CN102752067B - Method and device for forming two-dimensional optical orthogonal code with zero correlation window - Google Patents
Method and device for forming two-dimensional optical orthogonal code with zero correlation window Download PDFInfo
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Abstract
The invention relates to a method for forming a two-dimensional optical orthogonal code with a zero correlation window, and the method comprises following steps of constructing a first sequence with the zero correlation window; constructing a second sequence; and mapping the first sequence and the second sequence to form the two-dimensional optical orthogonal code with the zero correlation window. The invention also relates to a device for realizing the method. The method and the device for forming the two-dimensional optical orthogonal code with the zero correlation window have following beneficial effects that the two-dimensional orthogonal code is completely orthogonal, i.e. the autocorrelation limit of the code is zero, cross-correlation limit of the code is also zero, and thus the multi-address interference and beat noise can be completely eliminated, the near-far effect of a two-dimensional optical code division multiple access (OCDMA) system also can be eliminated; therefore, the two-dimensional OCDMA system with large capacity can be realized, and the two-dimensional OCDMA system can be applied to an optical access network, an optical local area network, an optical code mark switching network, an optical fiber sensor network and the like.
Description
Technical field
The present invention relates to optical communication field, more particularly, relate to a kind of formation method and the device with the two-dimensional optical orthogonal code of zero correlation window.
Background technology
Optical code division multiple access (Optical Code Division Multiple Access, is abbreviated as OCDMA) has the features such as broadband, safety and random instant access, is one of preferred plan of following high-speed local area network and Access Network.Divide by the degree of freedom and can be divided into one dimension OCDMA system and two-dimentional OCDMA system, the address code of two-dimentional OCDMA system is not only expanded in time domain, also expands on wavelength simultaneously, is called two-dimensional optical orthogonal code.Two-dimensional optical orthogonal code is generally on the basis of one dimension light address code, is obtained by expansion wavelength channel.
At present, many scholars both domestic and external have constructed multiclass two dimension OCDMA address code.Based on prime codes (Prime code), Tancevski.L etc. construct PC/PC and EQC/PC, and the auto-correlation of PC/PC code is 0, and the auto-correlation that cross-correlation is limited to 1, EQC/PC is 0, and cross-correlation is limited to 2.Wan Shengpeng etc., based on prime codes and light orthogonal code, construct PC/OOC code, and its auto-correlation is 0, and cross-correlation is limited to 1.Zhou Xiuli etc. are based on RS code, and construct multiple length multi-wavelength RS code, its auto-correlation is 0, and cross-correlation is limited to 1.Yin Hongxi etc. construct two-dimentional OCFHC/OOC code and two dimension becomes repeated code, and cross-correlation is limited to 1.Li Chuanqi etc. construct two-dimentional QPC code, and cross-correlation is limited to 1.Lee and Seo utilizes two different one dimension OOC respectively in time domain and frequency domain expansion, and the code of the two-dimensional optical orthogonal code of structure is heavily 3, and cross-correlation is limited to 1.Kwong and Yang utilizes prime-hop sequence to control time domain and frequency domain, and the code length of the two-dimensional optical orthogonal code of structure is prime number, and cross-correlation limit equals 1.Kwong etc. adopt prime codes and cyclic sequence thereof to be frequency domain spread spectrum sequence, and one dimension OOC is time domain frequency expansion sequence, and number of wavelengths is the product of prime number, and the cross-correlation limit of two-dimensional optical orthogonal code equals 1.E.S.Shivaleela etc. utilize finite field directly to construct two-dimensional optical orthogonal code, and cross-correlation limit equals 1.Jen-Hao Tien and Yang etc. constructs the Quick Response Code that cross-correlation is limited to 2, adds cardinality, but adds the multi-access inference between user.S.Kim and K.Yu constructs three-dimensional light orthogonal code, and expand in time domain/frequency domain/spatial domain (or polarization territory) respectively, its cardinality increases greatly, but system realizes difficulty greatly, and relevant follow-up study is less.Also have both at home and abroad a lot of scholar to construct multiple Quick Response Code, but cross-correlation limit all equals 1 or be greater than 1, two-dimensional optical orthogonal code all cannot be completely orthogonal.
In two-dimentional OCDMA system, the noise affecting whole system performance mainly comprises multi-access inference and beat noise.Multi-access inference is caused by the non-orthogonal of code word, and beat noise is caused by a square characteristic for photodetector, and this depends on the orthogonality of code word equally.The two-dimensional optical orthogonal code constructed at present mainly contains: PC/PC, EQC/PC, PC/OOC, OOC/PC, OCFHC/OOC, EQC/OCS, PC/OCS, OOC/OCS etc., and all these code words are all not exclusively orthogonal, and namely the cross-correlation limit of code word is non-vanishing.
As mentioned above, the address code adopted due to current two-dimentional OCDMA system can not completely orthogonal (cross-correlation limit is minimum be 1), and namely the cross-correlation limit of code word is non-vanishing, and their cross correlation is undesirable, and therefore system exists serious multi-access inference and beat noise.Especially when concurrent user number is more, multi-access inference and beat noise become topmost noise, make the error rate of two-dimentional OCDMA system sharply increase, thus cause the access customer number of two-dimentional OCDMA to be restricted.Meanwhile, because two-dimensional address codes can not be completely orthogonal, there is near-far interference in two-dimentional OCDMA system, and this needs complicated power to control.Therefore, current two-dimentional OCDMA system is difficult to practical.
Summary of the invention
The technical problem to be solved in the present invention is, address above mentioned code for prior art can not be completely orthogonal, the defect that their cross correlation is undesirable, provides a kind of completely orthogonal, formation method with the two-dimensional optical orthogonal code of zero correlation window that their cross correlation is desirable and device.
The technical solution adopted for the present invention to solve the technical problems is: construct a kind of formation method with the two-dimensional optical orthogonal code of zero correlation window, comprise the steps:
A) there is the First ray of zero correlation zone; Described First ray is the binary sequence formed by 0,1; The Cycle Length of described First ray equals the code length of code word; The main peak of the auto-correlation function of described First ray equals the number of basic pulse; The submaximum value of the auto-correlation function of described First ray has 1,0 two values;
B) the second sequence is constructed; Described second sequence is a kind of frequency hop sequences, and all code words of described second sequence are isometric; The code length of described second sequence equals the pulse number of described First ray; The number of wavelengths of described second sequence is greater than the pulse number of First ray; In each code word of described second sequence, each wavelength is to once multiplex;
C) described First ray and described second sequence are mapped, then form the two-dimensional optical orthogonal code with zero correlation window; In described two-dimensional optical orthogonal code, each wavelength is extremely once multiplex in each code word; The described two-dimensional optical orthogonal code with zero correlation window is in arbitrary time shifting, and any two different code words have an overlapping wavelengths at the most.
Have in the formation method of the two-dimensional optical orthogonal code of zero correlation window of the present invention, described step C) in mapping be pulse with the corresponding element position of the wavelength control First ray corresponding to the wavelength sequence number represented by each code element content of the second sequence.
Having in the formation method of the two-dimensional optical orthogonal code of zero correlation window of the present invention, the code length N of described First ray, there is following relation: N >=m(m-1 in basic pulse number m, zero correlation section length Z)+2Z-1.
Have in the formation method of the two-dimensional optical orthogonal code of zero correlation window of the present invention, described steps A) comprise the steps: further
A1) the zero correlation section length Z of given pulse number m, sequence, the spacing δ of adjacent two pulses
t, set intermediate variable mal and initialize; Wherein, 1≤t≤m, and t is integer;
A2) by intermediate variable mal assignment to δ
t, perform steps A 3);
A3) judge whether to exist
or
in this way, mal value is from adding 1 and returning steps A 2); Otherwise, by mal value assignment to δ
t, perform steps A 4); Wherein, exist
in, 1≤i < j < t, 1≤i < m, 1≤j < m, 1≤t≤m, and i, j, t are integer; ?
in, 1≤i < j < r < t, 1≤i < m, 1≤j < m, 1≤r < m, 1≤t≤m, and i, j, r, t are integer;
A4) judge whether t is less than m, in this way, mal value, from adding 1, t from adding 1, performs steps A 2); Otherwise, perform steps A 5);
A5) δ is read
1, δ
2..., δ
mvalue and return.
Have in the formation method of the two-dimensional optical orthogonal code of zero correlation window of the present invention, described step B) comprise the steps: further
B1) number of wavelengths and the code length of the second sequence is obtained according to First ray;
B2) according to number of wavelengths and code length, the addition being number of wavelengths respectively by its mould obtains several second sequence of described wavelength of specifying, and the code length of described second sequence is the pulse number of described First ray.
Have in the formation method of the two-dimensional optical orthogonal code of zero correlation window of the present invention, described step C) comprise the steps: further
C1) each wavelength value corresponding to wavelength sequence number represented by code element content of the second sequence is obtained;
C2) basic pulse of each code element of First ray is made to answer the wavelength value corresponding to the wavelength sequence number represented by the code element content of position for the second sequence pair.
The invention still further relates to a kind of device realizing said method, comprising:
First ray structural unit: for there is the First ray of zero correlation zone; Described First ray is the binary sequence formed by 0,1; The Cycle Length of described First ray equals the code length of code word; The main peak of the auto-correlation function of described First ray equals the number of basic pulse; The submaximum value of the auto-correlation function of described First ray has 1,0 two values;
Second sequence structure unit: for constructing the second sequence; Described second sequence is a kind of frequency hop sequences, and all code words of described second sequence are isometric; The code length of described second sequence equals the pulse number of described First ray; The number of wavelengths of described second sequence is greater than the pulse number of First ray; In each code word of described second sequence, each wavelength is to once multiplex;
Light orthogonal code forming unit: for described First ray and described second sequence being mapped, then form the two-dimensional optical orthogonal code with zero correlation window; In described two-dimensional optical orthogonal code, each wavelength is extremely once multiplex in each code word; The described two-dimensional optical orthogonal code with zero correlation window is in arbitrary time shifting, and any two different code words have an overlapping wavelengths at the most.
In device of the present invention, described First ray structural unit comprises further:
Setting parameter and initialize module: for the zero correlation section length Z of given pulse number m, sequence, the spacing δ of adjacent two pulses
t, set intermediate variable mal and initialize; Wherein, 1≤t≤m, and t is integer;
Pulse spacing assignment module: for by intermediate variable mal assignment to δ
t;
Pulse spacing judge module: exist for judging whether
or
in this way, mal value is from adding 1 assignment to δ
tand repeat above-mentioned judgement; Otherwise, by mal value assignment to δ
t; Wherein, exist
in, 1≤i < j < t, 1≤i < m, 1≤j < m, 1≤t≤m, and i, j, t are integer; ?
in, 1≤i < j < r < t, 1≤i < m, 1≤j < m, 1≤r < m, 1≤t≤m, and i, j, r, t are integer;
Pulse spacing sequence number judge module: for judging whether t is less than m, in this way, mal value is from adding 1, t from adding 1;
Pulse spacing obtains module: after terminating to judge, read δ
1, δ
2..., δ
mvalue and return.
In device of the present invention, described second sequence structure unit comprises further:
Parameter acquisition module: for obtaining number of wavelengths and the code length of the second sequence according to First ray;
Modular arithmetic module: for according to number of wavelengths and code length, the addition being number of wavelengths respectively by its mould obtains several second sequence of described wavelength of specifying, and the code length of described second sequence is the pulse number of described First ray.
In device of the present invention, described light orthogonal code forming unit comprises further:
Wavelength obtains module: for obtaining the wavelength value corresponding to the wavelength sequence number represented by each code element content of the second sequence;
Pulse control module: answer the wavelength value corresponding to the wavelength sequence number represented by the code element content of position for the second sequence pair for making the basic pulse of each code element of First ray.
Implement formation method and the device with the two-dimensional optical orthogonal code of zero correlation window of the present invention, there is following beneficial effect: owing to First ray and the second sequence being mapped, form a kind of two-dimensional optical orthogonal code with zero correlation window, in certain reference time delay, as long as the delay namely between user is in zero correlation block, this two-dimensional optical orthogonal code is completely orthogonal, namely the auto-correlation of code word is zero, the cross-correlation limit of code word is also zero, this will eliminate multi-access inference and beat noise completely, also the near-far interference of two-dimentional OCDMA system can be eliminated, therefore, jumbo two-dimentional OCDMA system can be realized, be applied to optical access network, optical local area network, light code labeling switching network, Fibre Optical Sensor net etc.
Accompanying drawing explanation
Fig. 1 is in the present invention's formation method with the two-dimensional optical orthogonal code of zero correlation window and device embodiment
The flow chart block diagram of method;
Fig. 2 is the particular flow sheet of method in described embodiment;
Fig. 3 is the structural representation of device in described embodiment;
Fig. 4 is the structural representation of First ray structural unit in described embodiment.
Embodiment
Can understand for the ease of those of ordinary skill in the art and implement the present invention, below in conjunction with accompanying drawing, embodiments of the present invention is further illustrated.
In the formation method in the present invention with the two-dimensional optical orthogonal code of zero correlation window and device embodiment, as shown in Figure 1, in FIG, its method comprises the steps: the flow chart block diagram of its method
Step S001 there is the First ray of zero correlation zone: in this step, due to will basic sequence be constructed, and this basic sequence will have zero correlation zone, consider large regions (Large area, being abbreviated as LA) sequence is not only zero-correlation zone sequence under cycle relevance, the length in its cycle equals the code length of code word, and is the zero-correlation zone sequence under relevance aperiodic.Therefore, this First ray has selected basic sequence or its basic sequence improved of LA sequence.In the present embodiment, First ray has selected the basic sequence of LA sequence, and certainly, in other cases, First ray also can select its basic sequence improved of LA sequence.Specifically, LA basic sequence is the binary sequence formed by 0,1, is a kind of zero correlation sequences.LA is generally expressed as LA (N, m, Z), and N represents code length, and m represents basic pulse number, and Z represents zero correlation section length.If X
j(j=0,1 ..., N-1) be the basic sequence of LA (N, m, Z), then the periodic auto-correlation function of LA basic sequence is
Wherein, l represents relative time delay,
for the addition of mould N.By above-mentioned expression formula, can show that the main peak of the auto-correlation function of this LA basic sequence equals the number of basic pulse; The submaximum value of auto-correlation function only has 1,0 two kinds of situations; There is a zero correlation block in auto-correlation.
In the present embodiment, the pulse number of given basic sequence is m, and the zero correlation section length of sequence is the basic sequence s of Z, LA sequence is by setting each pulse spacing δ
twith the relation of zero correlation section length Z, the pulse spacing calculating this sequence constructs.About the setting of basic pulse, normalization amplitude and width in the present embodiment, is selected to be the basic pulse of 1; Here, it is pointed out that basic pulse interval δ
tbe not less than zero correlation section length Z, between the two without absolute mathematical relationship, but there is theory lower-bound, as N>=m(m-1)+2Z-1.About how specifically setting each pulse spacing δ in the present embodiment
twith the relation of zero correlation section length Z, and how to calculate the pulse spacing δ of this sequence
tand then construct basic sequence s, refer to Fig. 2, also can be described after a while.
Step S002 constructs the second sequence: in this step, and second sequence that construct is a kind of frequency hop sequences; Single reclose sequence (One-coincidence sequence, be abbreviated as OCS) be the pseudo random sequence that a string adjacent element has specific range, all code words are isometric, its auto-correlation is 0, that is, phase co-wavelength in same code word occurs at most once, i.e., in each code word of the second sequence, each wavelength is to once multiplex.OCS code is in arbitrary time shifting, and any two different code words have at most an overlapping wavelengths.Therefore, in the present embodiment, the second sequence has selected OCS sequence, and certainly, in other cases, the second sequence also can select other frequency hop sequences.It should be noted that, in the present embodiment, the code length of the second selected sequence equals the pulse number of First ray, and the number of wavelengths of the second sequence is greater than the pulse number of First ray.About how specifically to construct the second sequence, refer to Fig. 2, also can be described after a while.
First ray and the second sequence map by step S003, form two-dimensional optical orthogonal code: in this step, two-dimensional optical orthogonal code has zero correlation zone, each wavelength is extremely once multiplex in each code word, the above-mentioned two-dimensional optical orthogonal code with zero correlation window is in arbitrary time shifting, and any two different code words have an overlapping wavelengths at the most.The above-mentioned two-dimensional optical orthogonal code with zero correlation window comprises the First ray and the second sequence with zero correlation zone, in order to obtain the above-mentioned two-dimensional optical orthogonal code with zero correlation window, First ray and the second sequence is needed to map, for the present embodiment, the basic sequence of LA and frequency hopping code OCS are mapped exactly, said mapping is the pulse with the corresponding element position of the wavelength control First ray corresponding to the wavelength sequence number represented by each code element content of the second sequence.Map to be formed the two-dimensional optical orthogonal code with zero correlation window about how to carry out, refer to Fig. 2, also can be described after a while.
Fig. 2 gives the particular flow sheet of method in the present embodiment.In fig. 2, the idiographic flow of its method comprises the following steps:
Step S101 setup parameter, to intermediate variable initialize: in the present embodiment, basic sequence s passes through program, obtain according to certain algorithm search, have many algorithms can obtain this basic sequence, in the present embodiment, only provide wherein a kind of building method, certainly, in other cases, also this basic sequence can be constructed with additive method.In this step, the pulse number of given basic sequence is m, and the zero correlation section length of sequence is Z, supposes that the position of m pulse respectively is X
1, X
2..., X
m, and adjacent two interpulse distances (i.e. pulse spacing) are δ
i=X
i+1-X
i, wherein, 1≤i<m, and i is integer, δ
m=N-X
m, here, N represents code length.In this step, pulse spacing δ is set
1=Z, δ
2=Z+1, δ
3=Z+2, definition intermediate variable mal=Z+3; In other words, pulse spacing δ is namely set
1, δ
2, δ
3with the relation of zero correlation section length Z, and the relation of the initial value of intermediate variable mal and zero correlation section length Z.
Step S102 by intermediate variable assignment to pulse spacing δ
t: in this step, by the intermediate variable mal assignment in above-mentioned steps S101 to pulse spacing δ
t, wherein, 1≤t≤m, and t is integer.Such as: due to pulse spacing δ in above-mentioned steps S101
1, δ
2, δ
3set initial value respectively, in this step, by the value assignment of intermediate variable mal=Z+3 to δ
4; If do not set δ in above-mentioned steps S101
1, δ
2, δ
3initial value, then direct by the initial value assignment of intermediate variable mal to δ
1, in this case, the judgement of step S103 just need not be carried out.Certainly, by intermediate variable assignment to pulse spacing δ
ttime, t(pulse spacing sequence number) value be change, span is 1≤t≤m, and t is integer.
Step S 103 exists
or
in this step, judge whether to exist
or
if existed, directly perform step S104; Otherwise, perform step S105; Wherein, exist
in, 1≤i < j < t, 1≤i < m, 1≤j < m, 1≤t≤m, and i, j, t are integer; ?
in, 1≤i < j < r < t, 1≤i < m, 1≤j < m, 1≤r < m, 1≤t≤m, and i, j, r, t are integer.Such as: when t gets 4, judge whether to exist
or
if existed, directly perform step S104; Otherwise, perform step S105; Wherein, exist
in, 1≤i < j < 4,1≤i < m, 1≤j < m, 1≤t≤m, and i, j, t are integer; ?
in, 1≤i < j < r < 4,1≤i < m, 1≤j < m, 1≤r < m, 1≤t≤m, and i, j, r, t are integer.
Step S104 intermediate variable is from adding 1: when the judged result in step S103 is for being, then will perform this step, and namely intermediate variable mal is from adding 1, it is worth mentioning that, after performing this step, will return and perform step S102, after also namely mal adds 1 certainly, assignment is to pulse spacing δ
t, the next round then continuing to repeat step S103 judges, until search is not existed the mal of equal situation.
Step S105 obtains a pulse spacing: in this step, when the judged result of step S103 is no, then performs this step, namely obtains a pulse spacing δ
t, mal value is now pulse spacing δ
tvalue.Such as: when t gets 4, then a pulse spacing δ is obtained
4, mal value is now pulse spacing δ
4value.
Does step S106 obtain whole pulse spacing? in this step, judge whether to obtain whole pulse spacing (m pulse spacing), be in fact equivalent to judge whether t is less than m, in this way, namely t is less than m, does not namely obtain whole pulse spacing, then perform step S107; Otherwise, perform step S108.
Step S107 intermediate variable is from adding 1, t is from adding 1: when above-mentioned steps S106 judged result is not for obtaining whole pulse spacing, namely when t is less than m, then perform this step, intermediate variable mal is from adding 1, t is from adding 1, it is worth mentioning that, after performing this step, return and perform step S102, then the next round continuing to repeat step S103 judges, until search obtains whole pulse spacing.
Step S108 reads whole pulse spacing, obtains First ray: when above-mentioned steps S106 judged result is for obtaining whole pulse spacing (m pulse spacing), then performs this step, read whole m pulse spacing δ
1, δ
2..., δ
m, thus obtain basic sequence s, be also First ray.
Simply illustrate providing one to above-mentioned steps S101 to S108 about the flow process of search utility below: the two-dimensional array first defining a m × m, (0,0) individual element value is set as δ
1, (1,0), (1,1) individual element value are set as δ respectively
1+ δ
2, δ
2, (2,0), (2,1), (2,2) individual element value are set as δ
1+ δ
2+ δ
3, δ
2+ δ
3, δ
3, make (3,3) individual element value be mal, judge that whether mal value exists equal situation with the element of assignment above, if existed, making mal value from adding 1, repeating above judgement, if there is no then set element (3,0), (3,1), (3,2) value be δ
1+ δ
2+ δ
3+ mal, δ
2+ δ
3+ mal, δ
3+ mal, then judge whether element (3,0), (3,1), (3,2) have equal situation with element value above, if had, make mal after adding 1 again assignment to (3,3), then repeat above judgement, if do not had, mal value is now assigned to δ
4, mal value is from adding 1.The rest may be inferred, as search δ
ttime, here, 4<t<m, and t is integer, make (the t of array, t) individual element value is mal, judge (t, t) whether there is equal situation with element above, exist then make mal after add 1 again assignment to (t, t), rejudge, do not exist and then make (t, 0), (t, 1), (t, t-1) value is respectively (t-1, 0)+mal, (t-1, 1)+mal, (t-1, t-1)+mal, judge whether these element values have equal situation with the element of assignment before, having, making mal from adding 1 rear assignment to element (t, t), do not have, mal value is now δ
tvalue, mal from adding 1, then searches for next δ, until search whole m δ, the element on the diagonal now in array is δ
1, δ
2..., δ
m.In the present embodiment, basic pulse number m=8, zero correlation section length Z=16, according to each pulse spacing of above-mentioned setting and the relation of zero correlation section length Z, calculate corresponding basic pulse interval δ by corresponding
t{ δ
t, t=1,2 ..., 8}={16,17,18,20,19,22,23,21}, thus obtain basic sequence (i.e. First ray) and be:
Or be expressed as by pulse position: s={0,16,33,51,71,90,112,135}.Certainly, in other cases, basic pulse number m also can select other positive integers, and the basic sequence s of its correspondence can obtain as stated above.
Step S109 obtains number of wavelengths and code length according to First ray: in the present embodiment, the code length of the second sequence equals the pulse number of First ray, in this step, pulse number according to First ray obtains the code length of the second sequence, it should be noted that, the number of wavelengths of the second sequence can set, but will satisfy condition: the number of wavelengths of the second sequence is greater than the pulse number of First ray.
Step S110 carries out the addition that mould is number of wavelengths, obtain the second sequence: in this step, according to the number of wavelengths obtained in step S109 and code length, respectively by several second sequence of wavelength that its mould addition that is number of wavelengths obtains specifying, the code length of this second sequence is the pulse number of above-mentioned First ray.It is worth mentioning that, the building method of the second sequence has multiple, in the present embodiment, only provides a kind of wherein method, certainly, in other cases, also can obtain the second sequence with additive method.In the present embodiment, according to number of wavelengths and code length, obtain OCS code (i.e. the second sequence) by program search.In the present embodiment, setted wavelength number is 13, and the pulse number according to First ray is 8, and the code length obtaining the second sequence is 8, is the addition of number of wavelengths 13 by mould, in fact namely obtains OCS code (the second sequence) by program search to be:
Wherein,
for the addition of mould 13, so have 13 OCS codes, { H
0, H
1..., H
12.Certainly, in other cases, number of wavelengths and code length can get other positive integers according to the pulse number change of First ray, and its corresponding OCS code (the second sequence) can obtain as stated above.
Step S111 obtains wavelength value corresponding to the wavelength sequence number of the second sequence code element content representation: in this step, obtains each wavelength value corresponding to wavelength sequence number represented by code element content of the second sequence; Such as: select any one OCS code word, as H
0={ 3,8,1,5,2,10,4,0}, then the wavelength value corresponding to each code element is: { λ
3, λ
8, λ
1, λ
5, λ
2, λ
10, λ
4, λ
0.
Step S112 second sequence code element content corresponding wavelength value controls First ray, obtain two-dimensional optical orthogonal code: in this step, make the basic pulse of each code element of First ray answer the wavelength value corresponding to the wavelength sequence number represented by the code element content of position for the second sequence pair.In the present embodiment, for First ray
or s={0,16,33,51,71,90,112,135}, choose the arbitrary code word H of the second sequence
0={ wavelength value { the λ corresponding to each code element of 3,8,1,5,2,10,4,0}
3, λ
8, λ
1, λ
5, λ
2, λ
10, λ
4, λ
0, make the basic pulse of each code element of First ray answer the wavelength value corresponding to the wavelength sequence number represented by the code element content of position, even if First ray (basic sequence of LA sequence) is a Quick Response Code for the second sequence pair:
or be expressed as: { (0,3), (16,8), (33,1), (51,5), (71,2), (90,10), (112,4), (135,0) }, wherein (x, y) indicating impulse position is x, and corresponding wavelength is y.In the present embodiment, this has the two-dimensional optical orthogonal code set C of zero correlation window
krepresent, wherein, k=0,1,2 ..., 12, here, the value of k is relevant with the number of wavelengths of OCS code (the second sequence), as: number of wavelengths is n, then k=0,1,2 ..., n-1.In the present embodiment, get the LA basic sequence (First ray) of basic pulse number m=8:
or s={0,16,33,51,71,90,112,135}, to get number of wavelengths be 13, code length N be 8 OCS code (the second sequence):
K=0,1 ..., 12, wherein,
for the addition of mould 13, so have 13 OCS codes.Different OCS code words (the second sequence) and LA basic sequence (First ray) map, and can form a different Quick Response Code, therefore, have 13 Quick Response Codes:
K=0,1 ..., 12, here,
represent the addition of mould 13.Set C
knamely be the two-dimensional optical orthogonal code with zero correlation window that will obtain, in the present embodiment, obtain the two-dimensional optical orthogonal code that 13 have zero correlation window.Certainly, in other cases, basic pulse number (pulse number) m is different with number of wavelengths value, can obtain different two-dimensional optical orthogonal code C
k.
The invention still further relates to a kind of device realizing said method, as shown in Figure 3,4, said apparatus comprises First ray structural unit 1, second sequence structure unit 2 and light orthogonal code forming unit 3 to its structural representation.In these unit, First ray structural unit 1 is for there is the First ray of zero correlation zone, this First ray is the binary sequence formed by 0,1, its Cycle Length equals the code length of code word, the main peak of auto-correlation function equals the number of basic pulse, the submaximum value of auto-correlation function has 1,0 two values; Second sequence structure unit 2 is for constructing the second sequence, and this second sequence is a kind of frequency hop sequences, and its all code word is isometric, and code length equals the pulse number of above-mentioned First ray, and number of wavelengths is greater than the pulse number of First ray; In each code word of the second sequence, each wavelength is to once multiplex; Light orthogonal code forming unit 3 is for mapping First ray and the second sequence, then form the two-dimensional optical orthogonal code with zero correlation window, in this two-dimensional optical orthogonal code, each wavelength is extremely once multiplex in each code word, this two-dimensional optical orthogonal code with zero correlation window is in arbitrary time shifting, and any two different code words have an overlapping wavelengths at the most.Further, above-mentioned second sequence structure unit 2 comprises parameter acquisition module 21 and modular arithmetic module 22; Wherein, parameter acquisition module 21 is for obtaining number of wavelengths and the code length of the second sequence according to First ray; Modular arithmetic module 22 is for according to number of wavelengths and code length, and respectively by several second sequence of wavelength that its mould addition that is number of wavelengths obtains specifying, the code length of this second sequence is the pulse number of First ray.And light orthogonal code forming unit 3 comprises wavelength further obtains module 31 and pulse control module 32; Wherein, wavelength obtains module 31 for obtaining the wavelength value corresponding to the wavelength sequence number represented by each code element content of the second sequence; Pulse control module 32 answers the wavelength value corresponding to the wavelength sequence number represented by the code element content of position for making the basic pulse of each code element of First ray for the second sequence pair.
As shown in Figure 4, in the present embodiment, First ray structural unit 1 comprises setting parameter and initialize module 11, pulse spacing assignment module 12, pulse spacing judge module 13, pulse spacing sequence number judge module 14 and pulse spacing obtain module 15 further; Wherein, setting parameter and the zero correlation section length Z of initialize module 11 for given pulse number m, sequence, spacing (pulse spacing) δ of adjacent two pulses
t, set intermediate variable mal and initialize, wherein, 1≤t≤m, and t is integer; Pulse spacing assignment module 12 for by intermediate variable mal assignment to δ
t; Pulse spacing judge module 13 exists for judging whether
or
in this way, mal value is from adding 1 assignment to δ
tand repeat above-mentioned judgement; Otherwise, by mal value assignment to δ
t; Wherein, exist
in, 1≤i < j < t, 1≤i < m, 1≤j < m, 1≤t≤m, and i, j, t are integer; ?
in, 1≤i < j < r < t, 1≤i < m, 1≤j < m, 1≤r < m, 1≤t≤m, and i, j, r, t are integer; Pulse spacing sequence number judge module 14 is for judging whether t is less than m, and in this way, mal value is from adding 1, t from adding 1; Pulse spacing obtains module 15 and read δ after terminating to judge
1, δ
2..., δ
mvalue and return.
In the present embodiment, basic sequence s(First ray due to by LA) and frequency hop sequences OCS(second sequence) map, namely make the basic sequence s(First ray of LA) basic pulse of each code element is frequency hop sequences OCS(second sequence) wavelength value corresponding to wavelength sequence number represented by correspondence position code element content, thus form a kind of two-dimensional optical orthogonal code with zero correlation window, by analyzing this two-dimensional optical orthogonal code code word and characteristic thereof, in this code word, each wavelength is at most only with once in each code word, so just makes the auto-correlation of this code word be 0; In arbitrary time shifting, any two different code words have at most an overlapping wavelengths, and this is limited to 1 with regard to making the cross-correlation of this code word.In addition, also there is a zero correlation block, the length of zero correlation block equals the zero correlation section length Z of LA basic sequence (First ray).The length Z=16 of the zero correlation block of the two-dimensional optical orthogonal code constructed in the present embodiment.
The cycle Hamming autocorrelation peak of this two-dimensional optical orthogonal code code word is 8, and in the zero correlation block of Z=16, autocorrelation sidelobe is zero.The peak-peak of cross-correlation is 1, and has in the zero correlation block of Z=16, and cross-correlation is 0.By the cross-correlation function figure (not shown) with the two-dimensional quadrature code of zero correlation window that software emulation goes out, in the zero correlation block of Z=16, code word is completely orthogonal.Therefore, as long as the delay between user is in the zero correlation block of Z=16, code word is completely orthogonal, and this will eliminate multi-access inference and the beat noise of two-dimentional OCDMA system completely, also can eliminate the near-far interference of two-dimentional OCDMA system.Therefore, the two-dimensional optical orthogonal code with zero correlation window of the present invention's structure, can realize jumbo OCDMA system, be applied to optical access network, optical local area network, light code labeling switching network, Fibre Optical Sensor net.
The above embodiment only have expressed several execution mode of the present invention, and it describes comparatively concrete and detailed, but therefore can not be interpreted as the restriction to the scope of the claims of the present invention.It should be pointed out that for the person of ordinary skill of the art, without departing from the inventive concept of the premise, can also make some distortion and improvement, these all belong to protection scope of the present invention.Therefore, the protection range of patent of the present invention should be as the criterion with claims.
Claims (9)
1. there is a formation method for the two-dimensional optical orthogonal code of zero correlation window, it is characterized in that, described in there is zero correlation window two-dimensional optical orthogonal code comprise the First ray and the second sequence with zero correlation zone, comprise the steps:
A) there is the First ray of zero correlation zone; Described First ray is the binary sequence formed by 0,1; The Cycle Length of described First ray equals the code length of code word; The main peak of the auto-correlation function of described First ray equals the number of basic pulse; The submaximum value of the auto-correlation function of described First ray has 1,0 two values; There is a zero correlation block in auto-correlation, the basic pulse interval δ t of First ray is not less than zero correlation section length Z;
B) the second sequence is constructed; Described second sequence is a kind of frequency hop sequences, and all code words of described second sequence are isometric; The code length of described second sequence equals the pulse number of described First ray; The number of wavelengths of described second sequence is greater than the pulse number of First ray; In each code word of described second sequence, each wavelength is to once multiplex;
C) described First ray and described second sequence are mapped, then form the two-dimensional optical orthogonal code with zero correlation window; In described two-dimensional optical orthogonal code, each wavelength is extremely once multiplex in each code word; The described two-dimensional optical orthogonal code with zero correlation window is in arbitrary time shifting, and any two different code words have an overlapping wavelengths at the most; The described two-dimensional optical orthogonal code with zero correlation window, in zero correlation window, the auto-correlation of any code word equals zero, and the cross-correlation limit of any two code words equals zero; The described two-dimensional optical orthogonal code with zero correlation window comprises the First ray and the second sequence with zero correlation zone, and described mapping is the pulse with the corresponding element position of the wavelength control First ray corresponding to the wavelength sequence number represented by each code element content of the second sequence.
2. the formation method with the two-dimensional optical orthogonal code of zero correlation window according to claim 1, is characterized in that, the code length N of described First ray, and basic pulse number m, zero correlation section length Z, exist following relation: N >=m (m-1)+2Z-1.
3. the formation method with the two-dimensional optical orthogonal code of zero correlation window according to claim 2, is characterized in that, described steps A) comprise the steps: further
A1) the zero correlation section length Z of given pulse number m, sequence, the spacing δ of adjacent two pulses
t, set intermediate variable mal and initialize; Wherein, 1≤t≤m, and t is integer;
A2) by intermediate variable mal assignment to δ
t, perform steps A 3);
A3) judge whether to exist
in this way, mal value is from adding 1 and returning steps A 2); Otherwise, by mal value assignment to δ
t, perform steps A 4); Wherein, exist
in, 1≤i < j < t, 1≤i < m, 1≤j < m, 1≤t≤m, and i, j, t are integer; ?
in, 1≤i < j < r < t, 1≤i < m, 1≤j < m, 1≤r < m, 1≤t≤m, and i, j, r, t are integer;
A4) judge whether t is less than m, in this way, mal value, from adding 1, t from adding 1, performs steps A 2); Otherwise, perform steps A 5);
A5) δ is read
1, δ
2..., δ
mvalue and return.
4. the formation method with the two-dimensional optical orthogonal code of zero correlation window according to claim 3, is characterized in that, described step B) comprise the steps: further
B1) number of wavelengths and the code length of the second sequence is obtained according to First ray;
B2) according to number of wavelengths and code length, respectively by several second sequence of wavelength that its mould addition that is number of wavelengths obtains specifying, the code length of described second sequence is the pulse number of described First ray.
5. the formation method with the two-dimensional optical orthogonal code of zero correlation window according to claim 4, is characterized in that, described step C) comprise the steps: further
C1) each wavelength value corresponding to wavelength sequence number represented by code element content of the second sequence is obtained;
C2) basic pulse of each code element of First ray is made to answer the wavelength value corresponding to the wavelength sequence number represented by the code element content of position for the second sequence pair.
6. realize a device as claimed in claim 1 with the formation method of the two-dimensional optical orthogonal code of zero correlation window, it is characterized in that, comprising:
First ray structural unit: for there is the First ray of zero correlation zone; Described First ray is the binary sequence formed by 0,1; The Cycle Length of described First ray equals the code length of code word; The main peak of the auto-correlation function of described First ray equals the number of basic pulse; The submaximum value of the auto-correlation function of described First ray has 1,0 two values; There is a zero correlation block in auto-correlation, the basic pulse interval δ t of First ray is not less than zero correlation section length Z;
Second sequence structure unit: for constructing the second sequence; Described second sequence is a kind of frequency hop sequences, and all code words of described second sequence are isometric; The code length of described second sequence equals the pulse number of described First ray; The number of wavelengths of described second sequence is greater than the pulse number of First ray; In each code word of described second sequence, each wavelength is to once multiplex;
Light orthogonal code forming unit: for described First ray and described second sequence being mapped, then form the two-dimensional optical orthogonal code with zero correlation window; In described two-dimensional optical orthogonal code, each wavelength is extremely once multiplex in each code word; The described two-dimensional optical orthogonal code with zero correlation window is in arbitrary time shifting, and any two different code words have an overlapping wavelengths at the most; The described two-dimensional optical orthogonal code with zero correlation window, in zero correlation window, the auto-correlation of any code word equals zero, and the cross-correlation limit of any two code words equals zero; The described two-dimensional optical orthogonal code with zero correlation window comprises the First ray and the second sequence with zero correlation zone, and described mapping is the pulse with the corresponding element position of the wavelength control First ray corresponding to the wavelength sequence number represented by each code element content of the second sequence.
7. device according to claim 6, is characterized in that, described First ray structural unit comprises further:
Setting parameter and initialize module: for the zero correlation section length Z of given pulse number m, sequence, the spacing δ of adjacent two pulses
t, set intermediate variable mal and initialize; Wherein, 1≤t≤m, and t is integer;
Pulse spacing assignment module: for by intermediate variable mal assignment to δ
t;
Pulse spacing judge module: exist for judging whether
or
in this way, mal value is from adding 1 assignment to δ
tand repeat above-mentioned judgement; Otherwise, by mal value assignment to δ
t; Wherein, exist
in, 1≤i < j < t, 1≤i < m, 1≤j < m, 1≤t≤m, and i, j, t are integer; ?
in, 1≤i < j < r < t, 1≤i < m, 1≤j < m, 1≤r < m, 1≤t≤m, and i, j, r, t are integer;
Pulse spacing sequence number judge module: for judging whether t is less than m, in this way, mal value is from adding 1, t from adding 1;
Pulse spacing obtains module: after terminating to judge, read δ
1, δ
2..., δ
mvalue and return.
8. device according to claim 7, is characterized in that, described second sequence structure unit comprises further:
Parameter acquisition module: for obtaining number of wavelengths and the code length of the second sequence according to First ray;
Modular arithmetic module: for according to number of wavelengths and code length, respectively by several second sequence of wavelength that its mould addition that is number of wavelengths obtains specifying, the code length of described second sequence is the pulse number of described First ray.
9. device according to claim 8, is characterized in that, described light orthogonal code forming unit comprises further:
Wavelength obtains module: for obtaining the wavelength value corresponding to the wavelength sequence number represented by each code element content of the second sequence;
Pulse control module: answer the wavelength value corresponding to the wavelength sequence number represented by the code element content of position for the second sequence pair for making the basic pulse of each code element of First ray.
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| CN106877968B (en) * | 2017-01-20 | 2019-06-14 | 深圳大学 | When a kind of/building method and system of frequency domain zero correlation block two dimension bipolar code |
| CN108242966B (en) * | 2017-12-26 | 2019-05-17 | 深圳大学 | The building method of the multiple-length light orthogonal code of orthogonal Latin matrix based on extension |
| CN108234058B (en) * | 2017-12-28 | 2019-05-17 | 深圳大学 | A kind of building method of stringent related constraint light orthogonal code |
| CN109039523B (en) * | 2018-07-31 | 2020-03-20 | 深圳大学 | Construction method and system of large zero correlation zone two-dimensional unipolar code |
| CN111049616B (en) * | 2019-12-24 | 2021-02-19 | 广西师范大学 | Construction method of two-dimensional variable code heavy optical orthogonal code suitable for OCDMA system |
| CN113660054B (en) * | 2021-08-06 | 2022-07-08 | 深圳大学 | Two-dimensional lambda-t optical coding method and code word design |
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