CN103401661A - Integral coding/decoding method based on MIMO radar communication - Google Patents

Abstract

The invention provides an integral coding/decoding method based on MIMO radar communication. The orthogonal spread spectrum code sequence guarantees the orthogonality of bipolar phase spread spectrum code sequence based on WalsH matrix. The requirement of the radar to the detection of signal self-correlation peak value, mutual correlation peak value low side-lobe can be satisfied through the genetic algorithm. The signal encoding is based on soft spread spectrum biorthogonal encoding. To satisfy the requirement of the MIMO radar to detection signal, different spreading coding sequences can be used on different encode element positions; special sending channel can be reserved as the time and frequency synchronous standard, the first encode element position of each sending channel is reserved as the phase position standard, and special synchronous spreading codes are used on the positions. According to the method provided by the invention, conventional carrier frequency offset extraction technology, carrier phase partial extraction technology and soft spread spectrum biorthogonal decoding method are improved specifically according to the requirement of the radar/radio frequency integrate realization, accompanied by the frequency offset tracking technology with Alpha -Beta as the core, accuracy of data deviation correction is guaranteed.

Description

A kind of integrated decoding method based on the MIMO radar communication

Technical field

The present invention relates to the radar communication technology.

Background technology

Combination by radar, communication equipment, form comprehensive radio frequency integrated system, both help work, the reasonable distribution system resource of electronic equipment on real time coordination and control optimal in structure, be convenient to again realize the generalization of equipping, miniaturization and multifunction.This is to expanding the scope of application of military equipment, and the overall combat effectiveness of raising Military Electronic Equipment and reliability, maintainability, all be of great practical significance and military value.

The existing research in radio frequency integrated aspect is carried out mainly for the phased array radar system, and the integrated mode of operation of sharing based on waveform is wherein more popular research direction.Yet the limitation due to self working method, the narrow beam of tradition phased array radar is difficult to cover simultaneously the telecommunication objects such as detection, tracking target and guided missile, one's own side's aircraft, communication and detection mission must be carried out in timesharing, and the service efficiency of integral system time and energy is very limited.

MIMO(Multiple-Input Multiple-Out-put) communication, namely in cell site, place a plurality of antennas, also place a plurality of antennas in receiving station, in conjunction with Space-Time Codes, can form the MIMO communication link between cell site and receiving station, and suppress whereby channel fading, in the situation that do not increase bandwidth and antenna transmission power, improve exponentially the channel capacity of wireless communication system, reduce the error rate.

Be subjected to the inspiration of MIMO communication, Lincoln laboratory has proposed MIMO radar concept, the further popularization that centralized MIMO radar concept wherein is phase array and Digital Array Radar concept.It is divided into some with antenna array, send separately orthogonal signal waveform, and adopt the wide mode of operation of sending out receipts wide, electromagnetic energy can not be with the narrow beam of superimposed synthetic high-gain in space, cover very large spatial domain scope but form than the broad beam of low gain, increase duty ratio and integration time to make up the deficiency of antenna gain.

Work in the radar system under the MIMO pattern, target and the telecommunication object surveying, follow the tracks of are easy to be in simultaneously among the detection wave beam of MIMO radar.Therefore, the more feasible and practical value of the radio frequency integrated system take the MIMO technology as background.As long as select rational coded system, the communication information is included in the radar detection waveform with specific form, just can be when completing target following or detection, to the transmitting information of communication equipment in the wave beam range of exposures, thereby effectively promote time, the energy service efficiency of radio frequency integrated system.While using when large wide phase-coded signal, the system parameters of MIMO radar and spread spectrum communication is very approaching, and the Waveform Design of spread spectrum communication and coding and decoding scheme are also the important foundations of radio frequency integrated system.

Tamed spread spectrum is a kind of of spread spectrum communication, employing be (N, k) coding, namely with the spreading code that length is N, go to represent k position information, k position information has 2 ^kIndividual state, different states be corresponding to different spreading codes, thereby realize the spread spectrum purpose, its spread spectrum rate is that N/k(sees document: spread spectrum communication and multiple access technology thereof [M]. Zeng Xingwen, Liu Naian, Sun Xianpu. Xi'an: publishing house of Xian Electronics Science and Technology University, 2004).The spreading code that tamed spread spectrum is used must be mutually orthogonal and be had low autocorrelation peak secondary lobe and low cross correlation value, utilizes genetic algorithm meeting optimization under the prerequisite of orthogonality and have the coding of low autocorrelation peak secondary lobe and low cross correlation value.（Binary orthogonal code design for MIMO radar systems[C].Sun Ying，Zishu He，Hongming Liu，Li Jun,Shangwei Gao.2010International Symposium on Intelligent Signal Processing and Communication system(ISPACS2010),December6-8,2010.）。

Tamed spread spectrum bi-orthogonal coded scheme be on the basis of tamed spread spectrum with some bit modulation of the communication information in the phase place of carrier wave, positive and negative according to this bit, select 0 or two kinds of phase places of π.It can, in the situation that communication information amount is certain, reduce the demand to the spreading code number; Perhaps in the situation that the given information position, increase the communication information amount of information (the spread spectrum scheme research of a kind of bi-orthogonal coded M unit. fourth is defended, field red heart, Yi Kechu. radio engineering [J] .2003.); This encoding scheme is also beneficial to the confidentiality that promotes communication system.

Must consider every possible angle the demand difference of radar and communication system based on the radio frequency integrated technology of MIMO technology, solve Design of Compatibility and the use problem of radar-signal of communication.Wherein, radar requires each transmission channel signal to have low autocorrelation peak secondary lobe and low cross correlation value, realizes that DOD (electric wave departure angle) also requires between each channel transmit signal to meet strict orthogonality while measuring; And be to realize reliable information transmission efficiently, during integrated Waveform Design, need again to take into account simultaneously the problems such as amount of information and decoding synchronisation requirement.Find the key that rational coding and decoding scheme is radio frequency integrated technology under the MIMO background.

Summary of the invention

Technical problem to be solved by this invention is, a kind of MIMO of being adapted to radar communication, integrated decoding method are provided.

The present invention solves the problems of the technologies described above the technical scheme of sampling to be, a kind of integrated coding method based on the MIMO radar communication comprises the following steps:

MIMO radar setting steps: the MIMO radar arranges M transmission channel, and each passage comprises L+1 code symbols; Reserving M transmission channel is the Time and Frequency Synchronization benchmark; The 1st code symbols of all the other M-1 passage gives over to the skew benchmark, and a rear L code symbols is information bit, and each information bit has p state;

The spreading code waveform generates step:, with (M-1) Lp+M+L subcode string that genetic algorithm optimization generates, with these subcode string number consecutivelies, be C ₁, C ₂..., C _(M-1)L _P+M+L, described subcode string is the basic coding sequence as spreading code;

Information source information coding step: will need to be divided into two parts by the communication information of radar detection wave beam transmission, and encode respectively; Wherein first's information is according to the unipolarity p scale coding rule q that encodes ₁, q ₂..., q _{(M-1) L}, second portion is according to the bipolar binary coding rule b that encodes ₁, b ₂... b _{(M-1) L}Take L code element as unit, with the uniform distribution of two parts communication information in a front M-1 passage;

The sequence that transmits generates step: two parts communication information correspondence in each passage is multiplied each other, namely, utilize first's communication information to determine the subcode string of each channel information position, and the subcode string of each information bit is multiplied each other with the second portion communication information is corresponding, obtain the coded sequence of message part in detectable signal; Add skew baseline encoded PR separately in a front M-1 passage _i, wherein, PR _iWith the corresponding relation of subcode string be: PR _i=C _{(M-1) Lp+i}, i=1,2 ..., M-1; Insert the fixed sequence program TF that L+1 fixing subcode string combines in the time and frequency standards passage of reserving, finally obtain the sequence that transmits of each transmission channel of MIMO radar.

A kind of integrated coding/decoding method based on the MIMO radar communication comprises the following steps:

The data receiver step: the data X (n) that receiver receives down-conversion, samples and obtain, the systematic sampling rate is 1/T _C, T _CChip-spaced for the subcode string; Judge whether to have the prior information of current time frequency deviation, if any, the entry time synchronizing step, otherwise enter frequency deviation Search/Track initial step;

Frequency deviation Search/Track initial step: the frequency deviation between the search transmitting-receiving station

Utilization searches the frequency deviation result and starts α-βfilter, to frequency deviation

Follow the tracks of, remember;

The time synchronized step: the fixing subcode string rule of combination at the time and frequency standards passage of reserving during according to coding produces the baseband signal sequence H identical with M transmission channel of radar ₀(n), the N of 1≤n≤(L+1); With baseband signal sequence H ₀(n) be modulated at α-βfilter m-1 constantly to m frequency deviation predicted value constantly

On, m is the current reception data moment, the signal H (n) after modulation is Sampled data X (n) and modulation signal H (n) are processed, obtain result y (n), * represent conjugate complex number; Determined to receive the initial time n of signal by the peak of relevant treatment ₀, according to the initial time n that receives signal ₀Intercepting valid data X _C(n): X _C(n)=X (n), n ₀The N of≤n≤(L+1);

The carrier wave frequency deviation aligning step:

To valid data X _C(n) carry out frequency offset correction, obtain frequency offset correction valid data y _C(n), $y_C\left(n\right)=X_C\left(n\right)e^{-\mathrm{j\Δ}{\widehat{\mathrm{\ω}}}_{m/m-1}n{T}_C},$ n ₀≤n≤(L+1)N；

Carrier wave skew extraction step: intercepting frequency offset correction valid data y _C(n) data corresponding to skew benchmark in

With data Respectively with skew baseline encoded PR _iThe summation of multiplying each other, obtain summed result

I=1,2 ..., M-1; Calculate summed result

Phase place And will

Skew estimated value as i passage;

Shunt treatment step: with frequency offset correction valid data y _C(n) carry out segmentation take length N as unit, and the L segment data that will obtain sends into respectively in M-1 correlation receiver of corresponding decoding branch road the processing of decoding, the data of sending into k decoding branch road are expressed as: y _k(n)=y _C(kN+n-n ₀), k=1,2 ... L, 1≤n≤N, k=1,2 ..., M-1; The data that to send into again each correlation receiver are divided into p branch road, the signal of each branch road respectively with the summation of multiplying each other of the subcode string of its corresponding states;

K=1,2 ... L, i=1,2 ... M-1, q=1,2 ... p;

Be k road signal in i correlation receiver with subcode string C _{(i-1) Lp+ (k-1) p+q}The result that multiplies each other and sue for peace;

The skew aligning step: the signal of each branch road multiply by skew and estimates the factor with the subcode string of its corresponding states summed result that multiplies each other respectively, obtains skew and proofreaies and correct result;

I=1,2 ... M-1; K=1,2 ..., L; Q=1,2 ..., p, wherein,

Be k road signal in i correlation receiver with the summation of multiplying each other of its corresponding states subcode string

Skew proofread and correct result,

The skew that is i passage is estimated the factor;

Compare decision steps: skew is proofreaied and correct result

Get real part

Compare judgement, obtain the part 1 communication information q that the radar emission end transmits _{(i-1) L+k}: q _{(i-1) L+k}=q _i,k, i=1,2 ... M-1; K=1,2 ..., L, q _i,kIt is the maximum value output branch number of i correlation receiver of k decoding branch road; The judgement skew is proofreaied and correct result

Get real part

Symbol, obtain the part 2 communication information b that the radar emission end transmits _{(i-1) L+k}:

I=1,2 ... M-1; K=1,2 ..., L; With part 1 communication information q _{(i-1) L+k}With part 2 communication information b _{(i-1) L+k}Make up respectively, obtain two parts communication information that MIMO radar emission end passes over.

The orthogonal spectrum expansion coded sequence is guaranteed the orthogonality of bipolarity Phase Encode Spread Spectrum Technology sequence based on the WalsH matrix.Meet the requirement of radar to detectable signal autocorrelation peak, the low secondary lobe of cross-correlation peak value by genetic algorithm.Signal coding is based on the thought of tamed spread spectrum bi-orthogonal coded., for meeting the requirement of MIMO radar to detectable signal, use different spread spectrum coding sequences on different code symbols positions; Reserve special transmission channel as the Time and Frequency Synchronization benchmark, first code symbols position of each transmission channel is also to give over to phase reference, the special synchronous spreading code of arrangement and use on these positions.The current demand that the present invention is directed to radar/radio frequency integrated has been carried out perfect targetedly to existing carrier wave frequency deviation extractive technique, carrier wave skew extractive technique, tamed spread spectrum biorthogonal coding/decoding method, be aided with alpha-beta and be core the frequency offset tracking technique guarantee accuracy of data frequency offset corrections.When keeping MIMO radar detection, tracking performance, solved the problem of utilizing the radar detection waveform to transmit the communication information.

Further, during based on the integrated decoding of MIMO radar communication, provide a kind of α-βfilter state step of updating, specific as follows:

With α-βfilter m-1 constantly to m frequency deviation predicted value constantly

Centered by, choose 2G+1 frequency deviation point:

G ∈ [G, G],

For g the frequency deviation point of choosing; T _CChip-spaced for the subcode string; With baseband signal sequence H ₀(n) be modulated to respectively on these frequencies, obtain modulation signal H _g(n); $H_g\left(n\right)=H_0\left(n\right)e^{-\mathrm{jn\Δ}{\widehat{\mathrm{\ω}}}_g{T}_C},$ n∈[1,(L+1)N]；

Utilize valid data X _C(n) to modulation signal H _g(n) process the output peak value U after processing _gFor,

G=-G ,-G+1 ..., G; Relatively the peak value Output rusults, find maximum output peak value U _j, U _j=max (U _g);

According to U _jCorresponding frequency △ ω ' _mCalculate the measuring value of the frequency deviation estimation of m constantly

For:

Wherein, k _dFor error voltage linear fit slope, U _j+1Be j+1 the output peak value that frequency is corresponding, U _j-1Be j-1 the output peak value that frequency is corresponding;

Calculate △ (the △ ω of the frequency deviation estimation of m constantly _m) residual error is

Obtain the frequency deviation estimated value of current time

Calculate the estimated value of current time frequency deviation rate of change

△ T is the time interval between twice data acquisition;

Calculate next frequency deviation estimated value constantly

And the estimated value of frequency deviation rate of change

$\begin{array}{c}\left[\begin{array}{c}\mathrm{\&Delta;}{\widehat{\mathrm{\&omega;}}}_{m+1/m}\\ {\hat{v}}_{m+1/m}\end{array}\right]=\end{array}\begin{array}{c}\left[\begin{array}{cc}1& \mathrm{\&Delta;<figure-callout\; id="0"\; label="T"\; filenames="HDA00003640416900022.png,HDA00003640416900023.png"\; state="\{\{state\}\}">T</figure-callout>}\\ 0& 1\end{array}\right]\end{array}\left[\begin{array}{c}\mathrm{\&Delta;}{\widehat{\mathrm{\&omega;}}}_{m/m}\\ {\hat{v}}_{m/m}\end{array}\right].$

Of the present inventionly usefully be, survey and follow the tracks of target is normal for the radar under the MIMO technical background/communication radio frequency integral system provides a kind of coding, coding/decoding method to make the MIMO radar to keep, utilize simultaneously radar signal to the target transmission of information in beam coverage, complete the tasks such as guidance or monitoring.

Description of drawings

Fig. 1 is the communications reception schematic diagram.

Fig. 2 is the schematic diagram of phase partial extraction.

Fig. 3 is the correlation reception schematic diagram of k information bit of i passage.

Fig. 4 is N=128, during L=6, the 4th passage from ambiguity diagram.

Fig. 5 is N=128, during L=6, and the mutual ambiguity diagram of the 2nd, 3 passages.

Fig. 6 is the relation curve of snr of received signal and the error rate.

Embodiment

, for better description, carried out as giving a definition:

Spread spectrum subcode string: obtained by genetic algorithm optimization, prepare to be referred to as spread spectrum subcode string as the basic coding sequence of spreading code, referred to as the subcode string;

Code symbols: when signal is encoded, the subcode string need to be made up according to certain rule, wherein, the position that is used for placing the subcode string just is referred to as coding unit.

Information bit: the coding unit that carries the communication information is referred to as information bit.

The skew benchmark: be used for realizing that phase deviation extracts is referred to as the skew benchmark, first coding unit of each transmission channel all gives over to the skew benchmark.

The time and frequency standards passage: the transmission channel that carrier synchronization and time reference are provided that is specifically designed to of reservation is referred to as the time and frequency standards passage.

Unipolarity p scale coding: each code element of signal has 1,2 ..., p is p state altogether, with getting the method that corresponding states numerical value encodes after information quantization, is referred to as unipolarity p scale coding.

One, cataloged procedure:

If the MIMO radar has M transmission channel, each passage comprises L+1 code symbols.Reserving M transmission channel is the Time and Frequency Synchronization benchmark; The 1st code symbols of all the other M-1 passage gives over to the skew benchmark, and a rear L code symbols is information bit, and each information bit has p state.A kind of integrated spread spectrum phase code detectable signal generation method that can take into account MIMO radar target acquisition, tracking and information transfer function has following steps:

Step 1 spreading code Waveform Design: going out (M-1) Lp+M+L subcode string with genetic algorithm optimization, is C with these subcode string number consecutivelies ₁, C ₂..., C _{(M-1) Lp+M+L}

Step 2 information source information coding:

Step 2-1 will need to be divided into two parts by the communication information of radar detection wave beam transmission, encode respectively.Wherein first's information is encoded according to unipolarity p scale coding rule, and second portion is encoded according to the bipolar binary coding rule.Two parts communication information that obtains after coding can be expressed as respectively:

Part 1: q ₁, q ₂..., q _{(M-1) L}

Part 2: b ₁, b ₂... b _{(M-1) L}

Wherein, 1≤q _j≤ p; b _j=1 or-1; J=1,2 ..., (M-1) L.The single frames maximum fault information is (M-1) (log ₂(p ^LThe bit of)+L).

Step 2-2 is take L code element as unit, with the uniform distribution of two parts communication information to a front M-1 passage.Allocation result is as shown in table 1:

The communication information that each passage of table 1. need to be modulated

Step 3 generates the MIMO radar quadrature biphase coding sequence that transmits:

Step 3-1 utilizes first's communication information to determine the subcode string of each channel information position, and the subcode string of information bit is multiplied each other with the second portion communication information is corresponding, obtain the coded sequence of message part in detectable signal, wherein the coding waveforms of k information bit of i passage can be expressed as:

$U_{i,k}=b_{(i-1)L+k}*C_{(i-1)\mathrm{Lp}+(k-1)p+q_{(i-1)L+k}}$

Step 3-2 adds skew baseline encoded PR separately in a front M-1 passage _i, PR _iWith the corresponding relation of subcode string be:

PR _i=C _{（M-1）Lp+i},i=1,2,...,M-1

Insert the fixed sequence program that L+1 fixing subcode string combines in the time and frequency standards passage of reserving, have:

TF=[TF ₁,...,TF _L+1]

Wherein, TF _j=C _{(M-1) Lp+M-1+j}, j=1,2 ... L+1.

Finally obtain the sequence that transmits of each transmission channel of MIMO radar, as shown in table 2:

Each channel signal coding of table 2.

Step 4 generates and transmits:

Produce the up-converter circuit of equipment and each transmission channel via digital signal, the coded sequence of each passage is modulated on the radar operating frequency, form the detectable signal of MIMO integral system special use.

The integrated coding of radar communication under the MIMO background need to meet the basic demand of MIMO radar (the autocorrelation peak secondary lobe that each transmission channel signal of radar is low and low cross correlation value, and strict orthogonality) under prerequisite, the communication information is included in each transmission channel of radar.

The present invention utilizes the biorthogonal thought of tamed spread spectrum to encode to each transmission channel of radar, carries out the optimization of spreading code with genetic algorithm.For successfully demodulating entrained information in tamed spread spectrum bi-orthogonal coded phase place, the present invention realizes first code symbols of each passage the skew estimation of own passage as the skew benchmark; Simultaneously, for realizing the tracking of time synchronized and carrier wave frequency deviation, the present invention reserves special passage as the time and frequency standards passage, and this passage does not carry the communication information, sends all the time the known code signal of specific both sides.

After integrated coding, each transmission channel of radar still meets strict orthogonality; When Fig. 4, Fig. 5 have drawn transmission channel and have counted M=5, between channel signal from, ambiguity function figure mutually, from the ambiguity diagram result as can be known, in integral system, each transmission channel signal of radar has low autocorrelation peak secondary lobe and low cross correlation value.

Two, decode procedure:

Under integrated background, the decode procedure of communications receiving equipment mainly comprises following content:

(1) time synchronized

Under integrated mode of operation, radar transmits the communication information with the form of pulse to communication equipment, and therefore, at first communication equipment needs to realize time synchronized, could intercept the effective impulse signal, carries out information extraction.

(2) carrier wave frequency deviation is followed the tracks of

The radar and communications receiving equipment adopts different local oscillators former, receives signal after Digital Down Convert, and signal still can be subject to the modulation of carrier wave frequency deviation, and this frequency deviation can affect follow-up decoding to be processed, and therefore, communications receiving equipment need to be followed the tracks of memory to carrier wave frequency deviation.Utilize α-βfilter to realize the real-time memory of frequency deviation value, can guarantee the accuracy of data frequency offset correction.

(3) phase partial extraction

Each channel signal is in transmitting procedure, and initial phase has certain deviation, and this phase deviation can affect the accurate demodulation of each channel signal initial phase, thereby affects the extraction of the entrained second portion communication information of radar detection waveform.Therefore, the communication decoding must extract the phase deviation of each channel signal, and each channel signal is carried out phase compensation.

(4) communication decoding

As shown in Figure 1, the decoding concrete steps are as follows:

Step 1 data receiver:

Step 1-1, from the data that receiver receives down-conversion, samples and obtain, is designated as X (n), and the systematic sampling rate is 1/T _C, T _CChip-spaced for the subcode string.

Step 1-2 judges whether receiving terminal has the prior information of current time frequency deviation, if any directly turning step 3, otherwise turns step 2.

Step 2 frequency deviation Search/Track is initial

Frequency deviation between step 2-1 search transmitting-receiving station

Step 2-2 utilizes some Search Results of step 2-1

Start α-βfilter, it is right to start

Follow the tracks of, remember.

Step 3 time synchronized

If this moment that receives data is the m moment, α-βfilter m-1 to m frequency deviation predicted value constantly is constantly

Step 3-1 produces the baseband signal sequence H identical with M transmission channel of radar according to coding rule ₀(n), the N of 1≤n≤(L+1) is expressed as form and is:

TF 1

TF 2

…

TF L+1

Step 3-2 is with H ₀(n) be modulated at On, the signal after modulation is designated as H (n), and H (n) can be expressed as:

$H\left(n\right)=H_0\left(n\right)e^{\left(\mathrm{j\&Delta;}{\widehat{\mathrm{\&omega;}}}_{m/m-1}n{T}_C\right)}---\left(1\right)$

Step 3-4 carries out relevant treatment with H (n), X (n) according to the following formula.

$y\left(n\right)=\frac{1}{N}{\mathrm{\&Sigma;}}_{i=1}^{(L+1)N}X(n+i)H^{*}\left(i\right)---\left(2\right)$

Step 3-5 determines to receive the initial time n of signal according to the peak of related operation ₀, and the intercepting valid data, be designated as X _C(n):

X _C(n)=X(n),n ₀≤n≤(L+1)N (3)

Step 4 carrier wave frequency deviation is proofreaied and correct

Utilize following formula to X _C(n) carry out frequency offset correction:

$y_C\left(n\right)=X_C\left(n\right)e^{-\mathrm{j\&Delta;}{\widehat{\mathrm{\&omega;}}}_{m/m-1}n{T}_C},{\mathrm{<figure-callout\; id="0"\; label="n"\; filenames="HDA00003640416900022.png,HDA00003640416900023.png"\; state="\{\{state\}\}">n</figure-callout>}}_0\&le;n\&le;(L+1)N---\left(4\right)$

Step 5 is extracted the carrier wave skew:

Step 5-1 intercepts y _C(n) data corresponding to skew benchmark in are expressed as:

$y_C^{\left(1\right)}\left(n\right)=y_C\left(n\right),1\&le;n\&le;N---\left(5\right)$

Step 5-2 as shown in Figure 2, will

Respectively with PR _i, i=1,2 ..., M-1 multiplies each other and sues for peace:

$R_C^i=\underset{n=0}{\overset{N}{\mathrm{\&Sigma;}}}{y}_C^{\left(1\right)}\left(n\right)\&CenterDot;P{R}_i\left(n\right),i=\mathrm{1,2},\&CenterDot;\&CenterDot;\&CenterDot;,M-1---\left(6\right)$

Step 5-3 calculated complex

I=1,2 ..., the phase place of M-1, be designated as

I=1,2 ..., M-1, and will

Skew estimated value as i passage.

Step 6, take length N as unit, is processed valid data along separate routes.

Step 6-1 is with y _C(n) carry out segmentation take length N as unit, and the L segment data that will obtain sends into respectively in M-1 correlation receiver of corresponding decoding branch road the processing of decoding, single decoding branch road as shown in Figure 3.Wherein, the data of sending into k decoding branch road can be expressed as:

y _k(n)=y _C(kN+n-n ₀),k=1,2,…L,1≤n≤N (7)

Step 6-2 as shown in Figure 3, is divided into p branch road with the data of sending into each correlation receiver, the signal of each branch road respectively with the summation of multiplying each other of the subcode string of its corresponding states, as formula (8):

$Y_q^{i,k}=\underset{n=1}{\overset{N}{\mathrm{\&Sigma;}}}{y}_k\left(n\right)C_{(i-1)\mathrm{Lp}+(k-1)p+q}\left(n\right);$ (8)

k=1,2,…L,i=1,2,…M-1,q=1,2,…p

(8) in formula

Be k road signal in i correlation receiver with subcode string C _{(i-1) Lp+ (k-1) p+q}The result that multiplies each other and sue for peace.

Step 7 skew is proofreaied and correct

Will

Multiply by skew and estimate the factor

Result is as follows:

Step 8 is relatively adjudicated, and obtains the communication information that the radar emission end transmits

Step 8-1 will

Get real part and compare judgement, the maximum value output branch number of i correlation receiver of k decoding branch road of note is q _i,k, obtain the part 1 communication information that the radar emission end transmits:

q _(i-1)L+k=q _i,k,i=1,2,…M-1;k=1,2,…,L (10)

Step 8-2 judgement

Symbol, obtain the part 2 communication information that the radar emission end transmits:

$b_{(i-1)L+k}=\frac{Y_{q_{(i-1)L+k}}^{\&prime;i,k}}{\left|Y_{q_{(i-1)L+k}}^{\&prime;i,k}\right|},i=\mathrm{1,2},\&CenterDot;\&CenterDot;\&CenterDot;M-1;k=\mathrm{1,2},\&CenterDot;\&CenterDot;\&CenterDot;,L---\left(11\right)$

Step 8-3 is with q _{(i-1) L+k}, b _{(i-1) L+k}, i=1,2 ... M-1, k=1,2 ..., L makes up respectively, obtains two parts communication information that MIMO radar emission end passes over.

Step 9 α-βfilter state upgrades

Step 9-1 with

Centered by, choose 2G+1 frequency deviation point:

$\mathrm{\&Delta;}{\widehat{\mathrm{\&omega;}}}_g=\mathrm{\&Delta;}{\widehat{\mathrm{\&omega;}}}_{m/m-1}+\frac{g}{4(L+1)N{T}_C},g\&Element;[-G,G]---\left(12\right)$

Step 9-2 is with H ₀Be modulated to respectively on these frequencies:

$H_g\left(n\right)=H_0\left(n\right)e^{-\mathrm{jn\&Delta;}{\widehat{\mathrm{\&omega;}}}_g{T}_C},n\&Element;[1,(L+1)N]---\left(13\right)$

Step 9-3 carries out relevant treatment to the data that step 4 obtains respectively with these bursts that modulate, and note output peak value is U _g, g=-G ,-G+1 ..., G.

$U_g=\left|\frac{1}{N}{\mathrm{\&Sigma;}}_{n=1}^{(L+1)N}{X}_C\left(n\right){H^{*}}_g\left(n\right)\right|---\left(14\right)$

Step 9-4 is the peak value Output rusults relatively, finds maximum output peak value to be designated as U _j=max (U _g, g=-G+1 ..., G-1), with U _jCorresponding frequency is designated as △ ω ' _m, the measuring value that frequency deviation is estimated is

$\mathrm{\&Delta;}{\stackrel{\&OverBar;}{\mathrm{\&omega;}}}_m=\mathrm{\&Delta;}{\mathrm{\&omega;}}_m^{\&prime;}+\frac{1}{k_d}\&CenterDot;\frac{U_{j+1}-U_{j-1}}{U_j}---\left(15\right)$

Wherein, k _dFor error voltage linear fit slope.

The residual error that step 9-5 calculates the frequency deviation estimation is

$\mathrm{\&Delta;}\left(\mathrm{\&Delta;}{\mathrm{\&omega;}}_m\right)=\mathrm{\&Delta;}{\stackrel{\&OverBar;}{\mathrm{\&omega;}}}_m-\mathrm{\&Delta;}{\widehat{\mathrm{\&omega;}}}_{m/m-1}---\left(16\right)$

Step 9-6 utilizes formula

$\mathrm{\&Delta;}{\widehat{\mathrm{\&omega;}}}_{m/m}=\mathrm{\&Delta;}{\widehat{\mathrm{\&omega;}}}_{m/m-1}+\mathrm{\&alpha;}\&CenterDot;\mathrm{\&Delta;}\left(\mathrm{\&Delta;}{\mathrm{\&omega;}}_m\right)---\left(17\right)$

Obtain the frequency deviation estimated value of current time

Step 9-7 utilizes formula

${\hat{v}}_{m/m}={\hat{v}}_{m/m-1}+\mathrm{\&beta;}\frac{\mathrm{\&Delta;}\left(\mathrm{\&Delta;}{\mathrm{\&omega;}}_m\right)}{\mathrm{\&Delta;T}}---\left(18\right)$

Calculate the estimated value of current time frequency deviation rate of change In formula, △ T is the time interval between twice data acquisition.

Step 9-8 utilizes formula

$\begin{array}{c}\left[\begin{array}{c}\mathrm{\&Delta;}{\widehat{\mathrm{\&omega;}}}_{m+1/m}\\ {\hat{v}}_{m+1/m}\end{array}\right]=\end{array}\begin{array}{c}\left[\begin{array}{cc}1& \mathrm{\&Delta;<figure-callout\; id="0"\; label="T"\; filenames="HDA00003640416900022.png,HDA00003640416900023.png"\; state="\{\{state\}\}">T</figure-callout>}\\ 0& 1\end{array}\right]\end{array}\left[\begin{array}{c}\mathrm{\&Delta;}{\widehat{\mathrm{\&omega;}}}_{m/m}\\ {\hat{v}}_{m/m}\end{array}\right]---\left(19\right)$

Calculate next frequency deviation predicted value, update mode variable constantly.

Embodiment

One, coding

If M=5, L=6, p=2, reserve the 5th passage as the time and frequency standards passage; And suppose the chip width Tc=10 of subcode string ^-6S, subcode string length N=128, carrier frequency ω/2 π=10 ⁹Hz.

The 1st step, utilize genetic algorithm obtain 59 long be 128 the subcode string that satisfies condition and to its numbering.

In the 2nd step, with MATLAB, produce at random the part 1 communication information and the part 2 communication information is respectively:

Part 1: 2,1,2,2,2,1,1,2,2,1,1,2,1,2,2,1,2,1,2,2,2,2,2,2.

Part 2 :-1,1,1 ,-1 ,-1,1,1,1,1 ,-1 ,-1 ,-1,1 ,-1 ,-1,1,1 ,-1 ,-1,1 ,-1 ,-1 ,-1 ,-1.

In the 3rd step, be assigned to two parts communication information respectively in the information bit of 4 transmission channels, and allocation result is as shown in table 3:

The communication information that each passage of table 3. need to be modulated

The 4th step, choose corresponding subcode string by the part 1 information in table 3 for the information bit of each transmission channel, part 2 information is selected subcode string modulation initial phase, thus it is as follows to obtain the coding of front 4 the transmission channel information bits of radar:

First passage :-C ₂, C ₃, C ₆,-C ₈,-C ₁₀, C ₁₁

Second channel: C ₁₃, C ₁₆, C ₁₈,-C ₁₉,-C ₂₁,-C ₂₄

Third channel: C ₂₅,-C ₂₈,-C ₃₀, C ₃₁, C ₃₄,-C ₃₅

Four-way :-C ₃₈, C ₄₀,-C ₄₂,-C ₄₄,-C ₄₆,-C ₄₈

In the 5th step, skew benchmark position and the 5th passage (Time and Frequency Synchronization passage) coding for front 4 passages obtain the final coding result of each transmission channel of radar as shown in table 4:

Each transmission channel coding of table 4. radar

Fig. 4, Fig. 5 have provided the mutual ambiguity diagram from ambiguity diagram and the 2nd, 3 passages of the 4th transmission channel.Can see from the result of Fig. 4, Fig. 5, transmit and have very low autocorrelation peak secondary lobe and very little cross correlation value; And, being the figure spike as can be known by signal from ambiguity diagram, the radar detection waveform is comparatively responsive to doppler information, detects the slower-velocity target ability strong, and has range resolution ratio preferably.In addition, adopt the broad beam irradiation of low gain due to the MIMO radar, so than traditional phased array radar, have better anti-intercepting and capturing performance.

Two, decoding

If the distance between communication equipment and radar is 5000m, carrier wave frequency deviation △ ω/2 π=500Hz, snr of received signal are 12dB, and the receiving equipment sample rate is 1/T _C

In the 1st step, carrier wave frequency deviation is caught.

In the 2nd step, utilize the result in the 1st step to carry out time synchronized and carrier wave frequency deviation correction to next group data.

In the 3rd step, the signal after proofreading and correct is carried out skew estimate.

In the 4th step, communicate decoding, and decoded result is as follows:

First's information after decoding

Second portion information after decoding

In the 5th step, calculate the frequency deviation predicted value of current time to the lower moment.

By decoded result as can be known, when signal to noise ratio was 12dB, despreading coding/decoding method of the present invention can accurately obtain original encoding information.

Get signal to noise ratio-30～30dB, draw relation curve such as Fig. 6 of signal to noise ratio and the error rate, by curve as can be known, when signal to noise ratio during greater than 10dB, but despreading coding/decoding method Exact Solutions of the present invention obtains the communication information that comprises in the radar emission signal.

Claims (3)

1. the integrated coding method based on the MIMO radar communication, is characterized in that, comprises the following steps:

MIMO radar setting steps: the MIMO radar arranges M transmission channel, and it is the Time and Frequency Synchronization benchmark that each passage comprises M transmission channel of L+1 code symbols reservation; The 1st code symbols of all the other M-1 passage gives over to the skew benchmark, and a rear L code symbols is information bit, and each information bit has p state;

The spreading code waveform generates step:, with (M-1) Lp+M+L subcode string that genetic algorithm optimization generates, with these subcode string number consecutivelies, be C ₁, C ₂..., C _{(M-1) Lp+M+L}, described subcode string is the basic coding sequence as spreading code;

Information source information coding step: will need to be divided into two parts by the communication information of radar detection wave beam transmission, and encode respectively; Wherein first's information is according to the unipolarity p scale coding rule q that encodes ₁, q ₂..., q _{(M-1) L}, second portion is according to the bipolar binary coding rule b that encodes ₁, b ₂... b _{(M-1) L}Take L code element as unit, with the uniform distribution of two parts communication information in a front M-1 passage;

The sequence that transmits generates step: two parts communication information correspondence in each passage is multiplied each other, obtain the coded sequence of message part in detectable signal; Add skew baseline encoded PR separately in a front M-1 passage _i, wherein, PR _iWith the corresponding relation of subcode string be: PR _i=C _{(M-1) Lp+i}, i=1,2 ..., M-1; Insert the fixed sequence program TF that L+1 fixing subcode string combines in the time and frequency standards passage of reserving, finally obtain the sequence that transmits of each transmission channel of MIMO radar.

2. the integrated coding/decoding method based on the MIMO radar communication, is characterized in that, comprises the following steps:

The data receiver step: the data X (n) that receiver receives down-conversion, samples and obtain, the systematic sampling rate is 1/T _C, T _CChip-spaced for the subcode string; Judge whether to have the prior information of current time frequency deviation, if any, the entry time synchronizing step, otherwise enter frequency deviation Search/Track initial step;

Frequency deviation Search/Track initial step: the frequency deviation between the search transmitting-receiving station

Utilization searches the frequency deviation result and starts α-βfilter, to frequency deviation

Follow the tracks of, remember;

The time synchronized step: the fixing subcode string rule of combination at the time and frequency standards passage of reserving during according to coding produces the baseband signal sequence H identical with M transmission channel of radar ₀(n), the N of 1≤n≤(L+1); With baseband signal sequence H ₀(n) be modulated at α-βfilter m-1 constantly to m frequency deviation predicted value constantly

On, m is the current reception data moment, the signal H (n) after modulation is Sampled data X (n) and modulation signal H (n) are processed, obtain result y (n),

* represent conjugate complex number; Determined to receive the initial time n of signal by the peak of relevant treatment ₀, according to the initial time n that receives signal ₀Intercepting valid data X _C(n): X _C(n)=X (n), n ₀The N of≤n≤(L+1);

The carrier wave frequency deviation aligning step:

To valid data X _C(n) carry out frequency offset correction, obtain frequency offset correction valid data y _C(n), $y_C\left(n\right)=X_C\left(n\right)e^{-\mathrm{j\&Delta;}{\widehat{\mathrm{\&omega;}}}_{m/m-1}n{T}_C},$ n ₀≤n≤(L+1)N；

Carrier wave skew extraction step: intercepting frequency offset correction valid data y _C(n) data corresponding to skew benchmark in

With data

Respectively with skew baseline encoded PR _iThe summation of multiplying each other, obtain summed result

$R_C^i=\underset{n=0}{\overset{N}{\mathrm{\&Sigma;}}}{y}_C^{\left(1\right)}\left(n\right)\&CenterDot;P{R}_i\left(n\right),$ I=1,2 ..., M-1; Calculate summed result

Phase place

I=1,2 ..., M-1, and will

Skew estimated value as i passage;

Shunt treatment step: with frequency offset correction valid data y _C(n) carry out segmentation take length N as unit, and the L segment data that will obtain sends into respectively in M-1 correlation receiver of corresponding decoding branch road the processing of decoding, the data of sending into k decoding branch road are expressed as: y _k(n)=y _C(kN+n-n ₀), k=1,2 ... L, 1≤n≤N, k=1,2 ..., M-1; The data that to send into again each correlation receiver are divided into p branch road, the signal of each branch road respectively with the summation of multiplying each other of the subcode string of its corresponding states;

K=1,2 ... L, i=1,2 ... M-1, q=1,2 ... p;

Be k road signal in i correlation receiver with subcode string C _{(i-1) Lp+ (k-1) p+q}The result that multiplies each other and sue for peace;

The skew aligning step: the signal of each branch road multiply by skew and estimates the factor with the subcode string of its corresponding states summed result that multiplies each other respectively, obtains skew and proofreaies and correct result;

I=1,2 ... M-1; K=1,2 ..., L; Q=1,2 ..., p, wherein,

Be k road signal in i correlation receiver with the summation of multiplying each other of its corresponding states subcode string

Skew proofread and correct result,

The skew that is i passage is estimated the factor;

Compare decision steps: skew is proofreaied and correct result

Get real part

Compare judgement, obtain the part 1 communication information q that the radar emission end transmits _{(i-1) L+k}: q _{(i-1) L+k}=q _i,k, i=1,2 ... M-1; K=1,2 ..., L, q _i,kIt is the maximum value output branch number of i correlation receiver of k decoding branch road; The judgement skew is proofreaied and correct result Get real part

Symbol, obtain the part 2 communication information b that the radar emission end transmits _{(i-1) L+k}:

I=1,2 ... M-1; K=1,2 ..., L; With part 1 communication information q _{(i-1) L+k}With part 2 communication information b _{(i-1) L+k}Make up respectively, obtain two parts communication information that MIMO radar emission end passes over.

3. a kind of integrated coding/decoding method based on the MIMO radar communication as claimed in claim 1, is characterized in that, also comprises α-βfilter state step of updating:

With α-βfilter m-1 constantly to m frequency deviation predicted value constantly

Centered by, choose 2G+1 frequency deviation point:

G ∈ [G, G],

For g the frequency deviation point of choosing; T _CChip-spaced for the subcode string; With baseband signal sequence H ₀(n) be modulated to respectively on these frequencies, obtain modulation signal H _g(n); $H_g\left(n\right)=H_0\left(n\right)e^{-\mathrm{jn\&Delta;}{\widehat{\mathrm{\&omega;}}}_g{T}_C},$ n∈[1,(L+1)N]；

Utilize valid data X _C(n) to modulation signal H _g(n) process the output peak value U after processing _gFor,

G=-G ,-G+1 ..., G; Relatively the peak value Output rusults, find maximum output peak value U _j, U _j=max (U _g);

According to U _jCorresponding frequency △ ω ' _mCalculate the measuring value of the frequency deviation estimation of m constantly

For:

Wherein, k _dFor error voltage linear fit slope, U _j+1Be j+1 the output peak value that frequency is corresponding, U _j-1Be j-1 the output peak value that frequency is corresponding;

Calculate △ (the △ ω of the frequency deviation estimation of m constantly _m) residual error is

Obtain the frequency deviation estimated value at current quarter $\mathrm{\&Delta;}{\widehat{\mathrm{\&omega;}}}_{m/m},\mathrm{\&Delta;}{\widehat{\mathrm{\&omega;}}}_{m/m}=\mathrm{\&Delta;}{\widehat{\mathrm{\&omega;}}}_{m/m-1}+\mathrm{\&alpha;}\&CenterDot;\mathrm{\&Delta;}\left(\mathrm{\&Delta;}{\mathrm{\&omega;}}_m\right);$ Calculate the estimated value of current time frequency deviation rate of change

△ T is the time interval between twice data acquisition;

Calculate next frequency deviation estimated value constantly And the estimated value of frequency deviation rate of change

$\begin{array}{c}\left[\begin{array}{c}\mathrm{\&Delta;}{\widehat{\mathrm{\&omega;}}}_{m+1/m}\\ {\hat{v}}_{m+1/m}\end{array}\right]=\end{array}\begin{array}{c}\left[\begin{array}{cc}1& \mathrm{\&Delta;T}\\ 0& 1\end{array}\right]\end{array}\left[\begin{array}{c}\mathrm{\&Delta;}{\widehat{\mathrm{\&omega;}}}_{m/m}\\ {\hat{v}}_{m/m}\end{array}\right].$

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