CN101355374A - Method for generating signal of non-interference quasi-synchronous CDMA communication system - Google Patents

Abstract

The invention discloses a method for generating a signal for an interference-free quasi-synchronous CDMA communication system. A spectrum spreading sequence encode block is a sequence with the zero correlation property generated by an optimal self-correlation sequence and a Hadamard matrix and is suitable for a quasi-synchronous CDMA communication system. When the maximum synchronous error of the system and the maximum multipath delay of the channel are extended within the regulated range, the interference-free transmission is realized. The parameter of the spectrum spreading sequence encode block and the efficiency of the system can be adjusted in real time according to practical factors and to select flexibly. The method lowers the requirement of the CDMA communication system on the power control and the synchronization, and reduces the complexity of realizing the system.

Description

A kind of signal creating method of non-interference quasi-synchronous CDMA communication system

Technical field

The present invention relates to a kind of direct spreading sequence, particularly a kind of signal creating method of non-interference quasi-synchronous CDMA communication system.

Background technology

In order to reduce the interference in the cdma communication system, people have proposed synchronous CDMA communications system, and the Walsh sign indicating number of employing quadrature or Adachi sign indicating number are as the frequency expansion sequence collection.For mobile communication system, the accurately assurance not too easily synchronously of up link, and also the multipath transmisstion of wireless channel makes system synchronization become difficult more.The intersymbol their cross correlation of Walsh sign indicating number or Adachi sign indicating number only is zero synchronously the time, when between code character when asynchronous cross correlation value non-vanishing, just exist multiple access to disturb.Because the existence of near-far interference will further reduce the performance of synchronous code division multiple access communication system, and power system capacity is restricted.In order to alleviate the influence of near-far interference as far as possible, in utility systems such as IS-95, adopted complicated power control techniques.Reduce the requirement of system to synchronization accuracy, the someone proposes synchronously accurate or near-synchronous cdma communication system in recent years, make the synchronous error of system be controlled within the certain limit (as one or several chip period), and on Spreading Sequences Designs, launched research work.

At this situation, designed spread spectrum sequence code group (this sequence has minimum or desirable correlation function near the certain limit zero time delay) in recent years with low/zero correlation block.By means of low/zero-correlation zone sequence code character, can realize that anti-multipath disturbs and the quasi-synchronous CDMA system of superior performance.More existing at present relevant patents as Chinese patent PCT/CN98/00151 (CN1175828A), adopt a kind of ternary frequency expansion sequence collection with zero correlation block; Japan Patent TY99002 (11-023252) adopts a kind of binary frequency expansion sequence collection with zero correlation block; Or the like.

In the ideal case, the frequency expansion sequence collection that uses in the cdma communication system should have following correlation properties: the auto-correlation function of each frequency expansion sequence should be an impulse function, and promptly except that zero time delay, its value should be zero everywhere; The cross-correlation function value of every pair of frequency expansion sequence should be zero everywhere.

Unfortunately, no matter be binary, polynary or sequence of complex numbers, the verified spread spectrum sequence code group with this desirable correlation properties is non-existent.That is to given sequence length N and number M, maximum auto-correlation function limit peak value and maximum cross correlation functional value can not be zero simultaneously, and they are subjected to the restriction of some theoretical circles, when requiring one to diminish, another must increase, as Welch circle, Sidelnikov circle, Sarwate circle etc.

Though can not design spread spectrum sequence code group, can design the zero correlation block or the low relevant spread spectrum sequence code group of distinguishing that near zero time delay, have certain-length with desirable auto-correlation and their cross correlation.This respect has had some paper publishings.For example, " A generalized QS-CDMA system and the designof new spreading codes, IEEE Trans.on Vehicular Technology; vol.47; no.4, pp.1268-1275, November 1998 (a kind of popularization QS-CDMA system and novel spreading code design; IEEE vehicle technology transactions; the 47th volume, the 4th phase, 1268-1275 page or leaf; in November, 1998) " proposed the method that a kind of design has the spread spectrum sequence code group in low relevant district; " A class of binarysequences with zero correlation zone; IEE Electronics Letters, vol.35, no.10; pp.777-779; May 1999 (class has the binary sequence of zero correlation block, IEE electronics wall bulletin, the 35th volume; the 10th phase; 777-779 page or leaf, in May, 1999) " provided a kind of binary complementary series that utilizes to designing the method for the spread spectrum sequence code group with zero correlation block; " Lower bounds on thecorrelation of sequence set with low or zero correlation zone; IEEElectronics Letters, vol.36, no.6; pp.551-552; Mar 2000 (the correlation lower limit of low/zero-correlation zone sequence, IEE electronics wall bulletin, the 36th volume; the 6th phase; 551-552 page or leaf, in March, 2000) " provided the theoretical limits about the spread spectrum sequence code group with zero correlation block or low relevant district.

Sequence sets S={S for the frequency expansion sequence that to have M cycle be N ⁽ⁱ⁾, i=1,2 ..., M} presses following formula definition zero correlation block Z _Cz:

R wherein _{I, j}(τ) be sequence S ⁽ⁱ⁾With S ^(j)Cross-correlation function value at time delay τ place.According to this definition, we claim that this set of signals S is ZCZ-(N, M, a Z _Cz) the frequency expansion sequence collection.Tang-Fan-Matsufuji circle shows, for any ZCZ-(N, M, Z _Cz) the frequency expansion sequence collection, its parameter all should satisfy MZ _Cz≤ N.

Summary of the invention

The purpose of this invention is to provide a kind of non-interference quasi-synchronous CDMA communication system signal creating method of simply, easily realizing and can reach theoretical circles, make code division multiple address communication system realize noiseless transmission under certain condition, thereby reduce system to power control and synchronous requirement, the reduction system realizes complexity.

Above-mentioned purpose of the present invention is achieved in that a kind of signal creating method of non-interference quasi-synchronous CDMA communication system, may further comprise the steps:

From having zero correlation section length Z _CZSpread spectrum sequence code group in select spread spectrum code word as spreading code;

Utilize selected spread spectrum code word that the initial data of input is carried out band spectrum modulation processing, generate modulated spread spectrum signal thus;

Wherein, described spread spectrum sequence code group is best autocorrelation sequence and the T=2 of L=m (2k+1) by length ⁿRank Hadamard matrix construction forms, m＞2 wherein, k 〉=0.

In the signal creating method of non-interference quasi-synchronous CDMA communication system of the present invention, the auto-correlation function of arbitrary sequence has zero correlation block in zero displacement both sides in the described spread spectrum sequence code group.

In the signal creating method of non-interference quasi-synchronous CDMA communication system of the present invention, arbitrary cross-correlation function to sequence has zero correlation block in the zero displacement both sides that comprises zero displacement in the described spread spectrum sequence code group.

In the signal creating method of non-interference quasi-synchronous CDMA communication system of the present invention, in order to eliminate the influence of correlation function aperiodic, can be at the head and the tail two ends of described modulated spread spectrum signal supplementary protection chip.

The head and the tail two ends additional protection number of chips G of described modulated spread spectrum signal gets and is not more than zero correlation section length Z in the spread spectrum sequence code group _CZArbitrary value.

Wherein, when relative time delay between signal was within the supplementary protection chip lengths, the spread spectrum code word of described spread spectrum sequence code group was a quadrature.

In the signal creating method of non-interference quasi-synchronous CDMA communication system of the present invention, described spread spectrum sequence code group has m * T spread spectrum code word, m＞2 wherein, T=2 ⁿEach described spread spectrum code word has L * T chip, and wherein L is the length of described best autocorrelation sequence, and T is a Hadamard order of matrix number.

Wherein, above-mentioned L * T chip is by ± 1 or 0 chip of forming.

Wherein, the zero correlation section length of described spread spectrum sequence code group

In quasi-synchronous CDMA communication system, do not need the synchronous of very strictness between system base-station and each mobile subscriber, thereby realize simple.This system is that near the cross-correlation function value of in the synchronous error scope (zero time delay) is as far as possible little to the requirement of employing spread spectrum sequence code group correlation properties.In addition, because the wireless multipath transmission that mobile environment exists, system also requires near the auto-correlation function value of frequency expansion sequence sign indicating number zero time delay as far as possible little.Therefore, the above-mentioned generation method with spread spectrum sequence code group of zero correlation block that the present invention proposes is for realizing that in quasi-synchronous CDMA communication system noiseless transmission provides a kind of effective means.

Beneficial effect of the present invention is: maximum synchronous error of system and channel maximum multipath delay spread can realize noiseless transmission within the scope of defined the time.The parameter of spread spectrum sequence code group and system effectiveness can be adjusted in real time according to practical factor, choose flexibly.Reduced code division multiple address communication system to power control and synchronous requirement, reduced system and realized complexity.

The present invention is described in detail below in conjunction with accompanying drawing.

Description of drawings

Fig. 1 is the spread spectrum sequence code group example ZCZ-(84,28,3) with zero correlation block of the present invention;

Fig. 2 is periodic auto-correlation function figure of the present invention (is example with sequence among Fig. 1 1);

Fig. 3 is periodic auto-correlation function figure of the present invention (is example with sequence among Fig. 1 2);

Fig. 4 is periodic cross-correlation functional arrangement of the present invention (is example with sequence 2 with sequence among Fig. 1 1);

Fig. 5 is the signal format figure of the modulated spread spectrum signal of direct sequence CDMA communication system;

Fig. 6 is the modulated spread spectrum signal format chart of each code element correspondence among the present invention;

Fig. 7 is the signal transmission schematic diagram of cellular CDMA communication system down link;

Fig. 8 is the signal transmission schematic diagram of cellular CDMA communication system up link.

Embodiment

Zero correlation block spread spectrum sequence code group proposed by the invention, the best autocorrelation sequence a and the T rank Hadamard matrix H that are equaled L by the cycle generate as follows, L=m (2k+1) wherein, m＞2, k 〉=0, T=2 ⁿ

1. calculate s=T ^-1(mod 2k+1), structure initial vector e ₀=(e _0,1, e _0,2..., e _{0, T-1}), e wherein _{0, t}=st (mod L), 0≤t＜T.

2. construct one group of vector e _i=(e _{I, 1}, e _{I, 2}..., e _{I, T-1}), 0≤i＜m, wherein e _{I, t}=e _{0, t}+ i (2k+1) (mod L), 0≤t＜T, and be arranged as with matrix form

$E=\left[\begin{array}{cccc}{e}_{0,0}& e_{\mathrm{0,1}}& L& e_{0,T-1}\\ e_{\mathrm{1,0}}& e_{\mathrm{1,1}}& L& e_{1,T-1}\\ M& M& M& M\\ e_{m-\mathrm{1,0}}& e_{m-\mathrm{1,1}}& L& e_{m-1,T-1}\end{array}\right]$

Element to same row among the matrix E is done suitable displacement, does not change the position of row, obtains following matrix

$F=\left[\begin{array}{cccc}{f}_{\mathrm{0,0}}& f_{\mathrm{0,1}}& \mathrm{<figure-callout\; id="0"\; label="L\; f"\; filenames="A20071013018300121.png,A20071013018300131.png"\; state="\{\{state\}\}">L</figure-callout>}& f_{}{}_{0,T-1}\\ f_{\mathrm{1,0}}& {\mathrm{<figure-callout\; id="1"\; label="f"\; filenames="A20071013018300131.png,A20071013018300141.png"\; state="\{\{state\}\}">f</figure-callout>}}_{\mathrm{1,1}}& \mathrm{<figure-callout\; id="1"\; label="L\; f"\; filenames="A20071013018300131.png,A20071013018300141.png"\; state="\{\{state\}\}">L</figure-callout>}& f_{}{}_{1,T-1}\\ M& M& M& M\\ f_{m-\mathrm{1,0}}& f_{m-\mathrm{1,1}}& L& f_{m-1,T-1}\end{array}\right]$

All row vector 0≤f of this matrix _i＜m is discontented with sufficient following conditions,

$f_{j,t}=\left\{\begin{array}{c}{\mathrm{\&tau;}}_1+f_{i,t+{\mathrm{\&tau;}}_2}\left(\mathrm{mod}L\right),0\&le;t<T-{\mathrm{\&tau;}}_2\\ {\mathrm{\&tau;}}_1+f_{i,t+{\mathrm{\&tau;}}_2-T}+1\left(\mathrm{mod}L\right),T-{\mathrm{\&tau;}}_2\&le;t<T\end{array}\right.---\left(1\right)$

0≤τ wherein ₁＜L and ((0≤τ ₂＜T, i ≠ j) or (0≤τ ₂＜T, i=j)).

3. according to each row vector 0≤f of best autocorrelation sequence a and matrix F _i＜m, structural matrix

$U_i=\left[\begin{array}{cccc}{a}_{0+f_{i,0}}& a_{0+f_{i,1}}& L& a_{0+f_{i,T-1}}\\ a_{1+f_{i,0}}& a_{1+f_{i,1}}& L& a_{1+f_{i,T-1}}\\ M& M& M& M\\ a_{L-1+f_{i,0}}& a_{L-1+f_{i,1}}& L& a_{L-1+f_{i,T-1}}\end{array}\right]$

Add operation all is mould L computing in the subscript.Like this, just obtain m L * T matrix.

4. utilize the vectorial h of row of Hadamard matrix H _jMatrix U with last surface construction _iStructural matrix

$U_i^j=h_{j}e{U}_i,\mathrm{0,0}\&le;j<T,0\&le;i<m$

Here,

$h_{j}e{U}_i=\left[\begin{array}{cccc}{h}_{j,0}{a}_{0+f_{i,0}}& h_{j,1}{a}_{0+f_{i,1}}& L& h_{j,T-1}{a}_{0+f_{i,T-1}}\\ h_{j,0}{a}_{1+f_{i,0}}& h_{j,1}{a}_{1+f_{i,1}}& L& h_{j,T-1}{a}_{1+f_{i,T-1}}\\ M& M& M& M\\ h_{j,0}{a}_{L-1+f_{i,0}}& h_{j,1}{a}_{L-1+f_{i,1}}& L& h_{j,T-1}{a}_{L-1+f_{i,T-1}}\end{array}\right]$

5. with matrix u _i ^jIn element read line by line, the structure cycle is the sequence sets of LT $S=\left\{u_i^j\right|0\&le;i<m,0\&le;j<T\},$ Promptly

$u_i^j=(h_{j,0}{a}_{0+f_{i,0}},h_{j,1}{a}_{0+f_{i,1}},L,h_{j,T-1}{a}_{0+f_{i,T-1}},h_{j,0}{a}_{1+f_{i,0}},h_{j,T-1}{a}_{1+f_{i,T-1}},L{h}_{j,T-1}{a}_{L-1+f_{i,T-1}}),$

Thereby obtain a ZCZ-(LT, mT, 2k+1) sequence sets.

The sequence sets S that is generated has mT sequence (each sequence is a spread spectrum code word that is used for spread-spectrum), the absolute value of the correlation function between these sequences (removing the auto-correlation function main peak) is at interval (2k-1, be zero 2k+1). or rather, except auto-correlation function is the LT in zero displacement place, all the other are zero. thereby, by suitable selection parameter T, L, m, k just can obtain the zero correlation sequence sets of actual needs.

For example, given L=21, m=3,2k+1=7, T=4, then s=T ^-1=2 (mod 2k+1).Can be with the one group of vector e that obtains _i, 0≤i＜m is arranged as with matrix form:

$E=\left[\begin{array}{cccc}0& 1& 2& 3\\ 3& 4& 5& 6\\ 6& 7& 8& 9\\ 9& 10& 11& 12\\ 12& 13& 14& 15\\ 15& 16& 17& 18\\ 18& 19& 20& 0\end{array}\right]$

Element in the same row among the matrix E is done suitable displacement, obtain matrix

$F=\left[\begin{array}{cccc}0& 1& 2& 6\\ 3& 4& 20& 3\\ 6& 7& 17& 0\\ 9& 10& 14& 18\\ 12& 13& 11& 15\\ 15& 16& 8& 12\\ 18& 19& 5& 9\end{array}\right]$

The capable vector of this matrix does not satisfy formula (1).The cycle of choosing be the best autocorrelation sequence a=of 21 ternary (++-0+0+-+++++--0-+00) and 4 rank Hadamard matrixes

$H=\left[\begin{array}{cccc}1& 1& 1& 1\\ 1& -1& 1& -1\\ 1& 1& -1& -1\\ 1& -1& -1& 1\end{array}\right]$

So set by step 3,4 and step 5 just can obtain with ZCZ-(84,28, a 3) sequence sets as shown in Figure 1.

The signal creating method of non-interference quasi-synchronous CDMA communication system of the present invention has a zero correlation section length Z based on above-mentioned _CZSpread spectrum sequence code group, may further comprise the steps:

From having zero correlation section length Z _CZSpread spectrum sequence code group in select spread spectrum code word as spreading code;

Utilize selected spread spectrum code word that the initial data of input is carried out band spectrum modulation processing, generate modulated spread spectrum signal thus;

Wherein, described spread spectrum sequence code group is best autocorrelation sequence and the T=2 of L=m (2k+1) by length ⁿRank Hadamard matrix construction forms, m＞2 wherein, k 〉=0.

For quasi-synchronous CDMA communication system of the present invention, in order to make full use of the excellent specific property of above-mentioned spreading code, modulated spread spectrum signal is made up of with the product of corresponding frequency expansion sequence sign indicating number and the supplementary protection chip at head and the tail two ends each signal element.The supplementary protection number of chips (G) at this modulated spread spectrum signal head and the tail two ends is desirable to be not more than zero correlation section length (Z in the spread spectrum sequence code group _CZ) arbitrary value.Owing to adopted this special spread spectrum modulation signal format, if between signal relative time delay within the supplementary protection chip lengths, remain quadrature between each frequency expansion sequence sign indicating number, thereby can eliminate because multipath effect or multiple access insert the interference that is brought.

Referring to Fig. 1, it is a ZCZ-who is example with 28 frequency expansion sequences (84,28, a 3) sequence code character, can use for 16 users.Have 28 spread spectrum code words, each spread spectrum code word is made up of 84 ± 1 or 0 (chip), the zero correlation section length Z of its spread spectrum sequence code group _CZ=84/28=3.

Referring to Fig. 2 and Fig. 3, they are respectively the periodic auto-correlation function figure of sequence 1 and sequence 2 among Fig. 1.Other sequence has the periodic auto-correlation function of all fours, and promptly time delay is ± 1, ± 2 o'clock, and its periodic auto-correlation function value is zero.

Referring to Fig. 4, it is the periodic cross-correlation functional arrangement of sequence 1 and sequence 2 among Fig. 1.Other arbitrary sequence is to having the periodic cross-correlation function of all fours, and promptly time delay is 0, ± 1, and ± 2 o'clock, its periodic cross-correlation functional value was zero.

Any spread spectrum sequence code group that other has zero correlation block of the present invention all has the periodic auto-correlation function and the periodic cross-correlation function of all fours.Be characterized in:

The periodic auto-correlation function of arbitrary sequence has zero correlation block in zero displacement both sides, and arbitrary periodic cross-correlation function to sequence has zero correlation block in zero displacement both sides (comprising zero displacement) in the spread spectrum sequence code group.

Sequence length N, sequence number M, zero correlation section length Z in the spread spectrum sequence code group _CZSatisfy and concern MZ _CZ=N.

Referring to Fig. 5, it is the modulated spread spectrum signal format chart of conventional direct sequence CDMA communication system.Wherein received signal R (t) is by useful signal V _S(t) and interference signal V _X(t) form, they are to modulate the A that corresponding ternary information bit obtains ,-A, B ,-B by the spread-spectrum signal of sequence A and B correspondence respectively.Since the not exclusively synchronous or multipath effect of system, V _S(t) and V _X(t) has τ in relative time delay between.Suppose that receiving terminal can make despread signal V by conventional method _D(t) with desired transmitting terminal signal V _S(t) synchronous, but V _D(t) and V _X(t) be asynchronous in itself, thereby the correlation function nonzero value will bring inevitable interference aperiodic in the demodulating process.

For overcoming by the interference that causes relative time delay, system works is in the accurate method of synchronization, and promptly by the base station pilot signal transmitted, the transmission that makes each travelling carriage in the sub-district is controlled at the transmission of each travelling carriage in certain scope as far as possible synchronously relative time delay.In order to eliminate the influence of correlation function aperiodic, can in modulated spread spectrum signal, add the protection chip.

Referring to Fig. 6, it is the modulated spread spectrum signal format chart of each code element correspondence.A wherein _CLength be NT _C(T _CBe chip period), take from ZCZ-(N, M, Z by one _CZ) spread-spectrum signal of sequence correspondence of sequence code character forms, as this user's signature signal.A _HWith A _TLength be GT _C, be respectively A _CG the chip at middle head and the tail two ends is as the protection chip.

The supplementary protection number of chips (G) at head and the tail two ends is desirable in the described modulated spread spectrum signal is not more than zero correlation section length (Z in the spread spectrum sequence code group _CZ) arbitrary value, when relative time delay between signal was within the supplementary protection chip lengths, described frequency expansion sequence sign indicating number was a quadrature.

Referring to Fig. 7, it is the signal transmission schematic diagram of cellular CDMA communication system down link, all signals from the base station to the travelling carriage synchronous transmission, so useful signal V _S(t) and interference signal V _X(t) arrive receiving terminal simultaneously.But, since the existence of multipath effect, V _S(t) and V _X(t) the signal V behind time-delay τ ' _S' (t) and V _X' (t) just become interference in the system.As long as τ ' is no more than GT _C, system interference is only relevant with periodic correlation function.If adopt ZCZ-(N, M, Z _CZ) the sequence code character is as each user's signature address sequence, and satisfy G≤Z _CZ, system realizes noiseless transmission.

Referring to Fig. 8, it is the signal transmission schematic diagram of cellular CDMA communication system up link, because travelling carriage can not be accomplished fully synchronously interference signal V to the signal of base station transmits _X(t) with useful signal V _S(t) non-vanishing their cross correlation has just caused the interference in the system between.But because system works is in the accurate method of synchronization, the transmission τ in relative time delay of each travelling carriage in the sub-district " is controlled in certain scope.As long as τ " is no more than GT _C, system interference is only relevant with periodic correlation function.If adopt ZCZ-(N, M, Z _CZ) the sequence code character is as each user's signature address sequence, and satisfy G≤Z _CZ, system realizes noiseless transmission.

Therefore; have the signature address sequence of the spread spectrum sequence code group of zero correlation block as each user by use; and, just can realize the noiseless transmission of quasi-synchronous CDMA communication system up link and down link at the suitable protection chip of modulated spread spectrum signal adding.

Claims (10)

1. the signal creating method of a non-interference quasi-synchronous CDMA communication system is characterized in that may further comprise the steps:

From having zero correlation section length Z _CZSpread spectrum sequence code group in select spread spectrum code word as spreading code;

Utilize selected spread spectrum code word that the initial data of input is carried out band spectrum modulation processing, generate modulated spread spectrum signal thus;

Wherein, described spread spectrum sequence code group is best autocorrelation sequence and the T=2 of L=m (2k+1) by length ⁿRank Hadamard matrix construction forms, m＞2 wherein, k 〉=0.

2. according to the signal creating method of right 1 described non-interference quasi-synchronous CDMA communication system, it is characterized in that: the auto-correlation function of arbitrary sequence has zero correlation block in zero displacement both sides in the described spread spectrum sequence code group.

3. according to the signal creating method of right 1 described non-interference quasi-synchronous CDMA communication system, it is characterized in that: arbitrary cross-correlation function to sequence has zero correlation block in the zero displacement both sides that comprises zero displacement in the spread spectrum sequence code group.

4. according to the signal creating method of right 1 described non-interference quasi-synchronous CDMA communication system, it is characterized in that also comprising: at the head and the tail two ends of described modulated spread spectrum signal supplementary protection chip.

5. according to the signal creating method of right 4 described non-interference quasi-synchronous CDMA communication systems, it is characterized in that: head and the tail two ends additional protection number of chips G gets and is not more than zero correlation section length Z in the spread spectrum sequence code group in the described modulated spread spectrum signal _CZArbitrary value.

6. according to the signal creating method of right 5 described non-interference quasi-synchronous CDMA communication systems, it is characterized in that: when relative time delay between signal was within the supplementary protection chip lengths, the spread spectrum code word of described spread spectrum sequence code group was a quadrature.

7. according to the signal creating method of right 1 described non-interference quasi-synchronous CDMA communication system, it is characterized in that: described spread spectrum sequence code group has m * T spread spectrum code word, m＞2 wherein, T=2 ⁿ

8. according to the signal creating method of right 1 or 7 described non-interference quasi-synchronous CDMA communication systems, it is characterized in that: each spread spectrum code word has L * T chip, and wherein L is the length of described best autocorrelation sequence, and T is a Hadamard order of matrix number.

9. according to the signal creating method of right 8 described non-interference quasi-synchronous CDMA communication systems, it is characterized in that: described L * T chip is by ± 1 or 0 chip of forming.

10, according to the signal creating method of right 7 or 8 described non-interference quasi-synchronous CDMA communication systems, it is characterized in that: the zero correlation section length of described spread spectrum sequence code group

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