple access signal as described in claim 1, it is characterised in that：Step
Suddenly the short code direct sequency-code division multiple access signal form of equal value of the long short code direct sequency-code division multiple access signal of construction schedule described in (1) refer to by
The length pseudo-code for receiving signal y (l) is considered as special compound key, and y (l) is represented by：
Wherein, l is sampling instant, l=0,1 ..., L-1；K is user's number；Ak、dk(l) k-th of subscriber signal width is represented respectively
Degree, information code sequence；sk(n)=bk(n)ck(n), n=0,1 ..., N-1 represent the compound key sequence of k-th of user, bk(n),
ck(n) spread spectrum code sequence of k-th of user, long scrambler sequence are represented respectively；X (l) represents useful signal, and v (l) is additive Gaussian
White noise；L is signal length, and assumes that L=JN, J are positive integer, 0≤j≤J；It is each to use
Contain per familyA information symbol, N and G are respectively the period of long code and short code,Representative rounds up；
It is assumed that there are one to contain same compound code sequence and information code sequence, K user's short code direct expansion code point that spreading gain is N
Multi-address signal
Wherein,
3. the more pseudo-code methods of estimation of period long short code direct sequency-code division multiple access signal as claimed in claim 2, it is characterised in that：Step
Suddenly the missing matrix model of the structure reception signal described in (1) refers to basisWithCorrespondence：
Wherein (l)NL is represented to mould N complementation operations,Represent the maximum integer no more than x；
The mathematical model that signal modeling is missing matrix will be received：
Wherein, Ω is the matrix of N × M dimensions, andRemaining position element is 0, i.e. missing point；⊙ represents square
Lattice point multiplication；Y isEach Lieque has lost the missing matrix of N-G specific position element.
4. the more pseudo-code methods of estimation of period long short code direct sequency-code division multiple access signal as claimed in claim 3, it is characterised in that：Step
Suddenly signal deletion matrix progress matrix fill-in and singular value decomposition estimation signal compound key subspace are referred to utilize described in (2)
It is more to obtain short code direct expansion code of equal value point by the long short code direct sequency-code division multiple access signal deletion matrix Y of singular value thresholding algorithm fill cycle
Location signal integrity matrixEstimated valueIt is right againSingular value decomposition is carried out, the maximum corresponding left side of K singular value is unusual
The matrix U of feature vector compositions∈RN×KAs signal compound key subspace, RN×KRepresent the real number matrix of N × K.
5. the more pseudo-code methods of estimation of period long short code direct sequency-code division multiple access signal as claimed in claim 4, it is characterised in that：Step
Suddenly (3) it is empty using independent component analysis to estimate to obtain the compound numeral of signal that each user's compound key sequence refers to that step (2) obtains
Between Us∈RN×KThe subspace that is turned into of column vector and the subspace that is turned into of column vector of signal compound key matrix S belong to same
Subspace, i.e., there are linear transformation T between them, i.e.,：
Us=TS (6)
It can be according to Fast-ICA algorithms, by U for the linear mixed modelsThe signal that direct blind separation goes out is Sf, to SfIt is accorded with
Number operation can be estimated to obtain compound key matrix, i.e.,：
The compound key matrix estimatedEach row be the corresponding compound key sequence of each user
6. the more pseudo-code methods of estimation of period long short code direct sequency-code division multiple access signal as described in claim 1, it is characterised in that：Step
Suddenly (4) estimate length pseudo-code sequence successively according to compound key sequence, and need to eliminate short spreading code by cyclic shift influences, and recycles
M-sequence displacement superimposed characteristics estimate each initial phase Γ with head of a household's scrambler sequencek, ΓkEstimator be：
WhereinIt representsTriple correlation function, p, q represent retardation；
By the compound key of k-th of userRing shift right G bits are multiplied with former compound key
Ring shift right ΓkBit obtains long scrambler sequence
According to the compound key sequence and long scrambler sequence having been estimated that, further estimation obtains short spreading code sequence
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| CN107682041B (en) * | 2017-10-19 | 2019-12-10 | 杭州电子科技大学 | Multi-antenna LC-DS-CDMA signal spreading code blind estimation method |
| CN108306655B (en) * | 2018-01-29 | 2020-09-11 | 哈尔滨工程大学 | Underwater sound direct sequence spread spectrum signal m-sequence blind estimation method based on database matching |
| US11075709B2 (en) * | 2018-02-15 | 2021-07-27 | Qualcomm Incorporated | Variable spreading factor codes for non-orthogonal multiple access |
| CN109150236B (en) * | 2018-08-01 | 2020-05-19 | 东南大学 | Variable-step length LEAP neural network-based direct sequence estimation method for pseudo code of direct sequence spread spectrum signal |
| CN113541728B (en) * | 2021-06-29 | 2022-06-17 | 中国人民解放军国防科技大学 | Method, system and medium for guided acquisition of short code signal to long code signal |
| CN113472483B (en) * | 2021-06-30 | 2023-06-02 | 西南电子技术研究所（中国电子科技集团公司第十研究所） | Blind estimation method for code element rate and code element conversion time of digital modulation signal |
| CN116232809B (en) * | 2023-01-12 | 2024-04-19 | 电子科技大学 | Synchronous long code DS-CDMA signal blind estimation method |
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Effective date of registration: 20221206 Address after: Room 407-10, floor 4, building 2, Haichuang science and technology center, Cangqian street, Yuhang District, Hangzhou City, Zhejiang Province, 311100 Patentee after: Zhejiang Zhiduo Network Technology Co.,Ltd. Address before: 314500 Tongxiang City, Jiaxing, Zhejiang, Tung Tung Road, Wu Tung Street (East) 55, Tongxiang chamber of Commerce Building 1 unit 1702, 1703 room -A-220 Patentee before: Jiaxing Beixi Electromechanical Equipment Co.,Ltd. |