WO2002084914A1

WO2002084914A1 - Implement method of ternary spread spectrum sequence coding in cdma system

Info

Publication number: WO2002084914A1
Application number: PCT/CN2001/000560
Authority: WO
Inventors: Xiaohu Tang; Pingzhi Fan
Original assignee: Linkair Communications, Inc.
Priority date: 2001-04-18
Filing date: 2001-04-18
Publication date: 2002-10-24
Also published as: CN1201514C; CN1429440A

Abstract

This invention publishes an implement method of ternary spread spectrum coding in CDMA system. This spread spectrum code group consists of basic pulse of normalized amplitudes and duration of 1 and polarity; first, giving the number of basic pulses and the length of zero correlation zone (ZCZ) for the LA (large Area) sequence, and generating a basic sequence s that its length is N; then generating a binary orthogonal sequence group, and extending the binary orthogonal sequence to ternary sequence; finally, multiplying the basic sequence s by each of the ternary sequence group as bit, thereby obtaining ternary spread spectrum sequence group A. It is important that basic sequence s is constructed by setting relationship between each of pulse interval δ1 and zero correlation zone to computing pulse interval of the sequence. This spread spectrum coding method apply to anisochronous CDMA communication system, reduce or rather eliminate common channel interference, and increase system's capacity and simplify the design of a CDMA system.

Description

Method for implementing ternary spread spectrum sequence coding in code division multiple access system

The present invention relates to a coding technique for spread spectrum and multiple-access wireless communication, and more particularly to a low-interference or non-interference code division multiple access coding method for spread-spectrum serial code working in a quasi-synchronous manner.

Background of the invention

The function of the wireless communication system is constantly strong, and it can provide multiple voice, data, and image services at the same time, so as to meet users' increasing communication needs. In wireless communications, the use of the frequency spectrum is the most critical. Code division multiple access (CDMA) technology is the most effective way to improve the utilization of the frequency spectrum. Compared with traditional wireless multiple access technologies such as frequency division multiple access (FDMA) and time division multiple access (TDMA), CDMA has soft capacity, anti-multipath and anti-interference capabilities.

The capacity of a CDMA system depends on the interference level of the system. The smaller the interference, the higher the system capacity. In order to further reduce the interference in the CDMA communication system, a synchronous CDMA communication system has been proposed, that is, to strictly maintain synchronization between the base station and each user, such as using global positioning system (GPS) technology Or other complex high-precision synchronization technology and so on. At present, an Synchronous Code Division Multiple Access communication system uses an orthogonal Walsh code or an Adachi code as a spreading sequence code group. For mobile communication systems, accurate uplink synchronization is not easy to guarantee, and multi-path propagation of wireless channels makes system synchronization more difficult. The inter-code correlation characteristics of Walsh or Adachi codes are only zero during synchronization. When the cross-correlation value is not zero when the horses are not synchronized, there is multiple access interference. In addition, due to the near-far effect, synchronous code division multiple access communication will be further reduced. The performance of the system limits the system capacity. In order to minimize the effects of near and far effects, in practical systems such as IS-95, complex fast power control technology is used. However, this will increase the complexity of system implementation, and also increase the overhead of control resources, thereby increasing the system cost.

Therefore, another way to reduce the interference in the CDMA communication system is to reduce the system's requirements for synchronization accuracy. For this reason, in recent years, some people have proposed a quasi-synchronous or near-synchronous CDMA communication system, so that the synchronization error of the system is controlled within a certain range (such as one or several chip periods), and the design of the spreading code is Started research work. At present, there are some related patents, such as: Chinese patent PCT / CN98 / 00151 (CN1175828A) "Using a ternary spreading code group with zero correlation area"; Japanese patent TY99002 (11-023252) Kind of binary spreading sequence code group with zero correlation area "; Japanese patent PCT / JP97 / 03272 (JP271858 / 96)" Using a spreading sequence code group with comb spectrum "and so on. However, the correlation function of the spreading sequences proposed in the two Japanese patents may be very large outside the zero correlation region. If the system synchronization error exceeds the expected range, the interference caused by such spreading sequences will be difficult to control.

Summary of the Invention

From the above analysis, it can be seen that the object of the present invention is to propose a method for implementing ternary spreading sequence coding in a low-interference or non-interference quasi-synchronous CDMA communication system, so as to reduce or even eliminate noise. Other disturbances greatly increase the system capacity, while reducing the system's requirements for power control and synchronization, and achieving a single package, reducing the complexity of system implementation.

Generally, in an ideal case, the spreading sequence set used in a CDMA communication system should have the following related characteristics:

1. The autocorrelation function of each spreading sequence should be an impulse function, that is, in addition to zero delay, Its value should be zero everywhere.

2. The cross-correlation function value of each pair of spreading sequences should be zero everywhere.

Unfortunately, whether it is a binary, multivariate, or complex sequence, it has been proven that a sequence set with such ideal correlation characteristics does not exist. For a given sequence period and number, the maximum autocorrelation function edge peak value and the maximum cross-correlation function value of a sequence set cannot be zero at the same time. They are limited by some theoretical circles. One of them is required to be small, and the other is necessarily increased. Welch, Sidelnikov, etc.

Although it is impossible to design a spreading sequence code group with ideal auto-correlation and cross-correlation characteristics, a zero-correlation area spreading sequence code group with ideal correlation characteristics within the allowable synchronization error range can be designed for a quasi-synchronous CDMA system. In this regard, the Chinese patent PCT / CN98 / 00151 (CN1175828A) provides a good idea, and gives a ternary spreading sequence code group with a zero correlation area-a large area (LA, Large Area) sequence.

The so-called LA sequence is composed of basic pulses with normalized amplitude and width of 1 and polarities. The basic pulses are unequal and different on the time axis. Using such unequal and different pulse positions and pulses The polarity arrangement codes, and the sequence has the following characteristics:

1) the main peak of the autocorrelation function is equal to the number of basic pulses;

2) There are only three cases of sub peaks of the auto-correlation and cross-correlation functions: 1, 0, -1;

3) There is a zero correlation region near the origin of the auto-correlation and cross-correlation functions.

Correlation functions here include periodic correlation, aperiodic correlation, and periodic odd correlation.

It can be known from the above that the correlation function of the LA sequence is very low outside the zero correlation region, which is 0, 1, or -1. Even if the system synchronization error exceeds the expected range, there will only be low interference. More importantly, in addition to the zero correlation area of the periodic correlation function, the LA sequence also has the zero correlation area of the non-periodic correlation function not available in other sequences. According to the system performance analysis results, the system performance is determined by the periodic and non-periodic The period correlation function values are jointly determined. Taking the Large Area Synchronous Code Division Addressing (LAS-CDMA) system as an example, the use of LA sequence sets in its system can greatly suppress or even eliminate multiple-access interference (MAI) and inter-symbol interference (ISI). Adjacent cell interference (ACI) is also minimized. Therefore, it can make the LAS-CDMA system have higher spectral efficiency, higher transmission data rate, and faster moving speed. Theoretically, it can be more than 3 times the capacity of CDMA2000. It can provide up to 5.53Mb / s data transmission at 1.25MHz bandwidth. Rate, can adapt to the development requirements of packet switching and all-IP networks.

However, compared with the sequence length, the LA sequence set has a significantly smaller number of sequences, that is, it can support fewer users under the same sequence length, and the spectrum utilization rate is low. Because the sequence set has the same sequence length, if there are more sequences, it means that more users can be supported, and the spectrum utilization rate is higher. The present invention is directed to this fact, and on the premise of maintaining the excellent correlation characteristics of the LA sequence, the length of the LA sequence is greatly shortened, that is, the utilization rate of the frequency spectrum is improved. In addition, in the original patent, the basic pulse interval of the LA sequence can only have any odd number greater than the minimum interval (that is, the zero correlation area), and the rest are even numbers. In this way, excessively restricting the pulse interval will cause an existing LA sequence. Longer makes the performance of the sequence worse. The present invention removes this requirement and constructs a shorter LA sequence.

Given that the basic pulse number m of the LA sequence is even and the length of the zero correlation region is Z _ez , a sequence s of length N is first generated, which is called the base sequence of the LA sequence. Assume that the distribution positions of the basic pulses in the base sequence s are x _P x ₂ and x _m , respectively, and let the intervals of adjacent basic pulses be δ δ ₂ , 5 _m . That is: 5 _; = x _{i + 1} -x _;, i = 1, 2, .. ,, ml. Set S _m = Nx _{m again} , these pulse intervals should meet:

1, 5;> Z _cz , l <i <m;

2. l <i≤j <s≤t <m;-

3. ∑ ^ A- ≠ ∑¾ 'tn <i <j <s≤m <t≤2m-2; where S _{k =} S _k . _M , when k> m. That is, all pulse intervals (including S _m ) are greater than or equal to Z _cz , and the difference between the positions of any two basic pulses is different under the modulo N operation. Then the autocorrelation of the base sequence s satisfies the characteristics of the LA sequence 1), 2), 3).

Second, generate a set of binary orthogonal sequences {b ¹ , b ² , .. ·, b ^m } of length ^m , where

, b [,…, 2, ···, M, satisfy

R _b , _tbi (0) -0, i ≠ j

when! !! !! Three ^11, Walsh sequence group may be employed as the orthogonal sequence group. Then, the orthogonal sequence group is extended as follows to generate a ternary sequence {c ¹ , c ² ,..., C ^m } l, 2, ..., M, k = 0,2, ~ , Nl

Finally, the base sequence s is multiplied bitwise with each sequence in the ternary sequence group {c ¹ , c ² , c ^ra } to obtain the ternary sequence group ^ 4

…, S _N. , C}, is the so-called LA sequence.

The inter-sequence correlation of a sequence set is completely determined by the autocorrelation characteristics of the base sequence s. Considering the periodic correlation function of aa ^j , l <i, j <M, according to the condition 1, which is satisfied by the pulse interval, the time delay τ <Z. _{At ζ} , the non-zero elements in them will not meet, so there is a zero correlation zone Z _ez ; according to conditions 2 and 3, for a fixed delay τ, the non-zero elements in them meet at most once, so the sub-peak is only 1, 0,-1 three cases. The non-periodic correlation characteristics are similar to the periodic odd correlation characteristics, and the sub-peaks have only three cases: 1, 0, and -1. Therefore, it is a set of LA sequences. The zero correlation areas of the periodic correlation, non-periodic correlation, and periodic odd correlation functions are all equal to Z _cz .

The base sequence s-sequence is the basis of the LA sequence, and the pulse distribution position _Xp x _{2 in the} s-sequence, x _m, or a pulse interval _{_{δ Ρ δ 2,, 3 "}} 1 3 is the core sequence that is:.... For the basic sequence S, s pulse interval is determined, thereby also determining the position pulse distribution. Given the number of basic pulses of the LA sequence and the length of the zero correlation region, it is most critical to construct an s-sequence with the smallest or smallest possible length.

In view of this, the main purpose of the present invention is to construct an s-sequence with the smallest or as short a length as possible, so that the system can greatly increase the system capacity while reducing interference and reducing implementation complexity; and, reducing the system's power control And synchronization requirements.

To achieve the above object, the technical solution of the present invention is implemented as follows:

A method for implementing ternary spreading sequence coding in a code division multiple access system. The spreading sequence code group is composed of basic pulses with a normalized amplitude and width of 1 and polarity, and includes at least the following steps. :

a. Given the number of basic pulses of the LA sequence and the length of the zero correlation region, generate a base sequence s of length N;

b. Generate a binary orthogonal sequence group of length m, the orthogonal sequence group may be a Walsh sequence group, and then expand the binary orthogonal sequence group into a ternary sequence of length N;

c multiply the base sequence s and each sequence of the ternary sequence group by bit to obtain the ternary spreading sequence code group A;

It is important that the method of generating the base sequence s further includes the following steps:

d. Set the relationship between each pulse interval ^ and the length of the zero correlation zone Z _cz , and calculate the pulse interval of the base sequence s.

All the basic pulse intervals of the spreading sequence code group are greater than or equal to the length of the zero correlation region Z _cz , and the difference between the positions of any two basic pulses is different under the operation of the modulus sequence length. The pulse interval is odd or even. The autocorrelation function of any sequence in the spreading sequence code group has a zero correlation area on both sides of the zero shift and the zero shift. There are zero correlation areas on both sides of the zero shift. Outside the zero correlation area, the auto-correlation value and cross-correlation value are only 1, 0, and -1. The correlation functions include periodic correlation, aperiodic correlation, and periodic odd correlation, and the zero correlation regions of the three correlation functions are all equal.

According to the above scheme and the three conditions to be satisfied by the pulse interval, the construction method 1 can be directly obtained. The method includes at least the following steps:

Step 1. Let S Zcz, = Z _CZ +1, 5 ₃ = Z _cz + 2, n = 3;

Step 2.? T- Vl <i <j <s <t <n, whether it exists

1 ^{= + δ} or tm <i <j <s <n <t <2m-2; if it exists, then 5 = 5 + 1, continue to step 2;

Step 3.If n = m-l, determine whether it exists

∑ ^ ≠ ∑ ^ 't-m <i <j <s <n <t <2m-2;, if it exists, then 5 = 5 + 1' Go to step 2;

Step 4. Let n = n + 1, 5 _m = 5, and δ = δ + 1. If n = m, δ δ ₂ , 5 _m is required, otherwise go to step 2.

However, the pulse interval in the construction method 1 is strictly increasing. Generally, the sequence of the pulse intervals in increasing order cannot reach the minimum length. To this end, the method 1 can be used as a basis to further improve the algorithm, so another method is proposed. Program:

A method for implementing ternary spreading sequence coding in a code division multiple access system. The spreading sequence code group is composed of basic pulses with a normalized amplitude and width of 1 and polarity, and includes at least the following steps. : a. Given the basic pulse number of the LA sequence and the length of the zero correlation region, generate a base sequence s of length N;

c multiplies the base sequence s and each sequence of the ternary sequence group bit by bit to obtain a ternary spreading sequence code group A;

d. Set each pulse interval 5; the relationship with the length Z _{C of the} zero correlation zone, and calculate the pulse interval of the base sequence s;

e. According to the pulse interval calculated in step b, generating one or more parent sequences with a length of zero correlation region greater than or equal to Z _ez and less than or equal to Z _ez + N-1;

f. Calculate the length of each parent sequence;

g. Randomly select two parent sequences, truncate the sequence at a randomly selected position, and exchange the corresponding parts of the two sequences to generate two subsequences; repeat step f until a certain number of subsequences are generated;

h. Calculate the length of each subsequence;

i. Select one or more child sequences with the shortest length as the new parent sequence;

j. After running the specified time, choose the shortest sequence as the solution.

A certain number of subsequences in step g and the specified time in step j are determined by the empirical values of the length of the zero correlation area and the number of pulses.

Step g further includes the following steps: When the pulse interval of the exchanged part and the non-exchanged part of the two new subsequences conflicts, only the non-conflicted pulse interval of the non-exchanged part is retained, and then the step from the next bit of the conflicting pulse interval is followed. b Calculate the pulse interval to regenerate a new subsequence Column. Among them, the pulse interval conflict means that the same pulse interval occurs in the exchanged part and the non-exchanged part. All the basic pulse intervals of the spreading sequence code group are greater than or equal to the length of the zero correlation region Z _cz , and the difference between the positions of any two basic pulses is different under the operation of the modulus sequence length. The pulse interval is odd or even.

The autocorrelation function of any sequence in the above-mentioned spreading sequence code group has a zero correlation area on both sides of zero shift and zero shift. The cross-correlation function of any pair of sequences in the spreading sequence code group is at zero shift and zero. There are zero correlation areas on both sides of the shift. Outside the zero correlation area, the auto-correlation value and cross-correlation value are only 1, 0, and -1. The correlation functions include periodic correlation, aperiodic correlation, and periodic odd correlation, and the zero correlation regions of the three correlation functions are all equal.

• The second construction method includes the following steps:

Step 1. Use method one to generate n parent sequences whose length of the zero correlation region is greater than or equal to Z _ez and less than or equal to Z _ez + nl;

Step 2. Calculate the length of each parent sequence;

― Step 3. Cross. That is, two parent sequences are randomly selected, they are truncated at a randomly selected position, and their corresponding parts are exchanged to generate two child sequences. Note that these two sequences are likely to conflict with the previous part (that is, the conditions 2 and 3 of the pulse interval are not met), then only all the non-conflicting δs are retained. Use method one to generate a new subsequence. Repeat this operation until a certain number of subsequences are generated;

Step 4. Calculate the length of each subsequence;

Step 5. Compete. Select the n shortest sequence as the new parent sequence;

Step 6. After running for a specified time, select the shortest sequence as the solution.

Among them, the "a certain number" of "until a certain number of subsequences" in step 3; the "n" of "the shortest n subsequences" in step 5; the "regulation of" run a specified time "in step 6 These three values are obtained from empirical values, which are related to the length of the zero correlation area and the number of pulses. Generally, the more the number of pulses, the larger these values. In theory, the larger these values The more likely the length of the obtained LA sequence is the smallest, that is, the better the performance. Taking the LA sequences in Tables 2 and 3 as an example, the number of parent sequences n in Tables 2 and 3 is 15, 30, and a subsequence is generated each time. 40, 80, the running time is specified as 10 minutes.

According to the second method, a shorter LA sequence than that of the first method can be obtained, as shown in Tables 2 and 3.

Brief description of the drawings

FIG. 1 is an example of an LA sequence code group according to the present invention (take 8 basic pulses and a zero correlation area length of 16 as an example);

FIG. 2 is a periodic autocorrelation function diagram of the present invention (taking sequence 1 in FIG. 1 as an example);

FIG. 3 is a periodic autocorrelation function diagram of the present invention (taking sequence 2 in FIG. 1 as an example);

FIG. 4 is a periodic cross-correlation function diagram of the present invention (taking sequence 1 and sequence 2 in FIG. 1 as an example); FIG. 5 is a non-periodic autocorrelation function diagram of the present invention (taking sequence 1 in FIG. 1 as an example); FIG. 6 Is a non-periodic autocorrelation function diagram of the present invention (taking sequence 2 in FIG. 1 as an example); FIG. 7 is a non-periodic cross-correlation function diagram of the present invention (taking sequence 1 and sequence 2 in FIG. 1 as an example); FIG. 8 is The periodic odd correlation autocorrelation function diagram of the present invention (taking sequence 1 in FIG. 1 as an example); FIG. 9 is the periodic odd correlation autocorrelation function diagram of the present invention (taking sequence 2 in FIG. 1 as an example); FIG. 10 is the present invention The graph of the periodic odd correlation autocorrelation function (take sequence 1 and sequence 2 in Figure 1 as an example). Mode of Carrying Out the Invention The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

Tables 1, 2, and 3 show the basic pulse intervals corresponding to the base sequence s, that is, the values of δ i-1, 2,,..., And m. They are arranged in the basic pulse interval column in the order of δ _,, δ ₂ ,..., Δ _η ^. Given the number of basic pulses m and the length of the zero correlation zone Z _ez , the pulse interval of the base sequence s can be obtained by looking up tables 1, 2 or 3, thereby determining the sequence s.

After a given number of pulses substantially m, as long as the length of zero correlation zone Z _ez ≥m ^2/4, when m = 4, 8, 16, 32, 64 can be obtained theoretically minimum length base sequence s, which corresponds substantially The pulse interval is shown in Table 1. When the length of a zero correlation zone Z _ez <m ^2/4, the use of two construction method, Tables 2 and 3 list the pulse interval of 16 basic pulses and 32 basic pulses small length s corresponding to the base sequence, wherein Table 2 sequence almost reached the minimum length, when the sequence in table 3 is greater than equal to ₂ 160, it is also at or very close to the minimum length.

Table 1: Z _cz basic pulse interval ≥m ^2/4

The basic pulse number Zcz≥m ^2/4

(M) m ^2/4 basic pulse interval

4 4 {Z _cz , Z _cz + l, Z _cz +3, Z _cz +2}

8 16 {Zcz, Zcz + l, Z _cz + 2, Z _cz + 4, Z _cz + 3, Z _cz + 6, Z _cz + 7, Z _cz +5}

16 64 (Zcz, Zcz + Z _cz + 2, Zc _Z +3 ₎ Zcz + 4, Zcz + 5, Zcz + 6 _; Zcz + 7, Z _cz + 8, Zcz + 9, Zcz +

10, Zcz + 14, Z _cz + 13, Z _CZ + 15, Z _C2 +11, Z _CZ +12}

32 256 {Z _CZ , Z _CZ +1, Z _CZ + 2, Z _CZ + 3, Z _CZ + 4, Z _CZ + 5, Z _CZ + 6, Z _CZ + 7, Z _CZ +8, Z _CZ +9 , Z _CZ +

10, Zcz + H, Z _CZ + 12 ₎ Zcz + 13 ₎ Z _cz + 14, Z _C z + 15, Z _CZ +16, Z _CZ + 17, Z _CZ + 18, Z _CZ +] 9, Z _C z + 20,2cz + 21, Z _CZ + 23, Z _CZ + 27, Z _CZ + 22, Z _CZ + 25, Z _CZ + 26, Z _CZ + 30, Z _C _z + 24, Zcz + 29, Z _cz +31 , Z _cz +28}

(Zcz, Zc _Z + l, Zcz + 2 _J Zcz + 3, Zcz + 4 ₎ Zc2 + 5 ₎ Zcz + 6, Zcz + 7, Z _cz +8 _J Zcz + 9, Zcz +

64 1024 10, Z _CZ + 1 1, Z _CZ + 12, Z _CZ + 13, Z _CZ + 14, Z _CZ + 15, Z _CZ + 16, Z _CZ + 17, Z _CZ + 18, Z _CZ

+ 19, Zcz + 20 ₎ Zcz + 21, Zc _Z +22 ₎ Zcz + 23, Zcz + 24 ₁ Zc2 + 25, Zcz + 26, Z _cz +27 ₎ Zc z + 28 ₎ Zcz + 29, Zc _Z +30 _; Zc _Z +31, Zcz + 32, Zcz + 33 ₎ Z _cz + 34, Z _C 2 + 35, Zcz + 36, Z cz + 37, Zcz + 38, Zcz + 39, Zcz + 40, Z _cz +41 , Zcz + 42, Zc2 + 43, Zcz + 44, Zc2 + 45,

Z _cz + 46, Z _cz + 48, Z _cz + 49, Z _cz + 50, Z _cz + 52, Z _cz + 56, Z _cz + 47, Z _cz + 53, Z _cz +54

, Z _cz + 60, Z _cz +51, Zcz + 55, Zcz + 62 ₎ Z _cz + 59, Zcz + 57 ₎ Zcz + 63, Zcz + 61} Table 2: 16 basic pulse intervals

32 basic pulse intervals

Length Basic Pulse Interval

2473 44 45 46 47 48 32 33 34 37 35 38 36 41 40 42 52 49 56 51 97 43 55 63 126 75 142 176 58 79 66 122 565

2562 47 48 49 50 51 52 53 54 55 34 35 37 36 38 40 41 44 42 80 59 45 65 61 57 39 173 70 58 91 264 60 634

2588 62 63 64 65 66 67 38 39 40 41 42 43 47 44 48 46 49 50 58 52 59 45 71 51 68 97 56 188 73 57 172 627

2594 52 53 54 55 56 57 40 41 42 43 44 45 46 48 50 62 59 61 49 47 68 80 69 122 51 65 147 119 58 70 93 648

2644 70 71 72 73 74 75 42 43 44 45 46 47 49 48 53 50 54 51 57 107 62 63 55 59 69 65 1 11 159 167 95 168 400

2663 72 73 44 45 46 47 48 49 50 51 52 54 53 56 55 58 62 57 66 68 61 63 59 74 105 104 77 78 203 131 158 444

2713 78 46 47 48 49 50 51 52 53 54 55 56 57 59 58 60 61 64 63 66 68 67 72 65 75 77 69 89 100 136 148 620

2794 56 57 58 59 60 61 62 63 64 48 49 50 51 53 52 76 67 65 68 54 70 78 71 87 55 75 92 120 96 179 84 614

2864 65 66 67 68 69 52 53 54 55 57 56 58 59 60 62 63 75 64 70 72 73 71 76 74 84 96 61 80 111 86 179 628

2962 70 71 72 73 74 75 54 55 56 58 57 59 61 60 62 63 64 67 65 68 66 78 77 79 83 90 80 99 128 110 87 701

3018 77 78 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 74 71 76 75 84 72 81 94 90 138 85 91 142 106 639

3072 71 72 73 74 75 76 77 78 58 59 60 61 62 66 63 69 64 67 68 70 80 87 98 65 91 102 100 81 101 106 88 710

3131 83 84 85 86 87 60 61 62 63 64 65 67 66 68 71 72 69 75 73 78 76 90 95 79 109 94 70 105 101 98 102 673

3140 78 79 80 81 82 83 84 85 62 63 64 65 67 66 69 6S 72 71 73 75 70 102 91 88 76 74 106 98 96 130 114 628

3229 94 95 96 64 65 66 67 68 69 70 71 72 73 74 75 77 76 79 78 85 80 88 81 98 84 83 97 100 99 82 176 647

3303 74 75 76 77 78 79 80 81 69 66 67 70 68 71 72 84 86 85 82 90 87 73 91 83 92 89 93 104 122 99 147 693

3403 80 81 82 83 84 85 86 87 88 70 68 69 71 72 73 74 75 76 77 79 78 90 89 107 92 98 129 1 10 94 111 103 742 ε!

S00 / T0N3 / X3d 6t80 / Z0 OAV

S00 / T0N3 / X3d Μ6 ^ 80 / Z0 OAV 210 7220 219 210 211 212 213 214 216 215 217 218 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 236 237 238 240 239 245

212 7281 234 235 236 237 238 239 240 212 213 214 215 216 217 218 219 220 221

222 223 224 225 226 227 228 229 230 231 232 233 241 242 244

214 7349 222 223 224 225 226 227 228 229 230 231 232 233 234 216 214 217 215

218 219 220 221 235 236 237 238 239 242 240 243 241 244 250

216 7413 224 225 226 227 228 229 230 231 232 233 234 235 236 218 216 219 217

220 221 222 223 237 238 239 240 241 244 242 245 243 246 252

218 7473 240 241 242 243 244 245 246 218 219 220 221 222 223 224 225 226 227

228 229 230 231 232 233 234 235 236 237 238 239 247 248 250

220 7536 243 244 245 246 247 220 221 222 223 224 225 226 227 228 230 229 231

233 232 234 236 238 237 239 240 241 242 248 249 250 251 235

222 7601 244 245 246 247 248 249 250 222 223 224 225 226 227 228 229 229 230 231

232 233 234 235 236 237 238 239 240 241 242 243 251 252 254

224 7664 247 248 249 250 251 224 225 226 227 228 229 230 231 232 234 233 235

237 236 238 240 242 241 243 244 245 246 252 253 254 255 239

226 7728 249 250 251 252 253 226 227 228 229 230 231 232 233 234 236 235 237

239 238 240 242 244 243 245 246 247 248 254 255 256 257 241

228 7792 251 252 253 254 255 228 229 230 231 232 233 234 235 236 238 237 239

241 240 242 244 246 245 247 248 249 250 256 257 258 259 243

230 7857 252 253 254 255 256 257 258 230 231 232 233 234 235 236 237 238 239

240 241 242 243 244 245 246 247 248 249 250 251 259 260 262

232 7920 255 256 257 258 259 232 233 234 235 236 237 238 239 240 242 241 243

245 244 246 248 250 249 251 252 253 254 260 261 262 263 247

234 7984 257 258 259 260 261 234 235 236 237 238 239 240 241 242 244 243 245

247 246 248 250 252 251 253 254 255 256 262 263 264 265 249

236 8049 258 259 260 261 262 263 264 236 237 238 239 240 241 242 243 244 245

246 247 248 249 250 251 252 253 254 255 256 257 265 266 268

238 81 12 261 262 263 264 265 238 239 240 241 242 243 244 245 246 248 247 249

251 250 252 254 256 255 257 258 259 260 266 267 268 269 253

240 8176 263 264 265 266 267 240 241 242 243 244 245 246 247 248 250 249 251

253 252 254 256 258 257 259 260 261 262 268 269 270 271 255

242 8240 265 266 267 268 269 242 243 244 245 246 247 248 249 250 252 251 253

255 254 256 258 260 259 261 262 263 264 270 271 272 273 257

244 8304 267 268 269 270 271 244 245 246 247 248 249 250 251 252 254 253 255

257 256 258 260 262 261 263 264 265 266 272 273 274 275 259

246 8368 269 270 271 272 273 246 247 248 249 250 251 252 253 254 256 255 257

259 258 260 262 264 263 265 266 267 268 274 275 276 277 261

248 8432 271 272 273 274 275 248 249 250 251 252 253 254 255 256 258 257 259

261 260 262 264 266 265 267 268 269 270 276 277 278 279 263

250 8496 273 274 275 276 277 250 251 252 253 254 255 256 257 258 260 259 261

263 262 264 266 268 267 269 270 271 272 278 279 280 281 265

252 8560 275 276 277 278 279 252 253 254 255 256 257 258 259 260 262 261 263

265 264 266 268 270 269 271 272 273 274 280 281 282 283 267

254 8624 277 278 279 280 281 254 255 256 257 258 259 260 261 262 264 263 265

267 266 268 270 272 271 273 274 275 276 282 283 284 285 269

256 8688 279 280 281 282 283 256 257 258 259 260 261 262 263 264 266 265 267

269 268 270 272 274 273 275 276 277 278 284 285 286 287 271 Take the basic pulse interval in Table 1 as an example to explain how to use the given basic pulse interval to construct the corresponding LA sequence. Assume that given the number of basic pulses m = 8 and the zero correlation area Z _ez = 16, the corresponding basic pulse interval {Si, i = l, —, 8} = {16, 17, 18, 20, 19 , 22, 23,

21}, then the base sequence is:

5 = {1,0, ..., 0,1,0, .. ·, 0,1,0,. ·., 0,1,0, ..., 0,1,0, ... , 0,1,0, ..., 0,1,0,. ·., 0,1,0, ..., 0} where "..." represents element 0.

After obtaining the m basic pulse intervals or distribution positions of the base sequence s, the basic pulse polarity is arranged according to an orthogonal sequence code group of length m to generate a spreading sequence code group. Here, the Walsh sequence group W is selected as the orthogonal sequence group:

{1 '1, 1, 1, 1, 1, 1, 1}

W ² =, -1, 1, -1, 1, -1, 1,-] L}

w ³ = {1, 1, -1, -1, 1, 1,--1,-] 1}

w ⁴ = {1, -1, -1 1, 1, -1, -1, "1}

w ⁵ = {1 '1, 1, 1, -1, -1,--1,-' 1}

w ⁶ = {1, -1, 1, -1, -1, 1, -1, "1}

w ⁷ = {1, 1, -1, -1, -1, -1, 1, 1}

w ^8- {1 '-1, -1, 1, -1, 1, 1,-1}

Polar group via a sequence group W s basic pulse sequence rearranged, there is obtained a set of eight sequences i.e., LA: SEQ 1- a ^1, the sequence 2- a ^2, the sequence 3-- a ^3, sequences 4- a ^4, sequence 5- a ^5, sequences 6- a ^6, sequences 7- a ^7, the sequence 8- a ^8. Its zero correlation zone Z _cz = 16, as shown in Figure 1.

Referring to FIG. 2 and FIG. 3, they are the graphs of the periodic autocorrelation functions of sequence 1 and sequence 2 in FIG. 1, respectively. The other sequences have completely similar periodic autocorrelation functions. When the instantaneous delay falls within (-16, 16), the value of the periodic autocorrelation function is zero. Otherwise, there are only three types of periodic autocorrelation values: 1, 0, -1. Situation.

Referring to FIG. 4, it is a cycle-period cross-correlation function diagram of sequence 1 and sequence 2 in FIG. Other arbitrary sequence pairs have completely similar periodic cross-correlation functions. When the instantaneous delay falls within (-16, 16), the value of the periodic cross-correlation function is zero. Otherwise, the periodic cross-correlation value is only 1, 0, -1. Three scenarios.

Referring to Fig. 5 and Fig. 6, they are aperiodic autocorrelation function diagrams of sequence 1 and sequence 2 in Fig. 1, respectively. Other sequences have completely similar non-periodic autocorrelation functions. When the instantaneous delay falls within (-16, 16), the value of the non-periodic autocorrelation function is zero. In addition, the non-periodic autocorrelation value is only 1, 0, -1. Situation.

Referring to FIG. 7, it is a graph of the aperiodic cross-correlation function of sequence 1 and sequence 2 in FIG. 1. Any other sequence pair has a completely similar aperiodic cross-correlation function. When the instantaneous delay falls within (-16, 16), the value of the periodic cross-correlation function is zero. Otherwise, the aperiodic cross-correlation value is only 1, 0, -1 Three situations.

Referring to Figs. 8 and 9, they are periodic odd autocorrelation functions of sequences 1 and 2 in Fig. 1, respectively. Other sequences have completely similar periodic odd autocorrelation functions. When the time delay falls on (-16, 16), the periodic odd autocorrelation function value is zero. Otherwise, the periodic odd autocorrelation value is only 1, 0,- 1 three situations.

Referring to FIG. 10, it is a graph of periodic odd cross-correlation functions of sequence 1 and sequence 2 in FIG. Any other sequence pair has a completely similar periodic odd cross-correlation function. When the instantaneous delay falls within (-16, 16), the value of the periodic odd cross-correlation function is zero. Otherwise, the periodic odd cross-correlation value is only 1, 0. , -1 Three situations.

The above description is only the preferred embodiments of the present invention, and is not intended to limit the protection scope of the present invention.

Claims

Claim

1. An implementation method of ternary spreading sequence coding in a code division multiple access system. The spreading sequence code group is composed of basic pulses with normalized amplitude and width of 1 and polarities, and includes at least the following: Steps:

b. Generate a binary orthogonal sequence group of length m, and then expand the binary orthogonal sequence group to a ternary sequence of length N;

It is characterized in that the method for generating the base sequence s further includes the following steps:

d. Set the relationship between each pulse interval and the length of the zero correlation zone Z _C J, and calculate the pulse interval of the base sequence s;

e. Generate the pulse interval calculated according to step b to generate one or more parent sequences with a length of zero correlation region greater than or equal to Z _ez and less than or equal to Z _ez + N-1;

f. Calculate the length of each parent sequence;

h. Calculate the length of each subsequence;

j. After running the specified time, select the shortest sequence as the solution.

2. The coding method according to claim 1, characterized in that: the spreading sequence code group All the basic pulse intervals are equal to or greater than the zero correlation zone length Z _ez , and the difference between the positions of any two basic pulses is different under the calculation of the length of the modulo sequence.

3. The encoding method according to claim 1 or 2, characterized in that: the pulse interval is an odd number or an even number.

4. The encoding method according to claim 1, characterized in that: the autocorrelation function of any sequence in the spreading sequence code group has a zero correlation area on both sides of zero shift and zero shift, and the spreading sequence The cross-correlation function of any pair of sequences in the code group has a zero correlation area on both sides of the zero shift and zero shift, and the auto-correlation value and cross-correlation value outside the zero correlation area are only 1, 0 and -1.

5. The encoding method according to claim 4, wherein: said correlation functions include periodic correlation, aperiodic correlation and periodic odd correlation, and the zero correlation regions of the three correlation functions are all equal.

6. The encoding method according to claim 1, characterized in that: a certain number of subsequences in step g are determined by the empirical values of the length of the zero correlation region and the number of pulses.

7. The encoding method according to claim 1, characterized in that step g further comprises the following steps: when the pulse interval between the exchanged part and the unexchanged part of the two new subsequences conflicts, only the unexchanged part is retained without conflict And then starting from the next bit of the conflicting pulse interval to regenerate a new subsequence according to the pulse interval calculated in step b.

8. The encoding method according to claim 7, wherein: the pulse interval conflict means that the same pulse interval occurs between the exchanged part and the non-exchanged part.

9. The encoding method according to claim 1, wherein: the specified time in step j is determined by an empirical value of the length of the zero correlation region and the number of pulses.

10. The encoding method according to claim 1, wherein: the orthogonal sequence group in step b is a Walsh sequence group.

11. A method for implementing ternary spreading sequence coding in a code division multiple access system. The spreading sequence code group is composed of basic pulses with normalized amplitude and width of 1 and polarities, and includes at least the following: A step of:

d. Set each pulse interval δ _{; the} relationship with the length Z _{C of the} zero correlation region, and calculate the pulse interval of the base sequence s.

12. The encoding method according to claim 1, characterized in that: all basic pulse intervals of the spreading sequence code group are greater than or equal to zero correlation zone length Z _ez , and the difference between the positions of any two basic pulses is in the mode sequence Different in length calculation.

13. The encoding method according to claim 11 or 12, wherein the pulse interval is an odd number or an even number.

14. The encoding method according to claim 11, wherein: the autocorrelation function of any sequence in the spreading sequence code group has a zero correlation area on both sides of zero shift and zero shift, and the spreading sequence The cross-correlation function of any pair of sequences in the code group has a zero correlation area on both sides of the zero shift and zero shift, and the auto-correlation value and cross-correlation value outside the zero correlation area are only 1, 0 and -1.

15. The encoding method according to claim 14, wherein the correlation function comprises periodic correlation, aperiodic correlation, and periodic odd correlation, and zero correlation regions of the three correlation functions Are all equal.

16. The encoding method according to claim 11, wherein: the orthogonal sequence group in step b is a Walsh sequence group.